## NAGAHIRO HidekoFaculty Division of Natural Sciences Research Group of Physics Associate Professor |

Last Updated :2021/06/02

- hadron physics(theory), mesic nuclei

- Feb. 2017, Osaka University, Research Center for Nuclear Physics Theoretical Nuclear Physics, 特任准教授
- Apr. 2012, Nara Women's University, Department of Physics, Associate Professor
- Oct. 2008 Mar. - 2012, Nara Women's University, 助教
- Apr. 2006 Oct. - 2008, 大阪大学核物理研究センター 学振特別研究員
- Apr. 2005 Mar. - 2006, 大阪大学核物理研究センター 特任研究員

- Apr. 1998, Mar. - 2001, Nara Women's University, Graduate School, Doctral Research Course in Human Culture, 複合領域科学

Non-mesonic decay of the $η$-mesic $^3He$ via $pd→(^3He$-$η)_bound→$ $^3He 2γ (6γ$) reaction

Aug. 2019, Nuclear Physics A, 993, 121647Scientific journal

Formation of Possible \(\eta '\)(958)-Nucleus Bound States and \(\eta '\)N Interaction

Journal of the Physical Society of Japan, 16 Feb. 2017, Proceedings of the 14th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon (MENU2016), doi;urlInternational conference proceedings

$η$-nucleus interaction from the $d+d$ reaction around the $η$ production threshold

The eta mesic nucleus is considered to be one of the interesting exotic many-body systems and has been studied since the 1980s theoretically and experimentally. Recently, the formation of the eta mesic nucleus in the fusion reactions of the light nuclei such as d + d -> (eta + alpha) -> X has been proposed and the experiments have been performed by WASA-at-COSY. We develop a theoretical model to evaluate the formation rate of the eta mesic nucleus in the fusion reactions and show the calculated results. We find that the eta bound states could be observed in the reactions in cases with the strong attractive and small absorptive eta-nucleus interactions. We compare our results with existing data of the d+ d -> eta + alpha and the d+ d -> He-3 + N + pi reactions. We find that the analyses by our theoretical model with the existing data can provide new information on the eta-nucleus interaction., SPRINGER, 2017, Eur. Phys. J. A, 53 (10), 194 - 194, doi;web_of_scienceScientific journal

Decays of doubly charmed meson molecules

If the X(3872), Y(3940) and X(4160) are D*(D) over bar + c.c., D*(D) over bar (S) and D-S*(D) over bar (S)* molecules, respectively, there should be doubly charmed mesons (D-(*D-)(()*())). In this talk we predict two states with J(P) = 1(+) in the charm = 2 sector, one DD* state around 3850 MeV, other D*D* state with mass around 3970 MeV, and other two similar states in the (charm = 2; strangeness = 1) sector. Besides that, we evaluate the decay widths of doubly charm mesons D*D*(1(+)), into DD pi and DD gamma. These decays are mediated by anomalous couplings D*D* - DD*, with the subsequent decay of D* into D pi or D gamma., AMER INST PHYSICS, 2016, AIP Conf. Proc., 1701 (1), 050011 - 050011, doi;web_of_scienceScientific journal

Precision spectroscopy of pionic atoms and chiral symmetry in nuclei

We conduct an experimental project to make spectroscopy of deeply bound pionic atoms systematically over wide range of nuclei. We aim at studying the strong interaction in the low energy region, which has close connection to spontaneous chiral symmetry breaking and its partial restoration in nuclear matter. First experimental results show improved spectral resolution and much better statistical sensitivity than previous experiments. Present status of the experiment is reported., EDP Sciences, 2016, EPJ Web Conf., 130, 01017 - 01017, doi;web_of_scienceScientific journal

Search for \ensuremathη' mesic nuclei by missing-mass spectroscopy of the $^12$C(p,d) reaction

We performed a missing-mass spectroscopy experiment of the 12C(p, d) reaction at 2.5 GeV proton energy in order to search for η′ mesic nuclei. An excitation-energy spectrum of 11C was obtained around the η′ production threshold. As no significant peak structure was observed in the spectrum, upper limits of the formation cross section of η′ mesic nuclei have been determined. Preliminary results of the experiment as well as future prospects are given., EDP Sciences, 2016, EPJ Web Conf., 130, 02010 - 02010, doi;url;urlScientific journal

Decays of doubly charmed meson molecules

The interaction between pseudoscalar and/or vector mesons can be studied using hidden gauge Lagrangians. In this framework, the interaction between charmed mesons has been studied. Furthermore, doubly charmed states are also predicted. These new states are near the D* D* and D* D-s* thresholds, and have spin-parity J(P) = 1(+). We evaluate the decay widths of these states, named as R-cc(3970) and S-cc(4100) (with strangeness), and obtain 44 MeV for the non-strangeness, and 24 MeV for the doubly charm-strange state. Essentially, the decay modes are DD(s)pi and DD(s)gamma, being the D pi and D gamma emitted by one of the D* meson which forms the molecule., WORLD SCIENTIFIC PUBL CO PTE LTD, 2015, Chiral Symmetry in Hadrons and Nuclei, 124 - 127, web_of_scienceInternational conference proceedings

Exotic atoms and exotic nuclei

In this article, we briefly review the study of the exotic atoms and exotic nuclei, and report on recent research activities of eta-mesic nucleus and kaonic atoms., WYDAWNICTWO UNIWERSYTETU JAGIELLONSKIEGO, 2015, Acta Phys. Polon. B, 46 (1), 121 - 126, doi;web_of_scienceScientific journal

Formation spectra of pionic atoms in the Green's function method

We study the formation spectra of deeply bound pionic atoms in the (d, He-3) reactions using the Green's function method, stimulated by recent developments in experimental techniques. The Green's function method is considered to be a better theoretical formalism than the effective number approach to evaluate the formation rate of unstable systems. We compare the calculated results by the Green's function method with those by the effective number approach in various cases. We find that the differences between the results obtained by both methods are reasonably small and we can reaffirm that the effective number approach is a good theoretical method for the analyses of the previous experimental data with typical binding-energy errors of Delta B. E. greater than or similar to 20 keV for the deeply bound pionic atoms. On the other hand, we think that theoretical results using the Green's function method will be necessary in the near future to deduce precise information on the pion properties in nuclei from analyses of the pionic atom data with better accuracy than before., OXFORD UNIV PRESS INC, 2015, PTEP, 2015 (3), 033D01, doi;web_of_scienceScientific journal

Formation of Deeply Bound Pionic Atoms and Pion Properties in Nuclei

We study theoretically the formation of deeply bound pionic atoms to deduce the pion properties in nuclei precisely from the observables. We show the theoretical formation spectra of deeply bound pionic atoms in the various cases. We consider the pionic atom formation on the even-even and neutron-odd nucleus targets. We also show the angular dependence of the formation spectra in the (d, He-3) reactions. Based on these theoretical results, we have found that we can obtain the systematic information on several deeply bound states for various nuclei. Actually, these observations have been performed in the experiments at RIBF/RIKEN., POLISH ACAD SCIENCES INST PHYSICS, 2015, Acta Phys. Polon. A, 127 (5), 1568 - 1570, doi;web_of_scienceScientific journal

Spectroscopy of $η'$-nucleus bound states at GSI and FAIR — very preliminary results and future prospects —

The possible existence of eta'-nucleus bound states has been put forward through theoretical and experimental studies. It is strongly related to the eta' mass at finite density, which is expected to be reduced because of the interplay between the U (A) (1) anomaly and partial restoration of chiral symmetry. The investigation of the C(p,d) reaction at GSI and FAIR, as well as an overview of the experimental program at GSI and future plans at FAIR are discussed., SPRINGER, 2015, Hyperfine Interact., 234 (1-3), 33 - 39, doi;web_of_scienceScientific journal

Meson properties from mesic atoms and mesic nuclei

Meson properties are believed to have close connection to the fundamental theory, QCD, and have been studied for a long time both theoretically and experimentally. In this report, we study the recent activities in this field and consider the eta(958) mesic nuclei and the deeply bound pionic atoms. We summarize the possible formation of the eta(958) mesic nuclei by the (p, d) reactions and report the new possibilities of the spectroscopic study of the pionic atoms using the (d,He-3) reactions., E D P SCIENCES, 2014, EPJ Web Conf., 81, 01026 - 01026, doi;web_of_scienceScientific journal

Experimental constraints on the \ensuremathω –nucleus real potential

In a search for omega mesic states, the production of omega-mesons in coincidence with forward going protons has been studied in photon induced reactions on C-12 for incident photon energies of 1250-3100 MeV. The pi(0)gamma pairs from decays of bound or quasi-free omega-mesons have been measured with the CBELSA/TAPS detector system in coincidence with protons registered in the MiniTAPS forward array. Structures in the total energy distribution of the pi(0)gamma pairs, which would indicate the population and decay of bound omega B-11 states, are not observed. The pi(0)gamma cross section of 0.3 nbMeV(-1) sr(-1) observed in the bound state energy regime between -100 and 0 MeV may be accounted for by yield leaking into the bound state regime because of the large in-medium width of the omega-meson. A comparison of the measured total energy distribution with calculations suggests the real part V-0 of the omega B-11 potential to be small and only weakly attractive with V-0(rho = rho(0)) = -15 +/- 35(stat) +/- 20(syst) MeV in contrast to some theoretical predictions of attractive potentials with a depth of 100-150 MeV. (C) 2014 The Authors. Published by Elsevier B.V., ELSEVIER SCIENCE BV, 2014, Phys. Lett. B, 736, 26 - 32, doi;web_of_scienceScientific journal

