arXiv subjects

Hiroshi Kunitomo

Publications and source records attributed to Hiroshi Kunitomo.

At least 19 recordsLinked to original sources

arXiv2025

A consistent light-cone-gauge superstring field theory

Extending a recent development in the bosonic string field theory, we construct a map from the Witten-type gauge-invariant superstring field theory based on an $A_{\infty}$ structure to a light-cone-gauge superstring field theory via two intermediate theories, which we call the Kaku-type and Kugo-Zwiebach-type superstring field theories. We find that a naive extension only gives us an inconsistent light-cone-gauge theory that suffers from the well-known problem caused by divergence due to collisions of local operators. However, we also find that this difficulty may be resolved by considering the stubbed theory and propose it as a consistent light-cone-gauge superstring field theory. The result possibly gives a proof of the unitarity of the Witten-type superstring field theory.

hep-th↗

arXiv2022

Open-closed homotopy algebra in superstring field theory

We construct open-closed superstring interactions based on the open-closed homotopy algebra structure. It provides a classical open superstring field theory on general closed-superstring-field backgrounds described by classical solutions of the nonlinear equation of motion of the closed superstring field theory. We also give the corresponding WZW-like action through the map connecting the homotopy-based and WZW-like formulations.

hep-th↗

arXiv2021

Type II superstring field theory revisited

We reconstruct a complete type II superstring field theory with L-infinity structure in a symmetric way concerning the left- and right-moving sectors. Based on the new construction, we show again that the tree-level S-matrix agrees with that obtained using the first-quantization method. Not only is this a simple and elegant reconstruction, but it also enables the action to be mapped to that in the WZW-like superstring field theory, which has not yet been constructed and fills the only gap in the WZW-like formulation.

hep-th↗

arXiv2020

Tree-level S-matrix of superstring field theory with homotopy algebra structure

We show that the tree-level S-matrices of the superstring field theories based on the homotopy-algebra structure agree with those obtained in the first-quantized formulation. The proof is given in detail for the heterotic string field theory. The extensions to the type II and open superstring field theories are straightforward.

hep-th↗

arXiv2020

Type II superstring field theory with cyclic L-infinity structure

We construct a complete type II superstring field theory that includes all the NS-NS, R-NS, NS-R and R-R sectors. As in the open and heterotic superstring cases, the R-NS, NS-R and R-R string fields are constrained by using the picture-changing operators. In particular, we use a non-local inverse picture-changing operator for the constraint on the R-R string field, which seems to be inevitable due to the compatibility of the extra constraint with the closed string constraints. The natural symplectic form in the restricted Hilbert space gives a non-local kinetic action for the R-R sector, but it correctly provides the propagator expected from the first-quantized formulation. Extending the prescription previously obtained for the heterotic string field theory, we give a construction of general type II superstring products, which realizes a cyclic L-infinity structure, and thus provides a gauge-invariant action based on the homotopy algebraic formulation. Three typical four-string amplitudes derived from the constructed string field theory are demonstrated to agree with those in the first-quantized formulation. We also give the half-Wess-Zumino-Witten action defined in the medium Hilbert space whose left-moving sector is still restricted to the small Hilbert space.

hep-th↗

arXiv2019

Heterotic string field theory with cyclic L-infinity structure

We construct a complete heterotic string field theory that includes both the Neveu-Schwarz and Ramond sectors. We give a construction of general string products, which realizes a cyclic L-infinity structure and thus provides with a gauge-invariant action in the homotopy algebraic formulation. Through a map of the string fields, we also give the Wess-Zumino-Witten-like action in the large Hilbert space, and verify its gauge invariance independently.

hep-th↗

arXiv2017

Space-time supersymmetry in WZW-like open superstring field theory

We investigate space-time supersymmetry in the WZW-like open superstring field theory, whose complete action was recently constructed. Starting from a natural space-time supersymmetry transformation at the linearized level, we construct a nonlinear transformation so as to keep the complete action invariant. Then we show that the transformation satisfies the supersymmetry algebra up to an extra transformation, unphysical on the asymptotic string fields. This guarantees that the constructed transformation in fact acts as space-time supersymmetry on the physical S-matrix.

hep-th↗

arXiv2016

Construction of action for heterotic string field theory including the Ramond sector

Extending the formulation for open superstring field theory given in arXiv:1508.00366, we attempt to construct a complete action for heterotic string field theory. The action is non-polynomial in the Ramond string field Psi, and we construct it order by order in Psi. Using a dual formulation in which the role of eta and Q is exchanged, the action is explicitly obtained at the quadratic and quartic order in Psi with the gauge transformations.

hep-th↗

arXiv2016

Fermion scattering amplitudes from gauge-invariant actions for open superstring field theory

We calculate on-shell scattering amplitudes involving fermions at the tree level in open superstring field theory. We confirm that four-point and five-point amplitudes in the world-sheet path integral with the standard prescription using picture-changing operators are reproduced. For the four-point amplitudes, we find that the quartic interaction required by gauge invariance adjusts the different assignment of picture-changing operators in the $s$-channel and in the $t$-channel of Feynman diagrams with two cubic vertices. For the five-point amplitudes, the correct amplitudes are reproduced in a more intricate way via the quartic and quintic interactions. Our calculations can be interpreted as those for a complete action with a constraint on the Ramond sector or as those for the covariant formulation developed by Sen with spurious free fields.

