Researchers Database

TAKAHASHI Tomohiko

    Faculty Division of Natural Sciences Research Group of Physics Professor
Contact:
tomocc.nara-wu.ac.jp
Last Updated :2021/10/01

researchmap

Research Interests

  • 弦の場の理論 弦理論 素粒子論 Theoretical Particle Physics 

Research Areas

  • Natural sciences, Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics

Research Experience

  • Apr. 2019, Nara Women's University, Faculty, Division of Natural Sciences, 教授
  • Apr. 2012 Mar. - 2019, Nara Women's University, Faculty, Division of Natural Sciences, 准教授
  • Dec. 2010 Mar. - 2012, Nara Women's University, Faculty of Science, 准教授
  • Apr. 2007 Oct. - 2010, Nara Women's University, Faculty of Science, 助教
  • Apr. 2000 Mar. - 2007, Nara Women's University, Faculty of Science, 助手
  • Apr. 1997 Mar. - 2000, 日本学術振興会特別研究員 (PD・東京大学)

Education

  • Apr. 1992, Mar. - 1997, 京都大学大学院, 理学研究科, Japan
  • Apr. 1988, Mar. - 1992, Kobe University, Faculty of Science

Awards

  • 特別研究員等審査会専門委員(書面担当) 及び国際事業委員会書面審査員の表彰, 高橋 智彦, 日本学術振興会, Jul. 2015
  • 素粒子メダル奨励賞, 2007, JPN

Published Papers

  • Supersymmetric nonlinear sigma models as anomalous gauge theories

    Aya Kondo; Tomohiko Takahashi

    American Physical Society (APS), 16 Jul. 2020, Physical Review D, 102 (2), doi;url;url;rm:research_project_id

    Scientific journal

  • Two-point String Amplitudes Revisited by Operator Formalism

    Shigenori Seki; Tomohiko Takahashi

    So far we have considered that a two-point string amplitude vanishes due to the infinite volume of residual gauge symmetry. However recently Erbin-Maldacena-Skliros have suggested that the two-point amplitude can have non-zero value, because one can cancel the infinite volume by the infinity coming from on-shell energy conservation. They derived the two-point function by Fadeev-Popov method. In this paper we revisit this two-point string amplitude in the operator formalism. We find the mostly BRST exact operator which yields non-zero two-point amplitudes., 09 Sep. 2019, Phys. Lett. B, Volume 800, 135078 [arXiv:1909.03672], doi;arxiv;arxiv_url;arxiv_url

    Scientific journal

  • Closed string symmetries in open string field theory

    I. Kishimoto; T. Kitade; T. Takahashi

    Dec. 2018, Progress of Theoretical and Experimental Physics, 123B04, doi

    Scientific journal

  • Vector profile and gauge invariant observables of string field theory solutions for constant magnetic field background

    Nobuyuki Ishibashi; Isao Kishimoto; Toru Masuda; Tomohiko Takahashi

    We study profiles and gauge invariant observables of classical solutions corresponding to a constant magnetic field on a torus in open string field theory. We numerically find that the profile is not discontinuous on the torus, although the solution describes topologically nontrivial configurations in the context of low energy effective theory. From the gauge invariant observables, we show that the solution provide correct couplings of closed strings to a D-brane with constant magnetic field., Springer Verlag, 01 May 2018, Journal of High Energy Physics, 2018 (5), 144, doi

    Scientific journal

  • String field theory solution corresponding to constant background magnetic field

    Nobuyuki Ishibashi; Isao Kishimoto; Tomohiko Takahashi

    Following the method recently proposed by Erler and Maccaferri, we construct solutions to the equation of motion of Witten's cubic string field theory, which describe a constant magnetic field background. We study the boundary condition changing operators relevant to such a background, and calculate their operator product expansions. We obtain solutions whose classical action coincide with the Born-Infeld action., OXFORD UNIV PRESS INC, Jan. 2017, PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS, 013B06 (1), doi;web_of_science

    Scientific journal

  • Open string fields as matrices

    Isao Kishimoto; Toru Masuda; Tomohiko Takahashi; Shoko Takemoto

    We show that the action expanded around Erler-Maccaferri's N D-brane solution describes the N + 1 D-brane system where one D-brane disappears due to tachyon condensation. String fields on multi-branes can be regarded as block matrices of a string field on a single D-brane in the same way as matrix theories., OXFORD UNIV PRESS INC, Mar. 2015, PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS, 033B05 (3), doi;web_of_science

    Scientific journal

  • Observables for identity-based tachyon vacuum solutions

    Isao Kishimoto; Toru Masuda; Tomohiko Takahashi

    We consider a modified KBc algebra in bosonic open string field theory expanded around identity-based scalar solutions. By use of the algebra, classical solutions on the background are constructed and observables for them, including energy densities and gauge-invariant overlaps, are calculable. These results are applied to evaluate observables analytically for both the identity-based trivial pure gauge solution and the identity-based tachyon vacuum solution., OXFORD UNIV PRESS INC, Oct. 2014, PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS, 103B02 (10), doi;web_of_science

    Scientific journal

  • Comments on observables for identity-based marginal solutions in Berkovits' superstring field theory

