Details of the Researcher

PHOTO

Hiroshi Ishikawa
Section
Graduate School of Science
Job title
Associate Professor
Degree

  • 博士(理学) (The University of Tokyo)

Committee Memberships 2

  • 日本物理学会 物理教育委員会　委員

    2013/04 - 2016/03

  • 日本物理学会 物理教育委員会　委員

    2013/04 - 2016/03

Professional Memberships 1

  • 日本物理学会

Research Interests 2

  • conformal field theory

  • string theory

Research Areas 1

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

Papers 13

  1. Twisted boundary states and representation of generalized fusion algebra Peer-reviewed

    H Ishikawa, T Tani

    NUCLEAR PHYSICS B　739　(3)　328-388　2006/04

    DOI： 10.1016/j.nuclphysb.2006.01.031 　

    ISSN： 0550-3213

  2. Twisted boundary states in Kazama-Suzuki models Peer-reviewed

    H Ishikawa, T Tani

    NUCLEAR PHYSICS B　678　(1-2)　363-397　2004/02

    DOI： 10.1016/j.nuclphysb.2003.11.011 　

    ISSN： 0550-3213

  3. Twisted boundary states in c=1 coset conformal field theories Peer-reviewed

    H Ishikawa, A Yamaguchi

    JOURNAL OF HIGH ENERGY PHYSICS　03　(4)　26　2003/04

    ISSN： 1029-8479

  4. Novel construction of boundary states in coset conformal field theories Peer-reviewed

    H Ishikawa, T Tani

    NUCLEAR PHYSICS B　649　(1-2)　205-242　2003/01

    DOI： 10.1016/S0550-3213(02)01011-8 　

    ISSN： 0550-3213

  5. Boundary states in coset conformal field theories Peer-reviewed

    H Ishikawa

    NUCLEAR PHYSICS B　629　(1-3)　209-232　2002/05

    DOI： 10.1016/S0550-3213(02)00131-1 　

    ISSN： 0550-3213

  6. Free field realization of D-brane in group manifold Peer-reviewed

    H Ishikawa, S Watamura

    JOURNAL OF HIGH ENERGY PHYSICS　0008　(8)　2000/08

    ISSN： 1029-8479

  7. BPS mass spectrum from D-brane action Peer-reviewed

    H Ishikawa, Y Matsuo, Y Sugawara, K Sugiyama

    PHYSICS LETTERS B　388　(2)　296-302　1996/11

    DOI： 10.1016/S0370-2693(96)01262-2 　

    ISSN： 0370-2693

  8. On the equivalence of fermionic string to bosonic string in two dimensions Peer-reviewed

    H Ishikawa

    PHYSICS LETTERS B　385　(1-4)　117-124　1996/09

    DOI： 10.1016/0370-2693(96)00850-7 　

    ISSN： 0370-2693

  9. Non-linear structures in the non-critical NSR string Peer-reviewed

    KJ Hamada, H Ishikawa

    COMMUNICATIONS IN MATHEMATICAL PHYSICS　176　(2)　401-420　1996/03

    DOI： 10.1007/BF02099555 　

    ISSN： 0010-3616

  10. C=1 STRING AS A TOPOLOGICAL MODEL Peer-reviewed

    H ISHIKAWA, M KATO

    INTERNATIONAL JOURNAL OF MODERN PHYSICS A　9　(32)　5769-5789　1994/12

    DOI： 10.1142/S0217751X94002387 　

    ISSN： 0217-751X

  11. TOPOLOGICAL-STRUCTURE IN C=1 FERMIONIC STRING THEORY Peer-reviewed

    S HIRANO, H ISHIKAWA

    MODERN PHYSICS LETTERS A　9　(33)　3077-3087　1994/10

    DOI： 10.1142/S0217732394002902 　

    ISSN： 0217-7323

  12. NOTE ON N = 0 STRING AS N = 1 STRING Peer-reviewed

    H ISHIKAWA, M KATO

    MODERN PHYSICS LETTERS A　9　(8)　725-728　1994/03

    DOI： 10.1142/S0217732394000538 　

    ISSN： 0217-7323

  13. EQUIVALENCE OF BRST COHOMOLOGIES FOR THE 2D BLACK-HOLE AND C = 1 LIOUVILLE THEORY Peer-reviewed

    H ISHIKAWA, M KATO

    PHYSICS LETTERS B　302　(2-3)　209-214　1993/03

    DOI： 10.1016/0370-2693(93)90386-V 　

    ISSN： 0370-2693

Show all ︎Show first 5

Misc. 2

  1. Mechanics Class Designed for Students Who have not Studied Physics

    7　419-424　2021/03

    Publisher: 東北大学高度教養教育・学生支援機構

    ISSN： 2434-8317

  2. 全学教育科目物理学Dにおける補習連携型授業の導入について - 初年度学習支援の一つの試み -

    石川 洋

    東北大学高等教育開発推進センター紀要　(3)　267-275　2008/03

    Publisher: 東北大学高等教育開発推進センター

    ISSN： 1881-0853

Books and Other Publications 2

  1. 力学入門

    石川, 洋

    東北大学出版会　2019/03

    ISBN: 9784861633263

  2. はじめての物理数学

    石川 洋

    東北大学出版会　2010/03

Research Projects 5

  1. Phenomenological and cosmological studies towards building new paradigm of particle hysics

    YAMAGUCHI Masahiro, HIKASA Kenichi, ISHIKAWA Hiroshi, YOKOYAMA Junichi, TANABASHI Masaharu, MOROI Takeo

