浅野 雅子

Abstract Covariant quantization of a multi-pronged open bosonic string junction is studied beyond static analysis. Its excited states are described by a set of ordinary bosons as well as some sets of twisted bosons on the worldsheet. The system is characterized by a certain large algebra of twisted type that includes a single Virasoro algebra as a subalgebra. By properly defining the physical states, one can show that there are no ghosts in the Hilbert space.

© 2016 We construct a class of quadratic gauge invariant actions for extended string fields defined on the tensor product of open superstring state space for multiple open string Neveu–Schwarz (NS) sectors with or without one Ramond (R) sector. The basic idea is the same as for the bosonic extended string field theory developed by the authors [1]. The theory for NSnsector and NSn−1–R sector contains general n-th rank tensor fields and (n−1)-th rank spinor–tensor fields in the massless spectrum respectively. In principle, consistent gauge invariant actions for any generic type of 10-dimensional massive or massless tensor or spinor–tensor fields can be extracted from the theory. We discuss some simple examples of bosonic and fermionic massless actions.

We propose a new gauge field theory which is an extension of ordinary string field theory by assembling multiple state spaces of the bosonic string. The theory includes higher-spin fields in its massless spectrum together with the infinite tower of massive fields. From the theory, we can easily extract the minimal gauge-invariant quadratic action for tensor fields with any symmetry. As examples, we explicitly derive the gauge-invariant actions for some simple mixed symmetric tensor fields. We also construct covariantly gauge-fixed action by extending the method developed for string field theory. © 2013 Elsevier B.V.

We propose a systematic procedure for extracting gauge invariant and gauge fixed actions for various higher-spin gauge field theories from covariant bosonic open string field theory. By identifying minimal gauge invariant part for the original free string field theory action, we explicitly construct a class of covariantly gauge fixed actions with BRST and anti-BRST invariance. By expanding the actions with respect to the level N of string states, the actions for various massive fields including higher-spin fields are systematically obtained. As illustrating examples, we explicitly investigate the level N <= 3 part and obtain the consistent actions for massive graviton field, massive 3rd rank symmetric tensor field, or anti-symmetric field. We also investigate the tensionless limit of the actions and explicitly derive the gauge invariant and gauge fixed actions for general rank n symmetric and anti-symmetric tensor fields. (c) 2012 Elsevier B.V. All rights reserved.

We show that a-gauge, a class of covariant gauges developed for bosonic open string field theory, is consistently applied to the closed string field theory. A covariantly gauge-fixed action of massless fields can be systematically derived from a-gauge-fixed action of string field theory.

A general class of gauges for open string field theory, for which the gauge fixing condition is given by linear equations with respect to string field, is investigated in detail. This class of gauges includes almost all known ones like Siegel gauge and its various extensions such as a-gauges proposed by the present authors as well as Schnabl gauge and linear b-gauges. A general form of propagators is determined and their common features are analyzed. A consistent procedure for calculating the amplitudes is given. Gauge independence of the on-shell physical amplitudes is explicitly shown. (C) 2008 Elsevier B.V. All rights reserved.

A single-parameter family of covariant gauge fixing conditions in bosonic string field theory is proposed. This is a natural string field counterpart to the covariant gauge in the conventional gauge theory, which includes the Landau gauge, as well as the Feynman (Siegel) gauge as special cases. The action in the Landau gauge is greatly simplified in such a manner that many of the component fields have no derivatives in their kinetic terms and appear in at most quadratic forms in the vertex.

New gauge fixing condition with single gauge parameter proposed by the authors is applied to the level truncated analysis of tachyon condensation in cubic open string field theory. It is found that the only one real non-trivial vacuum solution persists throughout the well-defined region of the gauge parameter, while the other solutions are turned out to be gauge-artifacts. Contrary to the previously known singular behavior in the Feynman-Siegel gauge, tachyon potential is remarkably smooth enough around Landau-type gauge.

We investigate the holographic correspondence between (p + 1)-dimensional (0 less than or equal to p less than or equal to 4) SYM theories with 16 supercharges and superstring theories on the near-horizon limit of Dp-brane backgrounds. We take an approach to holography based on the tunneling picture and study superstring with Euclidean world-sheet. We obtain the amplitude in a semi-classical approximation around a null geodesic which connects two-points on the boundary of the spacetime. As an extension of the analysis of hep-th/0308024, we study the fermionic sector of the superstring. For p not equal 3, we do not have world-sheet supersymmetry, and the energies of bosonic and fermionic fluctuations do not match. By interpreting the superstring amplitudes as correlators of gauge theory operators with large R-charge J, we obtain gauge theory two-point functions including those of fermionic operators. Our approach yields results consistent with the previous supergravity analysis for the D0-branes, including the subleading part in J. Our prediction from holography is that the two-point functions for the supergravity modes are power-law behaved, even for the non-conformal (p not equal 3) SYM theories. (C) 2004 Elsevier B.V. All rights reserved.