    Isao Kishimoto; Tomohiko Takahashi

    We construct an analytic solution for tachyon condensation around identity-based marginal solutions in Berkovits' WZW-like open superstring field theory. Using this, which is a kind of wedge-based solution, the gauge invariant overlaps for the identity-based marginal solutions can be calculated analytically. This is a straightforward extension of a method in bosonic string field theory, which has been elaborated by the authors, to superstring. We also comment on a gauge equivalence relation between the tachyon vacuum solution and its marginally deformed one. From this viewpoint, we can find the vacuum energy of the identity-based marginal solutions to be zero, which agrees with the previous result as a consequence of xi zero mode counting., SPRINGER, Jul. 2014, JOURNAL OF HIGH ENERGY PHYSICS, 07(2014)031 (7), doi;web_of_science

    Scientific journal

  • Numerical solutions of open string field theory in marginally deformed backgrounds

    Isao Kishimoto; Tomohiko Takahashi

    We investigate numerical solutions of bosonic open string field theory in some marginally deformed backgrounds, which are obtained by expanding the action around an identity-based marginal solution with one parameter. We construct numerical solutions in the Siegel gauge and the Landau gauge corresponding to the tachyon vacuum. Their vacuum energy approximately cancels the D-brane tension for larger intervals of the parameter with increasing truncation level. The result is consistent with the previous expectation that the identity-based marginal solution has vanishing energy regardless of the values of the parameter. We also study the marginal branch (M-branch) and the vacuum branch (V-branch) and evaluate not only the vacuum energy but also the gauge invariant overlaps with the graviton and the closed tachyon. We observe that there is a finite bound for the value of the massless field of numerical solutions even in the marginally deformed background., OXFORD UNIV PRESS INC, Sep. 2013, PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS, 2013 (9), doi;web_of_science

    Scientific journal

  • Gauge invariant overlaps for identity-based marginal solutions

    Isao Kishimoto; Tomohiko Takahashi

    We investigate identity-based solutions associated with marginal deformations in open string field theory. We find that the identity-based marginal solutions can be represented as a difference of wedge-based solutions plus an integration of a deformed Becchi-Rouet-Stora-Tyutin exact state. Using this expression, the gauge invariant overlap can be calculated analytically for the identity-based solutions. Moreover, we show that, by gauge transformation, the overlap is transformed into a disk correlation function with the integrations of currents at the boundary. © The Author(s) 2013., Sep. 2013, Progress of Theoretical and Experimental Physics, 2013 (9), doi

    Scientific journal

  • Tachyon vacuum of bosonic open string field theory in marginally deformed backgrounds

    Shoko Inatomi; Isao Kishimoto; Tomohiko Takahashi

    We consider bosonic open string field theory in marginally deformed backgrounds, which is obtained by expanding the string field around identity-based solutions associated with marginal deformations. We find a new set of string fields that satisfies the K Bc algebra, but the nilpotent kinetic operator is that of the theory expanded around the identity-based marginal solution. By use of these string fields, we construct the tachyon vacuum solution in marginally deformed backgrounds. The vacuum energy density is equivalent to that of the tachyon vacuum without marginal deformations. The gauge invariant overlap is changed according to the effect of marginal deformations, as expected from known results in conformal field theory (CFT). These results suggest that the vacuum energy is zero for the identity-based marginal solutions in the original theory., OXFORD UNIV PRESS INC, Feb. 2013, PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS, 2013 (2), 023B02, doi;web_of_science

    Scientific journal

  • On nontrivial solutions around a marginal solution in cubic superstring field theory

    Shoko Inatomi; Isao Kishimoto; Tomohiko Takahashi

    We construct tachyon vacuum and half-brane solutions, using an extension of KBc algebra, in the theory around a type of identity-based marginal solutions in modified cubic superstring field theory. With explicit computations, we find that their vacuum energies are the same as those of corresponding solutions around the original theory. It implies that the vacuum energy for the identity-based marginal solution vanishes although straightforward computation of it is subtle. We also evaluate the gauge invariant overlaps for those nontrivial solutions. The values for them are deformed according to the marginal solution in the same way as the case of bosonic string field theory., SPRINGER, Dec. 2012, JOURNAL OF HIGH ENERGY PHYSICS, 12(2012) (12), 071, doi;web_of_science

    Scientific journal

  • Homotopy Operators and One-Loop Vacuum Energy at the Tachyon Vacuum

    Shoko Inatomi; Isao Kishimoto; Tomohiko Takahashi

    We construct homotopy operators for the BRST operator in the theory around identity-based solutions, which are believed to represent the tachyon vacuum in the cubic bosonic open string field theory. Using the homotopy operators, we find that the one-loop vacuum energy at the tachyon vacuum is independent of moduli such as interbrane distances, which are included in the BRST operator. We also revisit the cohomology problem, which was solved earlier without the homotopy operators., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, Dec. 2011, PROGRESS OF THEORETICAL PHYSICS, 126 (6), 1077 - 1089, doi;web_of_science

    Scientific journal

  • Homotopy operators and identity-based solutions in cubic superstring field theory

    Shoko Inatomi; Isao Kishimoto; Tomohiko Takahashi

    We construct a class of nilpotent operators using the BRST current and ghost fields in superstring theory. The operator can be realized in cubic superstring field theory as a kinetic operator in the background of an identity-based solution. For a particular type of the deformed BRST operators, we find a homotopy operator and discuss its relationship to the cohomology in a similar way to the bosonic case, which has been elaborated by the authors., SPRINGER, Oct. 2011, JOURNAL OF HIGH ENERGY PHYSICS, 2011 (10), 114, doi;web_of_science