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (B)

    Institution: Tohoku University

    2005 - 2008

  2. D-braneによる共形場理論の幾何学的解釈

    石川 洋

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 若手研究(B)

    Institution: 東北大学

    2003 - 2004

    More details Close

    この研究の第一の目的は、幾何学的な解釈が明らかではない共形場理論(Conformal Field Theory, CFT)について、点(D0-brane)を同定する基準を明確にすることである。そのためには、まず、一般のCFTにおいて、どのようなD-braneが存在するのかを分類する必要がある。 D-braneとは共形不変な境界条件である。多くのCFTでは共形対称性を含むより高い対称性(カイラル代数)がある。カイラル代数がある場合のD-braneの重要なクラスとして、カイラル代数を部分的に破るようなD-braneがある。カイラル代数の同型ωがヴィラソロ代数を不変に保つ場合、ωで境界条件をひねることにより、このようなD-braneを構成することができる。今年度の研究では、このようなカイラル代数の同型に由来するD-braneの構造を調べ、以下の事実を明らかにした: ・カイラル代数の同型ωに対応して、CFTのフュージョン代数をωで拡大した代数(一般化されたフュージョン代数)が存在する。 ・一般化されたフュージョン代数は、一般に非可換である。 ・同型ωでひねった境界条件をみたすD-braneは、一般化されたフュージョン代数の表現をなす。 これらの結果は、カイラル代数をすべて保つD-braneの場合について知られていた結果(カイラル代数をすべて保つD-braneは、フュージョン代数の表現となる)を一般化したものになっている。特に、フュージョン代数の非可換な拡大は今まで知られていなかったものである。 これらの結果については、現在、論文を準備中である ("Twisted boundary states and representation of generalized fusion algebras",in preparation)。

  3. Research on the Field Theory in the Noncommutative Space obtained through the Deformation Quantization and its Application

    WATAMURA Satoshi, ISHIKAWA Hiroshi

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (C)

    Institution: Tohoku University

    2001 - 2004

    More details Close

    In the string theory it becomes very important to understand the field theory on the noncommutative geometry, since it appears as an effective theory of the D-brane. The essence of the field theory over the noncommutative geometry is considered to appear in the curved space. However, unlike the analysis of the instanton solution over (flat) four-dimensional Euclidian space, the study of the theory on the curved noncommutative space is not so well understood. One origin of this is the lack of typical examples. Our previous research about the fuzzy sphere gives many interesting aspects from various points of view : It appears as a D-brane configuration in string theory. However, it is also interesting as a regularized theory since it has a chiral fermion structure similar to the lattice case. It is therefore important to find more examples. In our recent investigation, we have constructed noncommutative CPn by generalizing the fuzzy sphere. The line bundle was constructed in terms of projective modules and we analyzed its topological structure. The differential calculus is defined in a similar way as in the fuzzy sphere case and the noncommutative analogue of the Chern character of the noncommutative CPn is given. In this context it is necessary to understand the meaning of the subsphere in order to perform the integration. It turns out that a certain class of subsphere remains as a subsphere in the commutative limit, and in this case we can evaluate the first Chern number. (Published as hep-th 0404130.)

  4. The construction of the field theory on the noncommutative spaces and its application

    WATAMURA Satoshi, ISHIKAWA Hiroshi

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (C)

    Institution: TOHOKU UNIVERSITY

    1997 - 2000

    More details Close

    The aim of this research is to construct the field theory over the non-commutative space and to analyze its physical properties. In the last 4 years research supported by the present Grant-in-Aid we have been especially investigating the field theory on the non-commutative sphere as a concrete example of a non-commutative curved space. The non-commutative sphere is defined by quantizing the algebra over the 2-sphere. As a first step in this direction we have constructed the non-commutative differential algebra according to the approach given by Connes (paper 1), and as its application we formulated the scalar field on the non-commutative sphere (paper 2). Our main interest is to define the gauge theory on the non-commutative sphere. However, for this end we had to analyze further detailed structure of the differential calculus. In paper 3 we succeeded to formulated the U (1) gauge theory, and we have analyzed its commutative limit. Especially in gauge theory we obtained a new term and the structure of this new term, which does not have a correspondence in the commutative case, gives us a tool to classify the gauge theory on the non-commutative sphere. Recently, it is found that the D-brane which wraps around the torus possesses a non-commutative structure in the background of an antisymmetric tensor field. It is an interesting problem to investigate the ralation between string theory and non-commutative geometry. From this point of view we investigated the D-brane in the group manifold and constructed the boundary state in the SU (2) manifold (paper 5). The effective theory of this D-brane in SU (2) is given by the gauge thoery on the non-commutative sphere described above and we are presently researching those relations.

  5. Non-perturbative Aspects of Super string Theory Competitive

    System: Basic Science Research Program

    1996/09 -