Elementarity of composite systems

The "compositeness" or "elementarity" is investigated for s-wave composite states dynamically generated by energy-dependent and independent interactions. The bare mass of the corresponding fictitious elementary particle in an equivalent Yukawa model is shown to be infinite, indicating that the wave function renormalization constant Z is equal to zero. The idea can be equally applied to both resonant and bound states. In a special case of zero-energy bound states, the condition Z = 0 does not necessarily mean that the elementary particle has the infinite bare mass. We also emphasize arbitrariness in the "elementarity" leading to multiple interpretations of a physical state, which can be either a pure composite state with Z = 0 or an elementary particle with Z not equal 0. The arbitrariness is unavoidable because the renormalization constant Z is not a physical observable., AMER PHYSICAL SOC, 2014, Phys. Rev. C, 90 (6), 065201 - 065201, doi;web_of_scienceScientific journal

Meson Properties at Finite Density from Mesic Atoms and Mesic Nuclei

The properties of eta'(958) meson at finite nuclear density is considered to have close connection with the effects of U-A(1) anomaly at finite density. In this context, we are very much interested in the study of the eta'(958)mesic nuclei. As for the eta-mesic nuclei, which have been studied for a long time, we think it is interesting and important to consider both effects of the coupling of eta N system to N*(1535) and of the mixing of eta with eta'(958). In this article, we briefly summarize recent results of our studies concerning with eta'(958)- and eta-mesic nuclei., WYDAWNICTWO UNIWERSYTETU JAGIELLONSKIEGO, 2014, Acta Phys. Polon. B, 45 (3), 619 - 619, doi;web_of_scienceScientific journal

Missing Mass Spectroscopy of $η'$ Mesic Nuclei with the $(p,d)$ Reaction at GSI

We plan a missing-mass spectroscopy experiment of eta' mesic nuclei with the C-12(p,d)eta'circle times C-11 reaction to study in-medium properties of the eta' meson. In nuclear medium, due to restoration of chiral symmetry, the mass of the eta' meson may be reduced, and 71 bound states in a nucleus may exist. The experiment will be started at GSI with a 2.5 GeV proton beam using FRS as a spectrometer and will be continued at Super-FRS at FAIR. The plan of the experiment and development of a Cherenkov detector and an optics mode are described., E D P SCIENCES, 2014, EPJ Web Conf., 66, 09019 - 09019, doi;web_of_scienceScientific journal

Spectroscopy of eta-prime Mesic Nuclei via Semi-Exclusive Measurement at FAIR

In order to investigate a possible mass reduction of an eta' meson at finite density, a series of missing-mass spectroscopy experiments of rl-nucleus bound states with the C-12(p,d) reaction is planned at GSI and FAIR. A semi-exclusive measurement with the tagging of protons from eta' two-body absorption (eta'NN -> NN) will be a key feature in an experiment with Super-FRS at FAIR., E D P SCIENCES, 2014, EPJ Web Conf., 66, 09006 - 09006, doi;web_of_scienceScientific journal

Formation of η'(958)-mesic nuclei by the (p,d) reaction

We calculate theoretically the formation spectra of η'(958)-nucleus systems in the (p,d) reaction for the investigation of in-medium modification of the η' mass. We show comprehensive numerical calculations based on a simple form of the η' optical potential in nuclei with various potential depths. We conclude that one finds evidence of a possible attractive interaction between η' and the nucleus as a peak structure appearing around the η' threshold in light nuclei such as 11C, when the attractive potential is stronger than 100 MeV and the absorption width is of order 40 MeV or less. Spectroscopy of the (p,d) reaction is expected to be performed experimentally at existing facilities, such as GSI. We also estimate the contributions from the ω and ρ mesons, which have masses close to the η' meson, concluding that the observation of the peak structure of the η'-mesic nuclei is not disturbed, although their contributions may not be small. © 2013 American Physical Society., American Physical Society, 02 Apr. 2013, Physical Review C - Nuclear Physics, 87 (4), doiScientific journal

Resonances generated by the vector meson-baryon dynamics

We have recently studied vector meson-octet baryon (VB) interactions with the aim to find dynamical generation of resonances in such systems. For this, we consider the s-, t-, u-channel diagrams along with a contact interaction originating from the hidden local symmetry Lagrangian. We find the contribution from all these sources, except the s-channel, to be important. The amplitudes obtained by solving the coupled channel Bethe-Salpeter equations for the systems with total strangeness zero show generation of one isospin 3/2, spin 1/2 resonance and three isospin 1/2 resonances: two with spin 3/2 and one with spin 1/2. We identify these resonances with Δ (1900) S31, N*(2080) D13, N* (1700) D13, and N*(2090) S11, respectively. Further, we briefly discuss the results of our investigation of the VB systems when coupled to the pseudoscalar meson-baryon (PB) channels. We find that the low-lying resonances couple strongly to the VB channels, a result which can be useful in studying the reactions involving pseudoscalar and vector meson exchanges. In case of the higher mass resonances (in the 1,800-2,200 MeV region), we find that some of the states claimed as dynamically generated states in the VB system can disappear due to their coupling to the PB channels. We also find that new states can appear from PB-VB coupled channel dynamics for example, we find that a Σ resonance near 1,400 MeV gets developed due to such an effect. © 2012 Springer-Verlag., 2013, Few Body Syst., 54 (1-4), 343 - 346, doiScientific journal

Composite and elementary components in hadron resonances

In hadron resonances different structures of hadronic composite (molecule) and elementary (quark-intrinsic) natures may coexist. We sketch discussions based on our previous publications on the origin of hadron resonances (Hyodo et al. Phys. Rev. C 78:025203, 2008) on exotic D̄(B) meson-nucleons as candidates of hadronic composites (Yamaguchi et al. Phys. Rev. D 84:014032, 2011) and on a1 for the coexistence/mixing of the two different natures (Nagahiro et al. Phys. Rev. D 83:111504, 2011). © 2012 Springer-Verlag., 2013, Few Body Syst., 54 (1-4), 19 - 24, doi;url;urlScientific journal

Formation of $η^\prime(958)$-mesic nuclei by ($p,d$) reaction

We calculate theoretically the formation spectra of. n' (958)-nucleus systems in the (p,d) reaction for the investigation of in-medium modification of the. n' mass. We show comprehensive numerical calculations based on a simple form of the. n' optical potential in nuclei with various potential depths. We conclude that one finds evidence of a possible attractive interaction between. n' and the nucleus as a peak structure appearing around the. n' threshold in light nuclei such as C-11, when the attractive potential is stronger than 100 MeV and the absorption width is of order 40 MeV or less. Spectroscopy of the (p, d) reaction is expected to be performed experimentally at existing facilities, such as GSI. We also estimate the contributions from the omega and phi mesons, which have masses close to the. n' meson, concluding that the observation of the peak structure of the. n' -mesic nuclei is not disturbed, although their contributions may not be small., AMER PHYSICAL SOC, 2013, Phys. Rev. C, 87 (4), 045201 - 045201, doi;web_of_scienceScientific journal

Composite and elementary nature of a resonance in the \ensuremathσ model

We analyze the mixing nature of the low-lying scalar resonance consisting of the pi pi composite and the elementary particle within the sigma model. A method to disentangle the mixing is formulated in the scattering theory with the concept of the two-level problem. We investigate the composite and elementary components of the sigma meson by changing a mixing parameter. We also study the dependence of the results on model parameters such as the cut-off value and the mass of the elementary sigma meson., AMER PHYSICAL SOC, 2013, Phys. Rev. C, 88 (5), 055203 - 055203, doi;web_of_scienceScientific journal

(d,3He) reaction on odd-neutron nuclear target for the formation of deeply bound pionic atoms

We consider pionic atom spectroscopy by the (d,He-3) reaction on an odd-neutron nuclear target in this article, which has not yet been investigated. In the (d,He-3) reaction on the odd-neutron nuclear target, we can observe pionic states in the even-neutron nucleus with spin-parity 0(+). We expect that these pionic states do not have additional shifts due to the effects of the residual interaction between neutron-hole and pionic states. For the even-neutron nuclear target cases, we may have to take into account the residual interaction effects to deduce the binding energies of the pionic states precisely from the high-precision experimental data, since the final pionic states are pion-particle plus neutron-hole [pi circle times n(-1)] states. Thus, in addition to widening the domain of pionic atom spectroscopy on the nuclear chart, the present study of the (d,He-3) reaction on an odd-neutron target is considered to be important to deduce extremely precise information on the binding energies of the observed pionic states, and to clarify the pion properties and aspects of the symmetries of the strong interaction at finite density. We modify the formula of the even-even nuclear target case to study pionic atom formation spectra on the even-odd nuclear target and show the numerical results of the Sn-117 target case. This experiment will be performed at RIBF/RIKEN in the near future., OXFORD UNIV PRESS INC, 2013, PTEP, 2013 (6), 063D01, 1-15, doi;web_of_scienceScientific journal