    Scientific journal

  • A Vacuum Loop of an Open String around an Identity-Based Solution

    Tomohiko Takahashi

    We calculate a vacuum loop amplitude generated by a Siegel gauge propagator in the open string field theory expanded around the identity-based solution. We apply level truncation scheme to the calculation of the vacuum amplitude and find an approximate spectrum by its expansion form. The resulting spectrum is consistent with the absence of open strings at the tachyon vacuum., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, 2011, PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT, 188 (188), 163 - 168, doi;web_of_science

    Scientific journal

  • Exploring the vacuum structure near identity-based solutions

    I. Kishimoto; T. Takahashi

    We explore the vacuum structure in the bosonic open string field theory expanded near an identity-based solution parameterized by a (a parts per thousand yen -1/2). Analyzing the expanded theory using the level-truncation approximation up to the level 20, we find that the theory has the tachyon vacuum solution for a a parts per thousand yen -1/2. We also find that at a = -1/2, there exists an unstable vacuum solution in the expanded theory and the solution is expected to be the perturbative open string vacuum. These results reasonably support the hypothesis that the identity-based solution is a trivial pure gauge configuration for a > -1/2, but it can be regarded as the tachyon vacuum solution at a = -1/2., SPRINGER, Jun. 2010, THEORETICAL AND MATHEMATICAL PHYSICS, 163 (3), 717 - 724, doi;web_of_science

    Scientific journal

  • Numerical evaluation of gauge invariants for a-gauge solutions in open string field theory

    I. Kishimoto; T. Takahashi

    We evaluate gauge invariants (the action and the gauge-invariant overlap) for numerical solutions satisfying the "a-gauge" condition with various values of a in the cubic open bosonic string field theory. We use the level-truncation approximation and an iterative procedure to construct numerical solutions in the twist-even universal space. The resulting gauge invariants are numerically stable and almost equal to those of Schnabl's solution for tachyon condensation. Our result provides further evidence that these numerical and analytic solutions are gauge equivalent., SPRINGER, Jun. 2010, THEORETICAL AND MATHEMATICAL PHYSICS, 163 (3), 710 - 716, doi;web_of_science

    Scientific journal

  • Vacuum Structure around Identity-Based Solutions

    Isao Kishimoto; Tomohiko Takahashi

    We explore the vacuum structure in bosonic open string field theory expanded around an identity-based solution parameterized by a (>= -1/2). Analyzing the expanded theory using level truncation approximation up to level 14, we find that the theory has a stable vacuum solution for a > -1/2. The vacuum energy and gauge invariant overlap numerically approach those of the tachyon vacuum solution with increasing truncation level. We also find that, at a = -1/2, there exists an unstable vacuum solution in the expanded theory and it rapidly becomes the trivial zero configuration just above a = -1/2. The numerical behavior of the two gauge invariants suggests that the unstable solution corresponds to the perturbative open string vacuum. These results reasonably Support the expectation that the identity-based solution is a trivial pure gauge configuration for a > -1/2, but it can be regarded as the tachyon vacuum solution at a = -1/2., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, Aug. 2009, PROGRESS OF THEORETICAL PHYSICS, 122 (2), 385 - 399, doi;web_of_science

    Scientific journal

  • Numerical Evaluation of Gauge Invariants for a-Gauge Solutions in Open String Field Theory

    Isao Kishimoto; Tomohiko Takahashi

    We evaluate gauge invariants (vacuum energy and gauge invariant overlap) for numerical classical solutions in the cubic open string field theory under Asano and Kato's a-gauge fixing condition. We propose an efficient iterative procedure for solving the equations of motion so that the BRST invariance of the solutions is numerically ensured. The resulting gauge invariants are numerically stable and almost equal to those of Schnabl's tachyon vacuum solution in the well-defined region of a gauge parameter. These results provide further evidence that; the numerical and analytical solutions are gauge-equivalent., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, Apr. 2009, PROGRESS OF THEORETICAL PHYSICS, 121 (4), 695 - 710, doi;web_of_science

    Scientific journal

  • Gauge invariant overlaps for classical solutions in open string field theory

    Teruhiko Kawano; Isao Kishimoto; Tomohiko Takahashi

    We calculate gauge invariant observables for Schnabl's solution with analytic method and with the level truncation approximation. We also compute them for the numerical solution initially obtained by Sen and Zwiebach in the level truncation approximation to compare with the one for Schnabl's solution. The results are consistent with the expectation that they may be gauge equivalent. We briefly discuss the gauge invariant observables and the action for a marginal solution with a nonsingular current. (C) 2008 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV, Nov. 2008, NUCLEAR PHYSICS B, 803 (1-2), 135 - 165, doi;web_of_science

    Scientific journal

  • Schnabl's solution and boundary states in open string field theory

    Teruhiko Kawano; Isao Kishimoto; Tomohiko Takahashi

    We discuss that Schnabl's Solution is an off-shell extension of the boundary state describing a D-brane in the closed string sector. It gives the physical meaning of the gauge-invariant overlaps for the solution in our previous paper and supports Ellwood's recent proposal in the operator formalism. (C) 2008 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV, Nov. 2008, PHYSICS LETTERS B, 669 (5), 357 - 358, doi;web_of_science

    Scientific journal

  • Level truncation analysis of exact solutions in open string field theory

    Tomohiko Takahashi

    We evaluate vacuum energy density of Schnabl's solution using the level truncation calculation and the total action including interaction terms. The level truncated solution provides vacuum energy density expected both for tachyon vacuum and trivial pure gauge. We discuss the role of the phantom term to reproduce correct vacuum energy., SPRINGER, Jan. 2008, JOURNAL OF HIGH ENERGY PHYSICS, 0801 (1), 001, doi;web_of_science