We re-examine physical state representations in the covariant quantization of bosonic string. We especially consider one parameter family of gauge fixing conditions for the residual gauge symmetry due to null states (or BRST exact states), and obtain explicit representations of observable Hilbert space which include those of the DDF states. This analysis is aimed at giving a necessary ingredient for the complete gauge fixing procedures of covariant string field theory such as temporal or light-cone gauge. © SISSA 2005.

It is well known that the standard no-ghost theorem is valid as long as the background has the light-cone directions. We prove the no-ghost theorem for the NSR string when only the timelike direction is flat. This is done by the BRST quantization, using the technique of Frenkel, Garland and Zuckerman and our previous results for the bosonic string. The theorem actually applies as long as the timelike direction is written as a u(1) SCFT. © 2003 Elsevier B.V. All rights reserved.

As an extension of the so-called BMN conjecture, we investigate the<br /> plane-wave limit for possible holographic connection between bulk string<br /> theories in non-conformal backgrounds of D$p$-branes and the corresponding<br /> supersymmetric gauge theories for $p&lt;5$. Our work is based on the tunneling<br /> picture for dominant null trajectories of strings in the limit of large angular<br /> momentum. The tunneling null trajectories start from the near-horizon boundary<br /> and return to the boundary, and the resulting backgrounds are time-dependent<br /> for general D$p$-branes except for $p=3$. We develop a general method for<br /> extracting diagonalized two-point functions for boundary theories as Euclidean<br /> (bulk) S-matrix in the time-dependent backgrounds. For the case of D0-brane,<br /> two-point functions of supergravity modes are shown to agree with the results<br /> derived previously by the perturbative analysis of supergravity. We then<br /> discuss the implications of the holography for general cases of D$p$-branes<br /> including the stringy excitations. All the cases ($p\ne 3, p&lt;5$) exhibit<br /> interesting infra-red behaviors, which are different from free-field theories,<br /> suggesting the existence of quite nontrivial fixed-points in dual gauge<br /> theories.

In our previous papers, we prove the no-ghost theorem without light-cone<br /> directions (hep-th/0005002, hep-th/0303051). We point out that our results are<br /> valid for more general backgrounds. In particular, we prove the no-ghost<br /> theorem for AdS_3 in the context of the BRST quantization (with the standard<br /> restriction on the spin). We compare our BRST proof with the OCQ proof and<br /> establish the BRST-OCQ equivalence for AdS_3. The key in both approaches lies<br /> in the certain structure of the matter Hilbert space as a product of two Verma<br /> modules. We also present the no-ghost theorem in the most gener...

We study one-loop effective action of Berkooz-Douglas matrix theory and obtain non-Abelian action of D0-branes in the longitudinal 5-brane background. In this paper, we extend the analysis of hep-th/0201248 and calculate the part of the effective action containing fermions. We show that the effective action is manifestly invariant under the loop-corrected SUSY transformation, and give the explicit transformation laws. The effective action consists of blocks which are closed under the SUSY, and it includes the supersymmetric completion of the couplings to the longitudinal 5-branes proposed by Taylor and Van Raamsdonk as a subset. (C) 2002 Elsevier Science B.V. All rights reserved.

We study one-loop effective action of Berkooz-Douglas Matrix theory and obtain non-abelian action of DO-branes in the background field produced by longitudinal 5-branes Since these 5-branes do not have D0-brane charge and are not present in BFSS Matrix theory, Our analysis provides an independent test for the coupling of D-branes to general weak backgrounds proposed by Taylor and Van Raamsdonk from the analysis of the BFSS model. The proposed couplings appear in the Berkooz-Douglas effective action precisely as expected, which suggests the consistency of the two matrix models. We also point out the existence of the terms which are not given by the symmetrized trace prescription in the Matrix theory effective action. (C) 2002 Elsevier Science B.V All rights reserved.

It is well-known that the standard no-ghost theorem can be extended straightforwardly to the general c=26 CFT on Rd-1,1×K , where 2≤d≤26 and K is a compact unitary CFT of appropriate central charge. We prove the no-ghost theorem for d=1 , i.e., when only the timelike direction is flat. This is done using the technique of Frenkel, Garland and Zuckerman. © 2000 Elsevier Science B.V.