Complex 2D matrix model and geometrical map on the complex-$N_c$ plane

We study the parameter dependence of the internal structure of resonance states by formulating a complex two-dimensional (2D) matrix model, where the two dimensions represent two levels of resonances. We calculate a critical value of the parameter at which a "nature transition" with character exchange occurs between two resonance states, from the viewpoint of geometry on complex-parameter space. Such a critical value is useful for identifying the internal structure of resonance states with variation of the parameter in the system.We apply the model to analyze the internal structure of hadrons with variation of the color number Nc from∞to a realistic value 3. By regarding 1/Nc as the variable parameter in our model, we calculate a critical color number of the nature transition between hadronic states in terms of a quark-antiquark pair and a mesonic molecule as exotics from the geometry on the complex-Nc plane. For large-Nc effective theory, we employ the chiral Lagrangian induced by holographic QCD with a D4/D8/D8 multi-D brane system in type IIA superstring theory. © The Author(s) 2013., 2013, PTEP, 2013 (8), 083D01, 1-13, doiScientific journal

Formation of the $η^\prime$(958)-mesic nuclei in missing mass spectroscopies

We calculate the formation cross section of the eta'-mesic nuclei by (pi, N) and (p, d) reactions based on the latest theoretical considerations of the eta' properties in nucleus. The results shown here are important to give predictions and support for future experiments and to establish the connection between the eta' mesic nucleus formation spectra and the modifications of the eta' properties at finite density, which will give us new information on the eta' mass generation mechanism. (C) 2013 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV, 2013, Nucl. Phys. A, 914, 360 - 364, doi;web_of_scienceScientific journal

$η^\prime$ meson under partial restoration of chiral symmetry in nuclear medium

In-medium modification of the eta' mass is discussed in the context of partial restoration of chiral symmetry in nuclear medium. We emphasize that the U-A (1) anomaly effects cause the eta'-eta mass difference necessarily through the chiral symmetry breaking. As a consequence, the eta' mass is expected to be reduced by order of 100 MeV in nuclear matter where about 30% reduction of chiral symmetry takes place. The strong attraction relating to the eta' mass generation eventually implies that there should be also a strong attractive interaction in the scalar channel of the eta'-N two-body system. We find that the attraction can be strong enough to form a bound state. (C) 2012 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV, 2013, Nucl. Phys. A, 914, 354 - 359, doi;web_of_scienceScientific journal

Nuclear density probed by anti-kaon-nucleus systems and anti-kaon-nucleus interaction

Effective nuclear densities probed by anti-kaon-nucleus systems is studied theoretically both for bound and low energy scattering states. As for the bound states, we investigate kaonic atoms. We find that the effective density depends on the atomic states significantly and we have the possibility to obtain the anti-kaon properties at various nuclear densities by observing the several kaonic atom states. We also find the energy dependence of the probed density by scattering states. We find that the study of the effective nuclear density will help to find the proper systems to investigate the meson properties at various nuclear densities. (C) 2013 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV, 2013, Nucl. Phys. A, 914, 344 - 348, doi;web_of_scienceScientific journal

Formation of $η'(958)$ Meson Bound States and Chiral Symmetry In-Medium

We theoretically discuss the feasibility to observe the eta'(958)-mesic nuclei by using the missing mass spectroscopy. We evaluate the eta'-nucleus optical potential including the contribution of lowest order in density together with the second order terms account for eta' absorption by two nucleons, based on a recent model of the eta'N interaction. We show the calculated formation cross section of the eta' bound states from (pi, N) reaction with pion beam momentum p (pi) = 1.8 GeV/c and (p, d) reaction with proton kinetic energy T (p) = 2.5 GeV., SPRINGER WIEN, 2013, Few Body Syst., 54 (7-10), 1565 - 1568, doi;web_of_scienceScientific journal

Formation of Deeply Bound Pionic Atoms in Sn Isotopes

We study the formation of deeply bound pionic atoms in the (d,He-3) reaction theoretically. At different scattering angles, we find that the different subcomponents dominate the formation spectra because of the matching condition of the reaction. We also find that the pionic 1s state which is free from the residual interaction effects appears clearly in Sn-117(d, He-3) spectra. We conclude that the observation of the (d,He-3) reaction for these new cases will provide more systematic and accurate information on the pionic bound states, and it will help to develop the study of the pion properties and the partial restoration of chiral symmetry in nuclei., SPRINGER WIEN, 2013, Few Body Syst., 54 (7-10), 1573 - 1576, doi;web_of_scienceScientific journal

Spectroscopy of $η'$ mesic nuclei with $(p,d)$ reaction

We are going to perform an inclusive spectroscopy experiment of eta' mesic nuclei with the C-12(p,d) reaction to study in-medium properties of the eta' meson. In nuclear medium, the eta' meson mass may be reduced due to partial restoration of chiral symmetry. In case of sufficiently large mass reduction and small absorption width of eta' at normal nuclear density, peak structures of eta' mesic states in C-11 will be observed near the eta' emission threshold even in an inclusive spectrum. The experiment will be carried out at GSI with proton beam supplied by SIS using FRS as a spectrometer. The detail of the experiment is described., SPRINGER WIEN, 2013, Few Body Syst., 54 (7-10), 1263 - 1266, doi;web_of_scienceScientific journal

Dynamically Generated Resonances from Two Vectors in the Charm Sector and their Decays

In this talk we study dynamically generated resonances from two-vector mesons within the hidden gauge formalism in a coupled channel unitary approach. We focus on the sectors with charm and/or strangeness and double charm, being some of them flavor exotic. Concretely, by looking for poles in the complex plane, we get three poles in the T-matrix around 2,460, 2,640 and 2,572 MeV that we identify with the and , coupling strongly to D*rho (the first two) and D*K* respectively. In addition, we obtain resonances in other exotic sectors such as (charm = 1; strangeness = -1), (charm = 2; strangeness = 0, 1). This 'flavor-exotic' states are interpreted as and molecular states and have not been observed yet. The observation of these peculiar states is a challenge for the experimentalist., SPRINGER WIEN, 2013, Few Body Syst., 54 (7-10), 1259 - 1262, doi;web_of_scienceScientific journal

Formation of deeply bound pionic atoms in Sn isotopes

We study the formation of deeply bound pionic atoms in the (d,He-3) reactions theoretically and show the energy spectra of the emitted He-3 at finite angles. We find that the different combinations of the pion-bound and neutron-hole states dominate the formation spectra at different scattering angles because of the matching condition of the reaction. We conclude that the observation of the (d,He-3) reaction at finite angles will provide the systematic information of the pionic bound states in each nucleus, and it will help to develop the study of the pion properties and the partial restoration of chiral symmetry in nuclei., E D P SCIENCES, 2012, EPJ Web Conf., 37, 09018 - 09018, doi;web_of_scienceScientific journal

eta' meson under partial restoration of chiral symmetry in nuclear medium

We shed light upon the eta ' mass in nuclear matter in the context of partial restoration of chiral symmetry, pointing out that the U-A ( 1) anomaly effects causes the eta '-eta mass difference necessarily through the chiral symmetry breaking As a consequence, it is expected that the eta ' mass is reduced by order of 100 MeV in nuclear matter where partial restoration of chiral symmetry takes place. The discussion given here is based on Ref. [1], E D P SCIENCES, 2012, EPJ Web Conf., 37, 09019 - 09019, arxiv;doi;web_of_science;url;urlScientific journal

Formation of eta-prime(958) mesic nuclei

In this report, we show the theoretical results of the formation spectra of the η′-nucleus systems in the (p,d) reactions based on the latest theoretical considerations of the η′ properties in nucleus. The results shown here are important to give predictions and supports to the future experiment, and to make clear relations between the η′ mesic nucleus formation spectra and the modifications of the η′ properties at finite density, which will give us new information on the η′ mass generation mechanism., 2012, EPJ Web Conf., 37, 02001 - 02001, doi;url;urlScientific journal

Hadron resonances with coexistence of different natures

We discuss coexistence/mixing of different natures of hadronic composite (molecule) and elementary (quark-intrinsic) ones in hadron resonances. The discussions here are based on our previous publications on the origin of hadron resonances [1], exotic $\\bar{D}$ meson-nucleons as hadronic composites containing one anti-heavy quark [2], and the study of a1 as a typical example to show explicitly the mixing of the two different natures [3]. In all cases, interactions are derived from the chiral dynamics of the light flavor sector. These interactions generate in various cases hadronic composite/molecule states, serving varieties of structure beyond the conventional quark model. © Owned by the authors, published by EDP Sciences, 2012., 2012, EPJ Web Conf., 20, 01005 - 01005, arxiv;doi;url;urlScientific journal

Spectroscopy of eta'-nucleus bound states at GSI-SIS

The η′ meson mass may be reduced due to partial restoration of chiral symmetry. If this is the case, an η′-nucleus system may form a nuclear bound state. We plan to carry out a missing-mass spectroscopy experiment with the 12C(p,d) reaction at GSI-SIS. Peak structures corresponding to such a bound state may be observed even in an inclusive measurement, if the decay width is narrow enough., 2012, EPJ Web Conf., 37, 02005 - 02005, doi;url;urlScientific journal

Feasibility Study of Observing eta' Mesic Nuclei with (p,d) Reaction

A novel method is proposed to measure eta' (958) meson bound states in C-11 nuclei by missing mass spectroscopy of the C-12(p, d) reaction near the eta' production threshold. It is shown that peak structures will be observed experimentally in an inclusive measurement in case that the in-medium eta' mass reduction is sufficiently large and that the decay width of eta' mesic states is narrow enough. Such a measurement will be feasible with the intense proton beam supplied by the SIS synchrotron at GSI combined with the good energy resolution of the fragment separator FRS., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, 2012, Prog. Theor. Phys., 128 (3), 601 - 613, web_of_science;doiScientific journal