    Scientific journal

  • Analytical tachyonic lump solutions in open superstring field theory

    Kishimoto, I; T Takahashi

    We construct a classical solution in the GSO(-) sector in the framework of a Wess-Zumino-Witten-like open superstring field theory on a non-BPS D-brane. We use an su(2) supercurrent, which is obtained by compactifying a direction to a circle with the critical radius, in order to get analytical tachyonic lump solutions to the equation of motion. By investigating the action expanded around a solution we find that it represents a deformation from a non-BPS D-brane to a D-brane-anti-D-brane system at the critical value of a parameter which is contained in classical solutions. Although such a process was discussed in terms of boundary conformal field theory before, our study is based on open superstring field theory including interaction terms., SPRINGER, Jan. 2006, JOURNAL OF HIGH ENERGY PHYSICS, 0601 (1), 013, doi;web_of_science

    Scientific journal

  • Exploring vacuum manifold of open string field theory

    Yuji Igarashi; Katsumi Itoh; Fumie Katsumata; Tomohiko Takahashi; Syoji Zeze

    The global symmetry generated by Kn is a subgroup of the stringy gauge symmetry. We explore the part of the vacuum manifold related by this symmetry. Strong evidence is presented that the analytic classical solutions to the cubic string field theory found earlier in Refs. 5) [T. Takahashi and S. Tanimoto, J. High Energy Phys. 03 (2002), 033 hep-th/0202133] and 6) [I. Kishimoto and T. Takahashi, Prog. Theor. Phys. 108 (2002), 591 hep-th/0205275] are actually related by the symmetry and, therefore, all of them describe the same tachyon vacuum. Some remaining subtlety is pointed out., Dec. 2005, Progress of Theoretical Physics, 114 (6), 1269 - 1293, doi

    Scientific journal

  • Marginal deformations and classical solutions in open superstring field theory

    Kishimoto, I; T Takahashi

    We construct a class of classical solutions in the Berkovits' open superstring field theory. The resulting solutions correspond to marginal boundary deformations in conformal field theory. The vacuum energy vanishes exactly for the solutions. Investigating the theory expanded around one of the solutions, we find that it reflects the effect of background Wilson lines. The solution has a well-defined Fock space expression and it is invariant under space-time supersymmetry transformation., SPRINGER, Nov. 2005, JOURNAL OF HIGH ENERGY PHYSICS, 0511 (11), 051, doi;web_of_science

    Scientific journal

  • Classical solutions and order of zeros in open string field theory

    Y Igarashi; K Itoh; F Katsumata; T Takahashi; S Zeze

    Earlier an analytic approach is proposed for classical solutions describing tachyon vacuum in open string field theory. Based on the approach, we construct a certain class of classical solutions written in terms of holomorphic functions with higher order zeros. Taking the simplest among the new classical solutions, we study the cohomology of the new BRS charge and make a numerical analysis of the vacuum energy. The results indicate that the new non-trivial solution is another analytic candidate for the tachyon vacuum., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, Sep. 2005, PROGRESS OF THEORETICAL PHYSICS, 114 (3), 695 - 706, doi;web_of_science

    Scientific journal

  • Marginal deformations and closed string couplings in open string field theory

    F Katsumata; T Takahashi; S Zeze

    We investigate analytic classical solutions in open string field theory which are constructed in terms of marginal operators. In the classical background, we evaluate a coupling between an on-shell closed string state and the open string field. The resulting coupling exhibits periodic behavior as expected from the marginal boundary deformation of background Wilson lines or a marginal tachyon lump. We confirm that the solutions in open string field theory correspond to a class of marginal deformations in conformal field theory., SPRINGER, Nov. 2004, JOURNAL OF HIGH ENERGY PHYSICS, 0411 (11), 050, doi;web_of_science

    Scientific journal

  • Tachyon condensation and universal solutions in string field theory

    T Takahashi

    We investigate a non-perturbative vacuum in open string field theory expanded around the analytic classical solution which has been found in the universal Fock space generated by matter Virasoro generators and ghost oscillators. We carry out level-truncation analyses up to level (6, 18) in the theory around one-parameter families of the solution. We observe that the value of the vacuum energy cancels the D-brane tension as the approximation level is increased, but this non-perturbative vacuum disappears at the boundary of the parameter space. These results provide strong evidence for the conjecture that, although the universal solutions are pure gauge in almost all the parameter space, they are regarded as the tachyon vacuum solution at the boundary. (C) 2003 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV, Oct. 2003, NUCLEAR PHYSICS B, 670 (1-2), 161 - 182, doi;web_of_science

    Scientific journal

  • Closed string amplitudes in open string field theory

    T Takahashi; S Zeze

    We investigate gauge invariant operators corresponding to on-shell closed string states in open string field theory. Using both oscillator representation and conformal mapping techniques, we calculate a two closed string tachyon amplitude that connects two gauge invariant operators by an open string propagator. We find that this amplitude is in a complete agreement with the usual disc amplitude., SPRINGER, Aug. 2003, JOURNAL OF HIGH ENERGY PHYSICS, 0308 (8), doi;web_of_science

    Scientific journal

  • Gauge fixing and scattering amplitudes in string field theory expanded around universal solutions