Nuclear bound state of eta'(958) and partial restoration of chiral symmetry in the eta' mass

The in-medium mass of the eta' meson is discussed in a context of partial restoration of chiral symmetry in nuclear medium. The eta' mass is expected to be reduced by an order of 100 MeV at the saturation density. The reduction is a consequence of the suppression of the anomaly effect on the eta' mass induced by partial restoration of chiral symmetry. This strong attraction in eta' nuclear systems does not accompany large absorption of eta' into nuclear matter. This leads to the possibility of so narrow bound states of the eta' meson in nuclei to be seen in hadronic reactions with light nuclear targets., AMER PHYSICAL SOC, 2012, Phys. Rev. C, 85 (3), 032201 - 032201, doi;web_of_scienceScientific journal

eta-prime nucleus optical potential and possible eta-prime bound states

Starting from a recent model of the eta'N interaction, we evaluate the eta'-nucleus optical potential, including the contribution of lowest order in density, t rho/2m(eta'), together with the second-order terms accounting for eta' absorption by two nucleons. We also calculate the formation cross section of the eta' bound states from (pi(+), p) reactions on nuclei. The eta'-nucleus potential suffers from uncertainties tied to the poorly known eta'N interaction, which can be partially constrained by the experimental modulus of the eta'N scattering length and/or the recently measured transparency ratios in eta' nuclear photoproduction. Assuming an attractive interaction and taking the claimed experimental value vertical bar a(eta'N)vertical bar = 0.1 fm, we obtain an eta' optical potential in nuclear matter at saturation density of V eta' = -(8.7 + 1.8i) MeV, not attractive enough to produce eta' bound states in light nuclei. Larger values of the scattering length give rise to deeper optical potentials, with moderate enough imaginary parts. For a value vertical bar a(eta'N)vertical bar = 0.3 fm, which can still be considered to lie within the uncertainties of the experimental constraints, the spectra of light and medium nuclei show clear structures associated to eta'-nuclear bound states and to threshold enhancements in the unbound region. (C) 2012 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV, 2012, Phys. Lett. B, 709 (1-2), 87 - 92, doi;web_of_scienceScientific journal

Vector- and Pseudoscalar-baryon coupled channel systems

In this manuscript, I will report the details of our recent work on the vector meson-baryon (VB) interaction, which we studied with the motivation of finding dynamical generation of resonances in the corresponding systems. We started our study by building a formalism based on the hidden local symmetry and calculating the leading order contributions to the scattering equations by summing the diagrams with: (a) a vector meson exchange in the t-channel (b) an octet baryon exchange in the s-, u-channels and (c) a contact interaction arising from the part of the vector meson-baryon Lagrangian which is related to the anomalous magnetic moment of the baryons. We find the contribution from all these sources, except the s-channel, to be important. The amplitudes obtained by solving the coupled channel Bethe-Salpeter equations for the systems with total strangeness zero, show generation of one isospin 3/2, spin 1/2 resonance and three isospin 1/2 resonances: two with spin 3/2 and one with spin 1/2. We identify these resonances with Delta (1900) S-31, N* (2080) D-13, N* (1700) D-13, and N* (2090) S-11, respectively. We have further extended our study by including pseudoscalar meson-baryon (PB) as the coupled channels of VB systems. For this, we obtain the PB -> VB amplitudes by using the Kroll-Ruddermann term where, considering the vector meson dominance phenomena, the photon is replaced by a vector meson. The calculations done within this formalism reveal a very strong coupling of the VB channels to the low-lying resonances like Lambda (1405) and Lambda (1670), which can have important implications on certain reactions producing them. In addition to this, we find that the effect of coupling the higher mass states to the lighter channels is not restricted to increasing the width of those states, it can be far more strong., IOP PUBLISHING LTD, 2012, J. Phys. Conf. Ser., 374, 012007 - 012007, doi;web_of_scienceScientific journal

Pionic atom spectroscopy in the (d,3 He) reaction at finite angles

We study the formation of deeply bound pionic atoms in the (d, He-3) reactions theoretically and show the energy spectra of the emitted He-3 at finite angles, which are expected to be observed experimentally. We find that the different combinations of the pion-bound and neutron-hole states dominate the spectra at different scattering angles because of the matching condition of the reaction. We conclude that the observation of the (d, He-3) reaction at finite angles will provide the systematic information of the pionic bound states in each nucleus and will help to develop the study of the pion properties and the partial restoration of chiral symmetry in nuclei., Springer Science and Business Media LLC, Dec. 2011, The European Physical Journal A, 47 (12), 161 - 161, doi;web_of_science;url;url;urlScientific journal

Vector meson-baryon interaction to study dynamical generation of resonances

With the motivation to find dynamical generation of resonances, we study vector-meson baryon interaction by taking s-, t-, u-channel diagrams and a contact interaction into account. A comparison of the different contributions obtained from these diagrams is done in the SU(2) limit, which shows that these diagrams could be equally important. We find it worthwhile to pay attention to the structure of the total interaction between the two non-zero spin particles which possess similar masses and find spin dependent interaction similar to the nucleon-nucleon case., AMER INST PHYSICS, 2011, AIP Conf. Proc., 1388 (1), 310 - 313, doi;web_of_scienceScientific journal

A study of mixing properties of a1(1260) meson

We develop a practical method to analyze the mixing structure of hadrons consisting of two components of quark composite and hadronic composite by taking the a(1)(1260) meson as an example. We also make reference to the large N-c procedure and its limitation for the classification of such a mixed state., AMER INST PHYSICS, 2011, AIP Conf. Proc., 1388 (1), 302 - 305, doi;web_of_science;url;urlScientific journal

Structure and formation of eta- and pi-nucleus systems

In this article, we review recent research activities on the structure and formation of the eta mesic nuclei and the pionic atoms., AMER INST PHYSICS, 2011, AIP Conf. Proc., 1388 (1), 495 - 501, doi;web_of_science;url;urlScientific journal

Decay of vector-vector resonances into $γ$ and a pseudoscalar meson

We study the decay of dynamically generated resonances from the interaction of two vectors into a gamma and a pseudoscalar meson. The dynamics requires anomalous terms involving vertices with two vectors and a pseudoscalar, which renders it special. We compare our result with data on K(2)*(+) (1430) -> K(+) gamma and K(2)*(0) (1430) -> K(0) gamma and find a good agreement with the data for the K(2)*(+) (1430) case and a width considerably smaller than the upper bound measured for the K(2)*(0) (1430) meson. We also investigate the decay into pi(+) gamma of one a(2) state, tentatively associated to the a(2)(1320), obtaining qualitative agreement with data., AMER PHYSICAL SOC, 2011, Phys. Rev. D, 83 (9), 094030 - 094030, doi;web_of_scienceScientific journal

Composite and elementary natures of $a_1(1260)$ meson

We develop a practical method to analyze the mixing structure of hadrons consisting of two components of quark composite and hadronic composite. As an example, we investigate the properties of the axial vector meson a(1)(1260) and discuss its mixing properties quantitatively. We also make reference to the large N-c procedure and its limitation for the classification of such a mixed state., AMER PHYSICAL SOC, 2011, Phys. Rev. D, 83 (11), 111504 - 111504, doi;web_of_scienceScientific journal

Precision Spectroscopy of Deeply Bound Pionic Atoms and Partial Restoration of Chiral Symmetry in Medium

We study theoretically the formation spectra of deeply bound pionic atoms expected to be observed by experiments with high energy resolution at RIBF/RIKEN, and we discuss in detail the possibilities to extract new information on the pion properties at finite density from the observed spectra, which may provide information on partial restoration of chiral symmetry in medium. We find that the non-yrast pionic states such as 2s are expected to be seen in the (d,He-3) spectra, which will be helpful to reduce uncertainties of the theoretical calculations in the neutron wave functions in nucleus. The observation of the 2s state with the ground is state is also helpful to reduce the experimental uncertainties associated in the calibration of the absolute excitation energy. We find that the nuclear densities probed by atomic pions are quite stable and almost constant for various atomic states and various nuclei. Effects of the pion wave function renormalization to the formation spectra are also evaluated., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, 2011, Prog. Theor. Phys., 126 (3), 483 - 509, doi;web_of_scienceScientific journal

Formation of Heavy Meson Bound States by Two Nucleon Pick-up Reactions

We develop a model to evaluate the formation rate of the heavy mesic nuclei in two-nucleon pick-up reactions and apply it to the (6)Li target cases for the formation of heavy meson-alpha bound states, as examples. The existence of the quasideuteron in the target nucleus is assumed in this model. It is found that mesic nuclei formation in recoilless kinematics is possible even for heavier mesons than the nucleon in two-nucleon pick-up reactions. We find the formation rate of the meson-alpha bound states can be around half of the elementary cross sections at the recoilless kinematics with small distortions., AMER PHYSICAL SOC, 2011, Phys. Rev. C, 84 (5), 054609 - 054609, doi;web_of_scienceScientific journal

A theoretical model for formation of eta- He-4 bound state by d + d reaction

In this article, we consider theoretically the d+d reaction for the formation of the eta-He-4 bound state. We evaluate the formation rate and show expected spectra using a simple theoretical model with Green's function method., WORLD SCIENTIFIC PUBL CO PTE LTD, 2011, Int. J. Mod. Phys. A, 26 (3-4), 444 - 449, doi;web_of_scienceScientific journal

Formation of η-mesic nuclei by (π, N) reaction at J-PARC

We study the formations of of the η-nucleus systems in the (πN) reactions with nuclear targets, which can be performed at existing and/or forthcoming facilities, including the Japan Proton Accelerator Research Complex, to investigate the η-nucleus interaction. Based on the N*(1535) dominance in the ηN system, the η-mesic nuclei are suitable systems for the study of in-medium properties of the N*(1535) baryon resonance, such as reduction of the mass difference of N and N* in the nuclear medium, which affects the level structure of the η and N*-hole modes. We find that clear information on the in-medium N*- and η-nucleus interactions can be obtained through the formation spectra of the η-mesic nuclei., World Scientific Publishing Co., 01 Jan. 2010, Hadron and Nuclear Physics 09: Osaka University, Japan, 16-19 November 2009, 141 - 149, doiIn book

Regge approach in charged k* photoproduction

We investigate ϒp → K*+A reaction within a Regge approach. For the gauge invariance of the scattering amplitude, we reggeize the s-channel and contact term amplitudes as well as the t-channel amplitude. We obtain the decreasing behavior of the total cross section as the CLAS's preliminary data show. We also calculate spin density matrices, and find clear differences between our Regge model and the previous Feynman (isobar) model., World Scientific Publishing Co., 01 Jan. 2010, Hadron and Nuclear Physics 09: Osaka University, Japan, 16-19 November 2009, 188 - 192, doiIn book

Meson properties in nuclear medium

We discuss the interests and difficulties of the studies of the meson-nucleus bound systems. As recent topics, we briefly explain the research activities of the deeply bound pionic atoms, the η'(958) mesic nuclei, and the ϕ mesic nuclei., World Scientific Publishing Co., 01 Jan. 2010, Hadron and Nuclear Physics 09: Osaka University, Japan, 16-19 November 2009, 134 - 140, doiIn book

Deeply bound pionic states in Sn at RIKEN RI beam factory

We study the structure of pionic atoms in l21Sn, for which a new experiment will be performed at RIKEN RI Beam Factory. We evaluate numerically the effective nuclear densities probed by pion and potential parameter dependence of the binding energies and widths., World Scientific Publishing Co., 01 Jan. 2010, Hadron and Nuclear Physics 09: Osaka University, Japan, 16-19 November 2009, 206 - 210, doi;url;urlIn book

Charged K* Photoproduction in a Regge model

We investigate the gamma p -> K*(+)Lambda reaction within a Regge approach. For the gauge invariance of the scattering amplitude, we reggeize the s channel and contact-term amplitudes as well as the t-channel amplitude. We obtain a decreasing behavior of the total cross section as the CLAS's preliminary data show. We also calculate spin density matrices and find clear differences between our Regge model and the previous Feynman (isobar) model., AMER PHYSICAL SOC, 2010, Phys. Rev. C, 81 (3), 035206 - 035206, doi;web_of_scienceScientific journal

Theoretical study of formation rates of eta-, eta'- and omega-mesic nuclei induced by the pion beam

We present the theoretical study on formation rates of the eta-, eta'- and omega-meson-nucleus systems induced by the (pi, N) reactions on nuclear targets. For the eta-mesic nuclei, we can study the in-medium properties of the N*(1535) baryon resonance. As for the eta'(958) meson-nucleus system, the in-medium U(A) (1) anomaly effect might be observed. We can also know the in-medium behavior of the omega meson by the (pi, N) reaction with nuclear targets. We conclude that valuable information on mesons in the medium can be extracted from global structures of the missing mass spectra in the (pi, N) reaction., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, 2010, Prog. Theor. Phys. Suppl., 186 (186), 316 - 324, doi;web_of_scienceScientific journal

Phi photoproduction in a coupled-channel approach

We investigate photoproduction of phi-mesons off protons within a coupled-channel effective-Lagrangian method which is based on the K-matrix approach. We take into account pi N, rho N, eta N, K Lambda, K Sigma, K Lambda (1520) and phi N channels. Especially we focus on K Lambda(1520) channel. We also introduce a nucleon resonance which couples to phi N and K Lambda (1520) channels. We find that coupled-channel effects are not sizable at very forward angle (theta = 0) and the resonance can reproduce a peak structure of the correct magnitude at the right energy. We also investigate the effects of coupled channels and the resonance on the angular distribution for phi-photoproduction., ELSEVIER SCIENCE BV, 2010, Nucl. Phys. A, 835 (1-4), 321 - 324, doi;web_of_scienceScientific journal

Scalar, Axial-Vector and Tensor Resonances from the $ρ D^*$, $ω D^*$ Interaction in the Hidden Gauge Formalism

We apply a unitary approach together with a set of hidden-gauge Lagrangians to study the vector-vector interaction. We study the case of the p(omega)D* interaction within the model. In I = 1/2 we get strong enough attraction to bind the system. Concretely, we get one resonance for each spin J = 0,1,2. For J = 1 and 2 these resonances can be easily identified with the D* (2460) and D* (2640). Whereas the state for J = 0 with mass M similar to 2600 MeV is a prediction of the model. In I = 3/2 we get a repulsive interaction and hence no exotic dynamically generated states., AMER INST PHYSICS, 2010, AIP Conf. Proc., 1257 (1), 447 - 451, web_of_science;doiScientific journal

Formation of \eta -Mesic Nuclei

In this paper, we briefly introduce the interests and the recent research activities on the eta-mesic nuclei. We also mention the activities on the eta'(958)-mesic nucleus formation., POLISH ACAD SCIENCES INST PHYSICS, 2010, Acta Phys. Polon. B, 41 (10), 2211 - 2220, web_of_scienceScientific journal

Reaction dynamics for photoproductions of baryon resonances

The study of exotic structure of hadrons is fully achieved when reaction dynamics of the associated hadron productions is well understood. We employ as the standard mechanism the effective Lagrangian method and investigate several physical observables within the framework. The parameters are constrained by microscopic description of hadrons. We discuss photoproductions of kaon associated with the ground state Λ(1116) and its resonances Λ(1405) and Λ(1520). In the former example we emphasize the meson cloud effect which significantly renormalizes the phenomenological parameters, while in the latter we discuss the features of the standard method. Finally we discuss briefly the production of ηπ associated with the nucleon resonance N(1535) for the study of chiral symmetry of baryons. © 2009 Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd., 2009, Chin. Phys. C, 33 (12), 1167 - 1174, doi;url;urlScientific journal

Formation of eta-mesic nuclei by (pi, N) reaction and chiral symmetry for baryons

We calculate formation spectra of eta-nucleus systems in (pi, N) reactions with nuclear targets, which can be performed at existing and/or forthcoming facilities, including J-PARC, in order to investigate eta-nucleus interactions. Based on the N*(1535) dominance in the eta N system, eta-mesic nuclei are suitable systems for study of in-medium properties of the N* (1535) baryon resonance, such as reduction of the mass difference of N and N* in nuclear medium, which affects level structure of the eta and N*-hole modes. We find that clear information on the in-medium N*- and eta-nucleus interactions can be obtained through the formation spectra of the eta-mesic nuclei., WORLD SCIENTIFIC PUBL CO PTE LTD, 2009, Int. J. Mod. Phys. E, 18 (10), 2202 - 2206, doi;web_of_scienceScientific journal

Special Issue: Proceedings for the International Workshop on Chiral Symmetry in Hadron and Nuclear Physics (CHIRAL07) PREFACE

WORLD SCIENTIFIC PUBL CO PTE LTD, Sep. 2008, MODERN PHYSICS LETTERS A, 23 (27-30), V - VII, web_of_sciencePhoto- and Electron-Production of Mesons on Nucleons and Nuclei

In these lectures I will show some results obtained with the chiral unitary approach applied to the photo- and electro-production of mesons. The results for the photo-production of eta pi(0)p and K-0 pi(0)Sigma(+), together with related reactions will be shown, having with common denominator the excitation of the Delta(1700) resonance which is one of those dynamically generated in the chiral unitary approach. Then I will show the results obtained for the e(+)e(-) -> phi f(0)(980) reaction which reproduce the bulk of the data except for a pronounced peak, giving support to a new mesonic resonance, X(2175). Results will also be shown for the electromagnetic form factors of the N* (1535) resonance, also dynamically generated in this approach. Finally, I will show some results on the photo-production of the omega in the nuclei, showing that present experimental results claiming a shift of the omega mass in the medium are tied to a particular choice of background and are not conclusive. On the other hand, the same experimental results show unambiguously a huge increase of the omega width in the nuclear medium. (c) 2007 Elsevier B.V. All fights reserved., ELSEVIER SCIENCE BV, 2008, Prog. Part. Nucl. Phys., 61 (1), 260 - 275, doi;web_of_scienceScientific journal

Modern Physics Letters A: Preface

2008, Modern Physics Letters A, 23 (27-30), v-viiStructure and formation of kaonic atoms and kaonic nuclei