    T Takahashi; S Zeze

    We study a gauge fixed action of open string field theory expanded around the universal solution, which has been found as an analytic classical solution with one parameter, a. For a > -1/2, we are able to reproduce open string scattering amplitudes in the theory fixed in the Siegel gauge. At a = -1/2, all scattering amplitudes vanish and there is no open string excitation in the gauge fixed theory. These results support the conjecture that the universal solution can be regarded as a pure gauge or the tachyon vacuum solution., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, Jul. 2003, PROGRESS OF THEORETICAL PHYSICS, 110 (1), 159 - 177, doi;web_of_science

    Scientific journal

  • Open string field theory around universal solutions

    Kishimoto, I; T Takahashi

    We study the physical spectrum of cubic open string field theory around universal solutions, which are constructed using the matter Virasoro operators and the ghost and anti-ghost fields. We find the cohomology of the new BRS charge around the solutions, which appear with a ghost number that differs from that of the original theory. Considering the gauge-unfixed string field theory, we conclude that open string excitations. perturbatively disappear after the condensation of the string field to the solutions., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, Sep. 2002, PROGRESS OF THEORETICAL PHYSICS, 108 (3), 591 - 602, doi;web_of_science

    Scientific journal

  • Marginal and scalar solutions in cubic open string field theory

    T Takahashi; S Tanimoto

    We find marginal and scalar solutions in cubic open string field theory by using left-right splitting properties of a delta function. The marginal solution represents a marginal deformation generated by a U(1) current, and it is a generalized solution of the Wilson lines one given by the present authors. The scalar solution has a well-defined universal Fock space expression, and it is expressed as a singular gauge transform of the trivial vacuum. The expanded theory around it is unable to be connected with the original theory by the string field redefinition., SPRINGER, Mar. 2002, JOURNAL OF HIGH ENERGY PHYSICS, 0203 (3), 033, doi;web_of_science

    Scientific journal

  • Wilson lines and classical solutions in cubic open string field theory

    T Takahashi; S Tanimoto

    We construct exact classical solutions in cubic open string field theory. Through the redefinition of the string field, we find that the solutions correspond to finite deformations of the Wilson lines. The solutions have well-defined Fock space expressions, and they have no branch cut singularity of marginal parameters, which was found in the analysis using a level truncation approximation in the Feynman-Siegel gauge. We also discuss marginal tachyon lump solutions at critical radius., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, Oct. 2001, PROGRESS OF THEORETICAL PHYSICS, 106 (4), 863 - 872, doi;web_of_science

    Scientific journal

  • Open-closed string field theory in a background B field

    T Kawano; T Takahashi

    In this paper, we study open-closed string field theory in a background B field in the so-called alpha = p(+) formulation. The string field theory in the infrared limit gives noncommutative gauge theory in the open string sector. Since this theory includes closed string fields as dynamical variables, we can obtain another string field theory in the same background through the condensation of closed string fields, whose low-energy effective action does not exhibit a noncommutativity of spacetime. Although we have two string field theories in the same background, we show that these theories are equivalent. In fact, we give the unitary transformation from string fields in one of them to string fields in the other., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, Dec. 2000, PROGRESS OF THEORETICAL PHYSICS, 104 (6), 1267 - 1287, doi;web_of_science

    Scientific journal

  • Open string field theory on noncommutative space

    T Kawano; T Takahashi

    We study Witten's open string field theory in the presence of a constant B field. We construct the string field theory in the operator formalism and find that, compared to the ordinary theory with no B field, the vertices in the resulting theory has an additional factor. This factor makes the zero modes of strings noncommutative. This is in agreement with the results in the first-quantized formulation. We also discuss the background independence of the purely cubic action derived from the above mentioned string field theory and then make a redefinition of string fields to remove the additional factor from the vertex. Furthermore, we briefly discuss the supersymmetric extension of our string field theory., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, Aug. 2000, PROGRESS OF THEORETICAL PHYSICS, 104 (2), 459 - 476, doi;web_of_science

    Scientific journal

  • One-loop tachyon amplitude in unoriented open-closed string field theory

    T Asakawa; T Kugo; T Takahashi

    We: calculate one-loop 2-point tachyon amplitudes in unoriented open-closed string field theory, and determine all the coupling constants of the interaction vertices in the theory. It is shown that the planar, nonplanar and nonorientable amplitudes are all reproduced correctly, and nontrivial consistencies among the determined coupling constants are observed. The necessity for the gauge group to be SO(2(13) = 8192) is also reconfirmed., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, Aug. 1999, PROGRESS OF THEORETICAL PHYSICS, 102 (2), 427 - 466, doi;web_of_science

    Scientific journal

  • BRS invariance of unoriented open-closed string field theory

    T Asakawa; T Kugo; T Takahashi

    We present the full action for the unoriented open-closed string held theory which is based on alpha = p(+) HIKKO type vertices. The BRS invariance of the action is proved up to terms which are expected to cancel the anomalous one-loop contributions. This implies that the system is invariant under the gauge transformations with open and closed string field parameters up to the anomalies., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, Oct. 1998, PROGRESS OF THEORETICAL PHYSICS, 100 (4), 831 - 879, doi;web_of_science