We study theoretically the in-flight (K-, N) reactions for the formation of (K) over bar NN systems using the microscopic chiral unitary s-wave (K) over barN amplitude to get deeper physical insights on the expected spectra, and to investigate the experimental feasibility of the reaction at J-PARC facility. We show the missing mass spectra of the (K-, N) reactions accompanied by the particle emissions due to (K) over barK absorption in nucleus., WORLD SCIENTIFIC PUBL CO PTE LTD, 2008, Mod. Phys. Lett. A, 23 (27-30), 2528 - 2531, web_of_science;doiScientific journal

Study of in-medium properties of N*(1535) and chiral symmetry for baryons through the eta-mesic nuclei formation at J-PARC

We investigate the properties of eta-nucleus interaction by postulating the N*(1535) dominance for eta-N system. We evaluate the N*(1535) properties in the nuclear medium using two kinds of chiral models, and find that these two models provide qualitatively different eta-nucleus optical potentials reflecting the quite distinct properties of N*(1535) in these chiral models. Especially, in the chiral doublet model, we can expect to have the level crossing between eta and N*(1535)-hole which is expected to provide the characteristic features for the optical potential and the formation spectra. We find also that the difference of these models can be seen in the formation cross sections of the eta mesic nuclei with (pi(+),p) reaction expected to be performed at J-PARC project., WORLD SCIENTIFIC PUBL CO PTE LTD, 2008, Mod. Phys. Lett. A, 23 (27-30), 2512 - 2515, doi;web_of_scienceScientific journal

The role of the QCD anomaly in kaon photoproduction

We study the kaon photoproduction associated with the production of the ground state Lambda. We investigate the role of K and K* exchange in the t-channel, which can be tested by the photon asymmetry in comparison with experimental data. We find a significant amount of contribution from the one-loop diagram induced by the gauged Wess-Zumino-Witten term for QCD anomaly. This enable us to use coupling constants which are determined in a microscopic way, unlike the previous phenomenological studies where the K* coupling strengths were treated as a free parameter., WORLD SCIENTIFIC PUBL CO PTE LTD, 2008, Mod. Phys. Lett. A, 23 (27-30), 2325 - 2328, doi;web_of_scienceScientific journal

Magnetic interaction induced by the anomaly in kaon-photoproductions

We study the role of magnetic interaction in the photoproduction of the kaon and hyperon. We find that the inclusion of a higher order diagram induced by the Wess-Zumino-Witten term has a significant contribution to the magnetic amplitude, which is compatible to the observed photon asymmetry in the forward angle region. This enables us to use the K* coupling constants which have been determined in a microscopic way rather than the phenomenological ones which differ largely from the microscopic ones. (C) 2008 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV, 2008, Phys. Lett. B, 665 (4), 178 - 181, doi;web_of_scienceScientific journal

Formation of deeply bound kaonic atoms in (K-,N) reactions

We study theoretically the (K-,N) reactions for the formation of the deeply bound kaonic atoms, which were predicted to be quasistable with narrow widths, using the Green's function method. We systematically consider various cases with different target nuclei and energies and find clear signals in the theoretical spectra for all cases considered in this article. The signals show very interesting structures, such as a RESONANCE DIP instead of a resonance peak. We discuss the origins of the interesting structures and the possibilities of obtaining new information on the existence of kaonic nuclei from the spectra of atomic state formations. © 2007 The American Physical Society., 31 Oct. 2007, Physical Review C - Nuclear Physics, 76 (4), doiScientific journal

Photoproduction of omega and omega in the nuclear medium

Oct. 2007Scientific journal

Exotic mesic atoms for a class of strongly correlated fermi systems

NOVA SCIENCE PUBLISHERS, INC, 2007, CONDENSED MATTER THEORIES, VOL 21, 21, 351 - +, web_of_scienceInternational conference proceedings

Formation of Deeply Bound Kaonic Atoms in (K-,N) Reactions

We study theoretically the (K-,N) reactions for the formation of the deeply bound kaonic atoms, which were predicted to be quasistable with narrow widths, using the Green's function method. We systematically consider various cases with different target nuclei and energies and find clear signals in the theoretical spectra for all cases considered in this article. The signals show very interesting structures, such as a RESONANCE DIP instead of a resonance peak. We discuss the origins of the interesting structures and the possibilities of obtaining new information on the existence of kaonic nuclei from the spectra of atomic state formations., AMER PHYSICAL SOC, 2007, Phys. Rev. C, 76 (4), 045204 - 045204, doi;web_of_scienceScientific journal

Study of possible omega bound states in nuclei with the (gamma,p) reaction

We perform calculations for omega production in nuclei by means of the (gamma,p) reaction for photon energies and proton angles suited to currently running and future experiments in present laboratories. For some cases of possible omega optical potentials, we find that clear peaks are observable when a good resolution in the omega energy is available. We also study the inclusive production of pi(0)gamma in nuclei around the omega energy and find a double hump structure for the energy spectra, with a peak around a pi(0)gamma energy of m(omega)-100 MeV, which could easily be misidentified by a signal of an omega bound state in nuclei, while it is actually due to a different scaling of the uncorrelated pi(0)gamma production and omega production with subsequent pi(0)gamma decay., AMERICAN PHYSICAL SOC, 2007, Phys. Rev. C, 75 (6), 064616 - 064616, doi;web_of_scienceScientific journal

eta- and eta '-mesic nuclei and U-A(1) anomaly at finite density

We discuss theoretically the possibility of observing the bound states of the eta and eta(')(958) mesons in nuclei. We apply the NJL model to study the eta and eta(') meson properties at finite density and calculate the formation cross sections of the eta and eta(') bound states with the Green function method for (gamma,p) reaction. We also discuss the experimental feasibility at photon facilities like SPring-8. The contributions due to the omega meson production are also included to obtain the realistic (gamma,p) spectra. We conclude that we can expect to observe resonance peaks in (gamma,p) spectra for the formation of meson bound states and we can deduce new information on eta and eta(') properties at finite density. These observations are believed to be essential to know the possible mass shift of eta(') and deduce new information on the effective restoration of the U-A(1) anomaly in the nuclear medium., AMER PHYSICAL SOC, Oct. 2006, PHYSICAL REVIEW C, 74 (4), 045203, doi;web_of_scienceScientific journal

eta- and eta-prime-mesic nuclei and U(A)(1) anomaly at finite density

We discuss theoretically the possibility of observing the bound states of the η and η'(958) mesons in nuclei. We apply the NJL model to study the η and η' meson properties at finite density and calculate the formation cross sections of the η and η' bound states with the Green function method for (γ,p) reaction. We also discuss the experimental feasibility at photon facilities like SPring-8. The contributions due to the ω meson production are also included to obtain the realistic (γ,p) spectra. We conclude that we can expect to observe resonance peaks in (γ,p) spectra for the formation of meson bound states and we can deduce new information on η and η' properties at finite density. These observations are believed to be essential to know the possible mass shift of η' and deduce new information on the effective restoration of the UA(1) anomaly in the nuclear medium. © 2006 The American Physical Society., American Physical Society, 2006, Phys. Rev. C, 74 (4), 045203 - 045203, doiScientific journal

In-flight (K-,p) reactions for the formation of kaonic atoms and kaonic nuclei using the Green function method

We study theoretically the kaonic atom and kaonic nucleus formations in the in-flight (K-,p) reactions using the Green function method, which is suited to evaluate formation rates both of stable and unstable bound systems. We consider C12 and O16 as the targets and calculate the spectra of the (K-,p) reactions. We conclude that no peak structure resulting from kaonic nucleus formation is expected in the reaction spectra calculated with the chiral unitary kaon-nucleus optical potential. In the spectra with the phenomenological deep kaon-nucleus potential, it may be possible to observe some structures because of the formation of the kaonic nucleus states. For all cases, we find clear signals because of the kaonic atom formations in the reaction spectra, which show very interesting structures, such as the RESONANCE DIP instead of the resonance peak for the atomic 1s state formation. © 2006 The American Physical Society., American Physical Society, 2006, Physical Review C - Nuclear Physics, 74 (1), doiScientific journal

eta-prime(958)-mesic nuclei formation and U(1)A anomaly at finite density

We discuss the possibility of producing the bound states of the eta'(958) meson in nuclei theoretically using the the Nambu-Jona-Lasinio (NJL) model. We calculate the formation cross section of the eta' bound states with the Green function method for the (gamma,p) reaction and discuss the experimental feasibility at photon facilities such as SPring-8. We conclude that we can expect to observe resonance peaks in (gamma,p) spectra for the formation of eta' bound states and we can deduce new information on eta' properties at finite density. These observations are believed to be essential to know the possible mass shift of eta' and deduce new information on the effective restoration of the chiral U-A (1) anomaly at finite density., AMER INST PHYSICS, 2006, AIP Conf. Proc., 842 (1), 228 - 230, web_of_science;doiScientific journal

In-flight (K-,p) reactions for the formation of kaonic atoms and kaonic nuclei in green function method

We study theoretically the kaonic atom and kaonic nucleus formations in the in-flight (K-,p) reactions using the Green function method, which is suited to evaluate formation rates both of stable and unstable bound systems. We consider C-12 and O-16 as the targets and calculate the spectra of the (K-,p) reactions. We conclude that no peak structure resulting from kaonic nucleus formation is expected in the reaction spectra calculated with the chiral unitary kaon-nucleus optical potential. In the spectra with the phenomenological deep kaon-nucleus potential, it may be possible to observe some structures because of the formation of the kaonic nucleus states. For all cases, we find clear signals because of the kaonic atom formations in the reaction spectra, which show very interesting structures, such as the RESONANCE DIP instead of the resonance peak for the atomic 1s state formation., AMER PHYSICAL SOC, 2006, Phys. Rev. C, 74 (1), 014604 - 014604, doi;web_of_scienceScientific journal