    Scientific journal

  • On the generalized gluing and resmoothing theorem

    T Asakawa; T Kugo; T Takahashi

    The generalized gluing and resmoothing theorem originally proved by LeClair, Peskin and Preitschopf gives a powerful formula for the fused vertex obtained by contracting any two vertices in string field theories. Although the theorem is naturally expected to hold for the vertices at any loop level, the original proof was restricted to the vertices at tree level. Here we present a simplified proof for the tree level theorem and then prove explicitly the extended version at the one-loop level., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, Aug. 1998, PROGRESS OF THEORETICAL PHYSICS, 100 (2), 437 - 454, doi;web_of_science

    Scientific journal

  • Unoriented open-closed string field theory

    T Kugo; T Takahashi

    The string field theory for an unoriented open-closed string mixed system is constructed up to quadratic order based on joining-splitting type vertices. The gauge invariance with a closed string transformation parameter is proved. The infinity cancellation mechanism between the disk and projective plane amplitudes plays an essential role for the gauge invariance of the theory., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, Apr. 1998, PROGRESS OF THEORETICAL PHYSICS, 99 (4), 649 - 689, doi;web_of_science

    Scientific journal

  • Duality of a supersymmetric model with the Pati-Salam group

    N Maekawa; T Takahashi

    Recently one of the authors proposed a dual theory of a Supersymmetric Standard Model (SSM), in which it is naturally understood that at least one quark (the top quark) should be heavy, i.e., almost the same order as the weak scale, and the supersymmetric Higgs mass parameter mu can naturally be expected to be small. However, this model cannot have Yukawa couplings of the lepton sector. In this paper, we examine a dual theory of a Supersymmetric Model with the Pati-Salam gauge group SU(4)(PS)xSU(2)(L)xSU(2)(R) with respect to the gauge group SU(4)(PS). In this scenario, Yukawa couplings of the lepton sector can be induced. In this model the Pati-Salam breaking scale should be around the SUSY breaking scale., KYOTO UNIV, Jun. 1996, PROGRESS OF THEORETICAL PHYSICS, 95 (6), 1167 - 1172, doi;web_of_science

    Scientific journal

  • Conformal anomaly of string theory in the harmonic gauge

    T Takahashi

    Considering the conformal anomaly in an effective action, the critical dimension of string theory can be determined in the harmonic gauge, in which it had been previously reported to be indefinite. In this gauge, there is no anomaly for the ghost number symmetry. This can be naturally understood in terms of the Faddeev-Popov conjugation in the theory., PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, May 1996, PROGRESS OF THEORETICAL PHYSICS, 95 (5), 995 - 1005, doi;web_of_science

    Scientific journal

  • POSSIBLE CANDIDATES FOR A SUPERSYMMETRIC SO(10) MODEL WITH AN INTERMEDIATE SCALE

    M BANDO; J SATO; T TAKAHASHI

    We study the possibility of an intermediate scale existing in supersymmetric SO(10) grand unified theories. The intermediate scale is required to be around 10(12) GeV so that neutrinos can obtain masses suitable for explaining the experimental data on the deficit of solar neutrinos with the Mikheyev-Smirnov-Wolfenstein solution and the existence of hot dark matter. We show that any Pati-Salam-type intermediate symmetries are excluded by requiring reasonable conditions and only SU(2)(L) x SU(2)(R) x SU(3)(G) x U(1)(B-L) is likely to be realized as an intermediate symmetry., AMERICAN PHYSICAL SOC, Sep. 1995, PHYSICAL REVIEW D, 52 (5), 3076 - 3080, doi;web_of_science

    Scientific journal

  • HIERARCHICAL MASS MATRICES IN A MINIMAL SO(10) GRAND UNIFICATION .2.

    M BANDO; KI IZAWA; T TAKAHASHI

    We continue to investigate the minimal SO(10) X U(1)(H) model which we proposed recently. Renormalization group analysis of the model results in natural predictions of quark-lepton masses and Kobayashi-Maskawa matrix along with neutrino mixings adequate for solar neutrino oscillation., KYOTO UNIV, Dec. 1994, PROGRESS OF THEORETICAL PHYSICS, 92 (6), 1137 - 1147, doi;web_of_science

    Scientific journal

  • HIERARCHICAL MASS MATRICES IN A MINIMAL SO(10) GRAND UNIFICATION .1.

    M BANDO; KI IZAWA; T TAKAHASHI

    We consider a minimal SO(10) unified model with horizontal Peccei-Quinn symmetry. The hierarchical structure of quark-lepton mass matrices is naturally implemented by the remnants of certain irrelevant terms. Georgi-Jarlskog relations are also realized due to the horizontal symmetry., KYOTO UNIV, Jul. 1994, PROGRESS OF THEORETICAL PHYSICS, 92 (1), 143 - 151, doi;web_of_science

    Scientific journal

  • Numerical twist-even SU(1,1)-singlet solutions in open string field theory around the identity-based solution

    Isao Kishimoto; Tomohiko Takahashi

    A<sc>bstract</sc> Using the level truncation method, we construct numerical solutions, which are twist even and SU(1) singlet, in the theory around the Takahashi-Tanimoto identity-based solution (TT solution) with a real parameter a in the framework of bosonic open string field theory. We find solutions corresponding to “double brane” and “ghost brane” solutions which were constructed by Kudrna and Schnabl in the conventional theory around the perturbative vacuum. Our solutions show somewhat similar a-dependence to tachyon vacuum and single brane solutions, which we found in the earlier works. In this sense, we might be able to expect that they are consistent with the conventional interpretation of a-dependence of the TT solution. We observe that numerical complex solutions at low levels become real ones at higher levels for some region of the parameter a. However, these real solutions do not so improve interpretation for double brane., Springer Science and Business Media LLC, Feb. 2021, Journal of High Energy Physics, 2021 (2), doi;url;url;rm:research_project_id