Formation of kaonic atoms and kaonic nuclei in in-flight (K-, p) reactions (vol 114, pg 301, 2005)

PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, Oct. 2005, PROGRESS OF THEORETICAL PHYSICS, 114 (4), 905 - 905, web_of_scienceResidual interaction effects on deeply bound pionic states in Sn and Pb isotopes

We have studied the residual interaction effects theoretically on the deeply bound pionic states in Pb and Sn isotopes. We need to evaluate the residual interaction effects carefully to deduce the nuclear medium effects for pion properties, which are believed to provide valuable information on nuclear chiral dynamics. The s- and p-wave pi N interactions are used for the pion-nucleon residual interactions. We show that the complex energy shifts are around [(10-20) + i(2-7)] keV for 1s states in Sn, which should be taken into account in the analyses of the high precision data of deeply bound pionic 1s states in Sn isotopes., AMER PHYSICAL SOC, Jun. 2005, PHYSICAL REVIEW C, 71 (6), doi;web_of_scienceScientific journal

Production of circle dot(+) hypernuclei with the (K+,pi(+)) reaction

We investigate the formation cross sections of the Theta(+)-hypernuclei theoretically. In the (K+,pi(+)) reaction, we obtain the excitation spectra with clearly differentiated peaks corresponding to the Theta(+) bound states., WORLD SCIENTIFIC PUBL CO PTE LTD, 2005, Pentaquark 04, Proceedings, 378 - 385, web_of_scienceInternational conference proceedings

Formation of kaonic atoms and kaonic nuclei by in-flight (K-,p) reactions

We theoretically study kaonic atom and kaonic nucleus formation in in-flight (K-,p) reactions for C, O, Si and Ca targets. Deeply bound kaonic atoms were previously predicted to exist as quasi-stable states, and it is expected that they can be observed using certain well-suited experimental methods. Kaonic nuclear states have also been predicted to exist with large decay widths. We evaluate the formation cross sections of kaonic atoms and kaonic nuclei using an effective number approach. We show that indications of kaonic bound states can be observed in the outgoing proton energy spectra., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, 2005, Prog. Theor. Phys., 114 (2), 301 - 316, doi;web_of_scienceScientific journal

Residual interaction effects on deeply bound pionic states in Sn and Pb isotopes

We have studied the residual interaction effects theoretically on the deeply bound pionic states in Pb and Sn isotopes. We need to evaluate the residual interaction effects carefully to deduce the nuclear medium effects for pion properties, which are believed to provide valuable information on nuclear chiral dynamics. The s- and p-wave πN interactions are used for the pion-nucleon residual interactions. We show that the complex energy shifts are around [(10-20) + i(2-7)] keV for 1s states in Sn, which should be taken into account in the analyses of the high precision data of deeply bound pionic 1s states in Sn isotopes. © 2005 The American Physical Society., 2005, Phys. Rev. C, 71 (6), 061601 - 061601, doiScientific journal

In-medium properties of N*(1535) in chiral models and eta-nucleus interaction

We investigate the properties of η-nucleus interaction by postulating the N*(1535) dominance for η-N system. We evaluate the N*(1535) properties in the nuclear medium using two kinds of chiral models, and find that these two models provide qualitatively different η-nucleus optical potential reflecting the quite distinct properties of N*(1535) in these chiral models. We find also that the difference of these models can be seen in the formation cross sections of the η mesic nuclei with (d, 3He) and (γ,p) reactions, which are expected to be distinguishable in experiments. © 2005 Elsevier B.V. All rights reserved., Elsevier, 2005, Nucl. Phys. A, 755 (1-4), 491 - 494, doi;url;urlScientific journal

Formation of eta-prime(958) - mesic nuclei and axial U(A)(1) anomaly at finite density

We discuss the possibility of producing the bound states of the eta(')(958) meson in nuclei theoretically. We calculate the formation cross sections of the eta(') bound states with the Green function method for the (gamma,p) reaction and discuss the experimental feasibility at photon facilities such as SPring-8. We conclude that we can expect to observe resonance peaks in (gamma,p) spectra for the formation of eta(') bound states and we can deduce new information on eta(') properties at finite density. These observations are believed to be essential to know the possible mass shift of eta(') and deduce new information on the effective restoration of the chiral U-A(1) anomaly in the nuclear medium., AMERICAN PHYSICAL SOC, 2005, Phys. Rev. Lett., 94 (23), 232503 - 232503, doi;web_of_scienceScientific journal

Formation of mesic nuclei by (gamma,p) reactions

We present a theoretical study on formation rates of eta and omega meson-nucleus systems induced by (gamma, p) reactions on nuclear targets at ideal recoilless condition. We find that the smaller distortion effect in the (gamma, p) reaction enables us to investigate properties of the mesons created deeply inside nucleus more clearly. We also consider excitation of scalar-isoscalar (sigma) mode in nucleus in order to investigate spectral enhancement around two-pion threshold caused by partial restoration of chiral symmetry. We conclude that valuable information of meson-nucleus interactions can be extracted from global structure of the missing mass spectra in the (gamma, p) reaction. (c) 2005 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV, 2005, Nucl. Phys. A, 761 (1-2), 92 - 119, doi;web_of_scienceScientific journal

Production of Theta+ hypernuclei with the (K+, pi+) reaction

We present results on the production of bound states of Theta(+) in nuclei using the (K+, pi(+)) reaction. By taking into account the states obtained within a wide range of strength of the Theta(+) nucleus optical potential, plus the possibility to replace different nucleons of the nucleus, we obtain an excitation spectra with clearly differentiated peaks. The magnitude of the calculated cross sections is well within reachable range. (c) 2005 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV, 2005, Phys. Lett. B, 620 (3-4), 125 - 130, doi;web_of_scienceScientific journal

eta-mesic nuclei in chiral models

The properties of η-nucleus interaction and their experimental consequences are investigated with η-nucleus optical potentials obtained by postulating the N*(1535) dominance for η-N system. The N*(1535) properties in the nuclear medium are evaluated by two kinds of chiral effective models based on distinct pictures of N*(1535). We find that these two models provide qualitatively different optical potentials of the η meson, reflecting the different in-medium properties of N*(1535) expected in these two models. In order to compare these models in physical observables, we calculate spectra of (d,3He) reactions for the η mesic nucleus formation with various kinds of target nuclei. We show that the (d, 3He) spectra obtained in these models are significantly different and are expected to be distinguishable in experiments., Yukawa Institute for Theoretical Physics, 2004, Prog. Theor. Phys. Suppl., 153, 340 - 343, doi;url;urlScientific journal

η-nucleus interactions and in-medium properties ofN*(1535)in chiral models

The properties of [Formula Presented]-nucleus interaction and their experimental consequences are investigated with [Formula Presented]-nucleus optical potentials obtained by postulating the [Formula Presented] dominance for [Formula Presented] system. The [Formula Presented] properties in the nuclear medium are evaluated by two kinds of chiral effective models based on distinct pictures of [Formula Presented] We find that these two models provide qualitatively different optical potentials of the [Formula Presented] meson, reflecting the in-medium properties of [Formula Presented] in these models. In order to compare these models in physical observables, we calculate spectra of [Formula Presented] reactions for the [Formula Presented] mesic nucleus formation with various kinds of target nuclei. We show that the [Formula Presented] spectra obtained in these models are significantly different and are expected to be distinguishable in experiments. © 2003 The American Physical Society., American Physical Society (APS), 17 Sep. 2003, Physical Review C, 68 (3), 9, doi;j_global;url;urlScientific journal

Medium effects to the N(1535) resonance and eta mesic nuclei

The structure of η-nucleus bound systems (η mesic nuclei) is investigated as one of the tools to study in-medium properties of the N(1535) (N*) resonance. We show that, as a general consequence, the η-nucleus potential has a repulsive core at the nuclear center with an attractive part at the nuclear surface, if sufficient reduction of the mass difference of N and N* stems from the in-medium effects to N*. The (d,3He) spectra are evaluated for the formation of these bound states to investigate the experimental feasibility., Elsevier, 2003, Nucl. Phys. A, 721, 665 - 668, arxiv;doi;url;urlScientific journal

Medium effects to the [Formula Presented] resonance and [Formula Presented] mesic nuclei

The structure of [Formula Presented]-nucleus bound systems [Formula Presented] mesic nuclei) is investigated as one of the tools to study in-medium properties of the [Formula Presented] resonance by using the chiral doublet model to incorporate the medium effects of the [Formula Presented] resonance in a chiral symmetric way. We find that the shape and depth of the [Formula Presented]-nucleus optical potential are strongly affected by the in-medium properties of the [Formula Presented] and nucleon. Especially, as a general feature of the potential, the existence of a repulsive core of the [Formula Presented]-nucleus potential at the nuclear center with an attractive part at the nuclear surface is concluded. We calculate the level structure of bound states in this “central-repulsive and surface-attractive” optical potential and find that the level structure is sensitive to the in-medium properties of the [Formula Presented] The [Formula Presented] spectra are also evaluated for the formation of these bound states to investigate the experimental feasibility. We also make comments on the possible existence of halo-like [Formula Presented] states in [Formula Presented]-unstable halo nuclei. © 2002 The American Physical Society., 2002, Physical Review C - Nuclear Physics, 66 (4), 7, doiScientific journal