    Scientific journal

  • Reduction of open string amplitudes by mostly BRST exact operators

    Shigenori Seki; Tomohiko Takahashi

    Elsevier BV, Nov. 2021, Physics Letters B, 822, 136664 - 136664, doi

    Scientific journal

MISC

  • 星のスペクトルを通じた原子学習の実践と検討 -高等学校物理教育における高大連携授業研究の試み-

    米田隆恒; 高橋智彦

    Oct. 2017, 教育システム研究 別冊, 131 - 134

  • 三角形の五心を通じた図形学習の実践と検討 -高等学校数学教育における高大連携授業の試み-

    川口慎二; 高橋智彦

    Oct. 2017, 教育システム研究 別冊, 73 - 76

  • 定常磁場中の開弦と境界条件変更演算子

    高橋 智彦

    Mar. 2017, 奈良女子大学大学院研究交流支援プログラム 数学と物理学の研究交流シンポジウム報告書

  • Proceedings of the International Conference on String Field Theory and Related Aspects (SFT2010) October 18-22, 2010, Kyoto, Japan Preface

    Isao Kishimoto; Hiroshi Kunitomo; Tomohiko Takahashi

    PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, 2011, PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT, (188), I - I, web_of_science

    Others

  • 「標準理論」の宇宙; 現代物理の金字塔を楽しむ, B.A. シューム著, 森弘之訳, 日経BP 社

    高橋 智彦

    2010, 日本物理学会誌 (新著紹介), 65 (6)

    Book review

  • 弦の場の理論における厳密解

    高橋 智彦

    2008, 日本物理学会誌Vol. 63, No. 1, 2008 (最近の研究から)

  • 26aZA-4 Evaluation of gauge invariants for the Schnabl's solution

    Kawano Teruhiko; Kishimoto Isao; Kugo Taichiro; Takahashi Tomohiko

    一般社団法人 日本物理学会, 2008, Meeting Abstracts of the Physical Society of Japan, 63 (0), cinii_articles

  • 重力と量子化の問題~弦場と時空~

    高橋 智彦

    Dec. 2007, 数理科学2007 年12 月号, サイエンス社, (特集「時空」への問いかけ)

  • 弦の場の理論とその古典解

    高橋 智彦

    Feb. 2005, 立教大学SFR 自由研究プロジェクト研究 「弦理論と重力理論の数学的構造解明に関する学際的研究」 講究録, 4, 39

  • 弦の場の理論のゲージ構造

    高橋 智彦

    Mar. 2003, 奈良女子大学大学院研究交流支援プログラム 数学と物理学の研究交流シンポジウム報告書

  • Unoriented open-closed string field theory (vol 99, pg 649, 1998)

    T Kugo; T Takahashi

    PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, May 1999, PROGRESS OF THEORETICAL PHYSICS, 101 (5), 1187 - 1187, web_of_science

    Others

  • On the generalized gluing and resmoothing theorem (vol 100, pg 437, 1998)

    T Asakawa; T Kugo; T Takahashi

    PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE, May 1999, PROGRESS OF THEORETICAL PHYSICS, 101 (5), 1188 - 1188, web_of_science

    Others

Presentations

  • 4次元超対称非線形シグマ模型におけるコンペンセイター場とアノマリー

    近藤綾; 高橋智彦

    日本物理学会秋季大会, 16 Sep. 2020, 14 Sep. 2020, 17 Sep. 2020, rm:research_project_id

  • 開弦の場の理論における数値的「二重ブレーン」解の解析

    岸本功、高橋智彦

    日本物理学会第75回年次大会:現地開催中止, 18 Mar. 2020

  • Improved string amplitudes in operator formalism

    関穣慶; 高橋智彦

    日本物理学会第75回年次大会:現地開催中止, 17 Mar. 2020

  • アノマリーをもつ4次元超対称非線形シグマ模型の1/N展開による解析

    近藤綾、高橋智彦

    日本物理学会第75回年次大会:現地開催中止, 17 Mar. 2020

  • 4次元超対称非線形シグマ模型における有効ポテンシャルの解析

    近藤綾; 高橋智彦

    日本物理学会秋季大会(山形大学), 19 Sep. 2019

  • タキオン真空における世界面の構造について

    岸本功; 北出智巳; 関穣慶; 高橋智彦; 津田明日華

    日本物理学会秋季大会(山形大学), 19 Sep. 2019

  • タキオン真空とサイン二乗変形

    高橋 智彦

    理研研究会「サイン2乗変形(SSD)とその周辺2019」, 11 Jul. 2019

  • Closed string symmetries in open string field theory: tachyon vacuum as sine-square deformation

    Tomohiko TAKAHASHI

    International Conference on String Field Theory and String Perturbation Theory (SFT2019), 09 May 2019, Arcetri, Firenze, Italy

  • 超弦の場の理論におけるサイン二乗変形

    岸本功; 高橋智彦

    日本物理学会第74回年次大会(九州大学), 17 Mar. 2019

  • 超対称南部・Jona-Lasinio模型における質量項と超対称性の破れ

    近藤綾; 大木洋; 高橋智彦

    日本物理学会秋季大会(信州大学), 16 Sep. 2018

  • 開弦の場の理論における閉弦の対称性

    北出智巳; 岸本功; 高橋智彦

    日本物理学会秋季大会(信州大学), 15 Sep. 2018

  • 弦の場の理論におけるゲージ場の凝縮解とゲージ不変量

    高橋智彦; 石橋延幸; 岸本功; 増田暢

    日本物理学会第73回年次大会, 25 Mar. 2018

  • 超対称南部・Jona-Lasinio模型における隠れた局所対称性と量子異常

    近藤綾; 大木洋; 高橋智彦

    日本物理学会第73回年次大会, 25 Mar. 2018

  • 弦の場の理論におけるゲージ場の凝縮解とプロファイル

    高橋智彦; 石橋延幸; 岸本功; 増田暢

    日本物理学会秋季大会, 14 Sep. 2017

  • Vector profile of classical solutions for constant magnetic field background

    Tomohiko Takahashi

    SFT@HIT, 25 Jun. 2017

  • Erler-Maccaferri解について

    高橋智彦

    弦の場の理論16, 2016

  • 開弦の場の理論におけるディスク振幅について

    津川栞; 高橋智彦

    日本物理学会第71回年次大会, 2016

  • Classical solutions for gauge field condensation

    Tomohiko Takahashi

    String Field Theory and Related Aspects (SFT2016), 2016

  • 弦の場の理論におけるゲージ場の凝縮解

    高橋智彦; 石橋延幸; 岸本功

    日本物理学会秋季大会(宮崎大学木花キャンパス), 2016

  • String field theory solution corresponding to constant background magnetic field

    高橋智彦

    東北大学素粒子論研究室セミナー, 2016

  • 定常磁場中の開弦と境界条件変更演算子

    高橋智彦

    奈良女子大学 数学・物理・情報科学の研究交流シンポジウム, 2016

  • Multibrane Solutions and Chan-Paton Factors

    Tomohiko Takahashi

    String Field Theory and Related Aspects (SFT2015), 11 Mar. 2015

  • 多重ブレーン解とChan-Paton因子について

    竹本祥子; 岸本功; 増田暢; 高橋智彦

    日本物理学会第70回年次大会, 2015

  • Observables for identity-based tachyon vacuum solutions

    Tomohiko Takahashi

    String Field Theory and Related Aspects (SFT2014), 01 Aug. 2014

  • 単位超弦場に基づくマージナル変形解のオーバラップ

    岸本功; 高橋智彦; 増田暢

    日本物理学会第69回年次大会, 2014

  • 単位弦場に基づくタキオン真空解の物理量

    高橋智彦; 岸本功; 増田暢

    日本物理学会秋季大会, 2014

  • 単位弦場に基づくマージナル変形解周りの弦の場の理論の数値解

    岸本功; 高橋智彦

    日本物理学会第68回年次大会, 2013

  • マージナル変形された背景上の超弦の場の理論における古典解について

    岸本功; 高橋智彦

    日本物理学会第68回年次大会, 2013

  • マージナル変形された背景上でのオーバラップの解析

    岸本功; 高橋智彦

    日本物理学会秋季大会, 2013

  • 超弦の場の理論における単位弦場に基づく解とホモトピー演算子

    稲冨晶子; 岸本功; 高橋智彦

    日本物理学会第67回年次大会, 25 Mar. 2012

  • マージナル変形された背景上のタキオン真空解

    稲冨晶子; 岸本功; 高橋智彦

    日本物理学会秋季大会, 2012

  • Tachyon Vacuum in Marginally Deformed Backgrounds

    Tomohiko Takahashi

    String Field Theory and Related Aspects (SFT2012), 2012

  • Homotopy Operators and One-Loop Vacuum Energy at the Tachyon vacuum

    Tomohiko Takahashi

    String Field Theory and Related Aspects 2011, 20 Sep. 2011

  • タキオン真空における弦の場の理論の対称性について

    稲冨晶子; 高橋智彦

    日本物理学会第66回年次大会, 26 Mar. 2011

  • タキオン真空における開弦場のループ振幅

    稲冨晶子; 岸本功; 斉藤洋子; 高橋智彦

    日本物理学会第66回年次大会, 26 Mar. 2011

  • タキオン真空における1-ループ真空エネルギー

    日本物理学会秋季大会, 2011

  • A vacuum loop of an open string around an identity-based solution

    高橋 智彦

    String Field Theory and Related Aspects (SFT2010, Kyoto), 20 Oct. 2010

  • SFTにおける古典解まわりでの質量スペクトル

    高橋智彦; 稲冨晶子; 岸本功; 斉藤洋子

    日本物理学会秋季大会(九州工大戸畑キャンパス), 11 Sep. 2010

  • 単位弦場に基づく解のまわりの開弦の場の理論の数値解析

    高橋智彦; 岸本功

    21 Mar. 2010

  • 単位弦場に基づく解のまわりの開弦の場の理論の真空構造

    高橋智彦; 岸本功

    日本物理学会秋季大会(甲南大), 11 Sep. 2009

  • Exploring Vacuum Structure around Identity Based Solutions

    高橋 智彦

    String Field Theory and Related Aspects (SFT2009, Moscow), 13 Apr. 2009

  • 4次元超対称非線形シグマ模型と双対性について

    近藤綾; 関穣慶; 高橋智彦

    日本物理学会第76回年次大会, 14 Mar. 2021, 12 Mar. 2021, 15 Mar. 2021, rm:research_project_id

Association Memberships

  • 日本物理学会



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