Binding energy of scalar bound state by topologically massive interaction: fermion and anti-fermion system with heavy mass

A bound state problem in a topologically massive quantum electrodynamics is investigated by using a non-perturbative method. We formulate the Bethe-Salpeter equation for scalar bound states composed of massive fermion and anti-fermion pair under the lowest ladder approximation. In a large mass expansion for the (anti-)fermion, we derive the Schrodinger equation and solve it by a numerical method. The energy eigenvalues of bound states are evaluated for various values of a topological mass and also a fermion mass. Then we find a novel logarithmic scaling behaviour of the binding energy m varying the topological mass, fermion mass and also a quantum number. There exists a critical value of the topological mass, beyond which the bound states disappear. As the topological mass decreases, the energy eigenvalues of the bound states, which are negative, also decrease with a logarithmic dependence on the topological mass. A Chern-Simons term gives the bound system a repulsive effect. (C) 2002 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV, 2002, Phys. Lett. B, 536 (1-2), 49 - 58, doi;web_of_scienceScientific journal

Formation of sigma mesic nuclei in (d,t) and (d,He-3) reactions

We explore the possibility to observe an enhanced 2π correlation in the scalar-isoscalar (σ) channel in nuclei by (d, t) and (d, 3He) reactions to obtain new information on the partial restoration of chiral symmetry in the nuclear medium. The sensitivity of the reaction spectra on the change of the chiral condensate in the nuclear medium is examined. © 2002 Elsevier Science B.V. All rights reserved., 2002, Nucl. Phys. A, 710 (1-2), 131 - 144, doiScientific journal

Topological mass versus dynamical mass: Novelty in (2+1)-dimensional space-time

2000, Grav. Cosmol., 6, 145 - 145Scientific journal

Formation of sigma mesic nuclei as a probe of chiral restoration in nuclear medium

2000, Soryushiron Kenkyu, 102 (5), 185 - 190Scientific journal

Eta-Prime Bound States in Nuclei and Partial Restoration of Chiral Symmetry

14th International Conference on Hadron Spectroscopy, arxiv;url;url

(p,d)反応の分光によるη′中間子原子核の探索

24 Mar. 2015, 日本物理学会講演概要集(CD-ROM), 70 (1), ROMBUNNO.21PCC-1, j_globalThe structure of baryons. Proceedings, 12th International Conference, Baryons'10,

2011, AIP Conf. Proc., 1388Hadron and nuclear physics 09: Osaka University, Japan, 16-19 November 2009

This volume collects papers presented at the international workshop "Hadron-Nuclear Physics 09" held at Osaka, November 16-19, 2009. The series of this workshop has provided opportunities to discuss common interests of hadron and nuclear physics. Hadrons and nuclei show up different layers of phenomena governed by the same dynamics dictated by the fundamental law of the strong interaction, Quantum Chromodynamics (QCD). The basic building blocks of matter, quarks and gluons, are confined in hadrons, generating their masses dynamically and breaking chiral symmetry spontaneously. The latter is the origin of the presence of the pion which governs the essential part of the nuclear interaction. Therefore, the common key words are chiral symmetry and pions. This volume contains reports of current achievements in hadron physics including exotic multiquark states, meson production reactions and non-linear dynamics of hadrons, and those in nuclear physics clustering phenomena, exotic neutron rich nuclei and the pions in nuclei. As related subjects, applications to astronuclear physics, including accelerator physics and laser physics are also discussed comprehensively., World Scientific Publishing Co., 01 Jan. 2010, Hadron and Nuclear Physics 09: Osaka University, Japan, 16-19 November 2009, 1 - 407, doi;urlOthers

Hadron and Nuclear Physics 09, Proceedings of International Workshop on Hadron and Nuclear Physics, "HNP09"

2010, World ScientificChiral symmetry in hadron and nuclear physics. Proceedings, International Workshop, CHIRAL07, Osaka, Japan, November 13-16, 2007.

2008, Modern Physic Letters A, 23, 2201-2623

Structure of charmed baryons studied by pionic decays

Structures and Interactions of Heavy Quark Hadrons, Mar. 2017Effect of the final state interaction of eta'N on the eta' photoproduction off nucleon

第72回日本物理学会年次大会, Mar. 2017Structure of charmed baryons studied by pionic decays

2016 JAEA/ASRC Reimei Workshop : New exotic hadron matter at J-PARC, Oct. 2016, Koreaチャームバリオン励起状態の構造とパイオン放出に崩壊

日本物理学会, Sep. 2016Decays of charmed baryons through pion emission in the quark model

The 10th APCTP-BLTP/JINR-RCNP-RIKEN Joint Workshop on Nuclear and Hadron Physics, Aug. 2016, RIKENDecays of charmed baryons through pion emission in the quark model

Seminar at IFIC, Valencia University, Jul. 2016Formation of possible eta'(958)-nucleus bound states and eta'N interaction

The 14th Internatioanal Conference on Meson-Nucleon Physics and the Structure of the Nucleon (MENU2016), Jul. 2016Decays of charmed baryons through pion emission in the quark model

日本物理学会 第71回年次大会, Mar. 2016Decays of charmed baryons through pion emission in the quark modek

Mini-Workshop on hadron physics with a variety of flavors, Feb. 2016チャームバリオンの崩壊／Mesic nuclei by missing mass specroscopy

二国間交流事業共同研究／セミナー, Feb. 2016結合チャネル計算によるeta'(958)核子相互作用

原子核媒質中のハドロン研究 III, Oct. 2015クォーク模型によるチャームバリオンの崩壊 --パイオン放出過程-

日本物理学会 2015年秋季大会, Sep. 2015eta'(958)-nucleon interaction and possible bound state of eta'N system

1st Hadron Spanish Network Days and Spanish-Japanese JSPS Workshop, Jun. 2015Hadron properties at finite density and specroscopies of mesic nuclei

Hadrons and Hadron Interaction in QCD2015 -Effective Theory and Lattice -, Mar. 2015Elementarity of composite systems

Workshop on "Bound states in QCD and beyond", Mar. 2015, St. Goar, GermanyStudy for the elementarity of composite systems

4th Joint Meeting of the Nuclear Physics Division of the American Physical Society and The Physical Soci ety of Japan, Oct. 2014, American Physical Society and Japan Physical SocietyFormation of eta'(958) mesic nuclei by (p,d) reaction

EXA2014, Sep. 2014Do elementary particle survive composite systems ?

The 8th APCTP-BLTP JINR Joint Workshop, Jun. 2014Composite and elementary natures of hadron resonances

Hirschegg2014, International Workshop XLII on Gross Properties of Nuclei and Nuclear Excitations, Jan. 2014, Hirschegg, Kleinwalsertal, Austriaeta'(958)-nucleus bound states and their formations by missing mass spectroscopies

YITP workshop on "Hadrons in Nucleus", Nov. 2013, Maskawa Hall, Kyoto Universityeta'(958) mesic nuclei by (p,d) reaction

MesonNet Meeting, Jun. 2013, Prague, Czech RepublicStudy of mixing properties of mesonic resonances

第68回日本物理学会年次大会, Mar. 2013, 広島大学東広島キャンパスFormation of eta'(958) nucleus bound state

ELPH研究会ダブルメソン生成とバリオン分光, Nov. 2012, 東北大学電子光理学研究センター, 宮城県仙台市東北大学Formation of the eta'(958)-mesic nuclei in missing mass specroscopies

XI International Conference on Hypernuclear and Strange Particle Physics, Oct. 2012, Barcelona University, Barcelona, SPAINFormation of eta'(958) mesic nuclei by missing mass spectroscopy

Seminar talk at Technische Universitat Munchen, Oct. 2012, Technische Universitat Munchen, ドイツ・ミュンヘンFormation of eta'(958) mesic nuclei by the (p,d) reaction at GSI

Seminar talk at GSI, Sep. 2012, GSI, ダルムシュタット、ドイツFormation of the eta'(958) meson bound states and chiral symmetry in-meidum

The 20th International IUPAP Conference on Few-Body Problems in Physics (FB20), Aug. 2012, IUPAP, Kyushu University, 福岡市国際会議場Composite and elementary natures of mesonic resonances

新学術領域「素核宇宙融合」×「新ハドロン」クロスオーバー研究会--多彩な手法でせまるハドロン物理への挑戦--, Jul. 2012, 新学術領域素核宇宙融合、新ハドロン、名古屋大学, 名古屋大学eta'(958)中間子に対する二核子吸収の評価とeta'中間子原子核生成

第67回日本物理学会年次大会, Mar. 2012Formation spectra of eta' mesic nuclei by the (p,d) reaction

eta' in-medium workshop, Feb. 2012Formation of eta'(958) meson bound states in nuclei at J-PARC

Workshop on:\nFuture Prospects of Hadron Physics at J-PARC\nand Large Scale Computational Physics, Feb. 2012eta'(958) meson bound states and their formations

Workshop on:_x000B_ "Elucidation of New Hadrons with a Variety of Flavors“_x000B_- Grant-in-Aid for Scientific Research on Innovative Areas ?, Feb. 2012Composite and elementary natures of hadrons -- Study of mixing properties of a1(1260) --

Composite and elementary natures of hadrons -- Study of mixing properties of a1(1260) --, Jun. 2011