hep-th↗

arXiv2016

Complete action for open superstring field theory

We construct a complete action for open superstring field theory that includes the Neveu-Schwarz sector and the Ramond sector. For the Neveu-Schwarz sector, we use the string field in the large Hilbert space of the superconformal ghost sector, and the action in the Neveu-Schwarz sector is the same as the Wess-Zumino-Witten-like action of the Berkovits formulation. For the Ramond sector, it is known that the BRST cohomology on an appropriate subspace of the small Hilbert space reproduces the correct spectrum, and we use the string field projected to this subspace. We show that the action is invariant under gauge transformations that are consistent with the projection for the string field in the Ramond sector.

hep-th↗

arXiv2015

Symmetries and Feynman Rules for Ramond Sector in Heterotic String Field Theory

Examining the symmetries of the pseudo-action, we propose a prescription for the new Feynman rules for the Ramond sector of the WZW-like heterotic string field theory. The new rules are an analog of that recently proposed for the open superstring field theory and respect all the gauge symmetries including those provided we impose the constraint after transformation. It is shown that the new rules reproduce the well-known on-shell tree-level amplitudes for four and five external strings including fermions.

hep-th↗

arXiv2015

Symmetries and Feynman Rules for Ramond Sector in Open Superstring Field Theory

We examine the symmetries of the action suppelemented by the constraint in the WZW-type open superstring field theory. It is found that this pseudo-action has additional symmetries provided we impose the constraint after the transformation. Respecting these additional symmetries, we propose a prescription for the new Feynman rules for the Ramond sector. It is shown that the new rules reproduce the well-known on-shell four- and five-point amplitudes with external fermions.

hep-th↗

arXiv2014

First-Order Equations of Motion for Heterotic String Field Theory

We consider the equations of motion of the full heterotic string field theory including both the Neveu-Schwarz and the Ramond sectors. It is shown that they can be formulated in the form of an infinite number of first-order equations for an infinite number of independent string fields. We prove that the conventional equations of motion are obtaned by solving the extra equations for the extra string fields with a certain assumptions at the linearized level. The conventional gauge transformations are also obtained from those in this first-order formulation, which is clarified by deriving some lower oder transformations explicitly.

hep-th↗

arXiv2014

The Ramond Sector of Heterotic String Field Theory

We attempt to construct the full equations of motion for the Neveu-Schwarz and the Ramond sectors of the heterotic string field theory. Although they are non-polynomial also in the Ramond string field $Ψ$, we can construct them order by order in $Ψ$. Their explicit forms with the gauge transformations are given up to the next-to-next-to-leading order in $Ψ$. We also determine a subset of the terms to all orders. By introducing an auxiliary Ramond string field $Ξ$, we construct a covariant action supplemented with a constraint, which should be imposed on the equations of motion. We propose the Feynman rules and show how they reproduce well-known physical four-point amplitudes with external fermions.

hep-th↗

arXiv2012

No-Ghost Theorem for Neveu-Schwarz String in 0-Picture

The no-ghost theorem for Neveu-Schwarz string is directly proved in 0-picture. The one-to-one correspondence between physical states in 0-picture and those in the conventional (-1)-picture are confirmed. It is shown that a non-trivial metric consistent with the BRST cohomology is needed to define a positive semi-definite norm in the physical Hilbert space. As a by-product, we find a new inverse picture changing operator, which is non-covariant but has non-singular operator product with itself. A possibility to construct a new gauge invariant superstring field theory is discussed.

hep-th↗

arXiv2012

Gauge Fixing of Modified Cubic Open Superstring Field Theory

The gauge-fixing problem of modified cubic open superstring field theory is discussed in detail both for the Ramond and Neveu-Schwarz sectors in the Batalin-Vilkovisky (BV) framework. We prove for the first time that the same form of action as the classical gauge-invariant one with the ghost-number constraint on the string field relaxed gives the master action satisfying the BV master equation. This is achieved by identifying independent component fields based on the analysis of the kernel structure of the inverse picture changing operator. The explicit gauge-fixing conditions for the component fields are discussed. In a kind of $b_0=0$ gauge, we explicitly obtain the NS propagator which has poles at the zeros of the Virasoro operator $L_0$.

hep-th↗

arXiv2009

Supersymmetric AdS_3 solutions in Heterotic Supergravity

We analyze the AdS_3 x M_7 type supersymmetric solutions, including non-trivial fluxes, of the Killing spinor equations in the heterotic supergravity. We classify these solutions by their G-structures and intrinsic torsions, for the cases that the number of seven-dimensional Killing spinors N are equal to 1,2,3 and 4. We find that the solutions cannot have non-trivial warp factor and the seven dimensional manifold M_7 is charactrized by G_2(SU(3))-structures for N=1 (2) case and SU(2)-structure for N=3 and 4 cases. They are further classified by their non-trivial intrinsic torsions. It is shown, including the leading order α'-corrections, that if we impose the Bianchi identities, the integrability conditions of the Killing spinor equations imply all the field equations.

hep-th↗

arXiv2008

Double-Spinor Superstrings on Coset Superspaces

The double-spinor formalism, proposed by Aisaka and Kazama, provides a basis for the pure-spinor formalism, which allows manifestly super-Poincare covariant quantization of superstrings. We extend it to the case of backgrounds realized by coset superspaces. A general method constructing reparametrization invariant action is given using two concrete examples, the flat space-time and AdS(5)xS(5). We find that it is natural to double not only the spinor coordinates but the whole superspace for describing double-spinor superstrings on such backgrounds. The reparametrization invariant action has local symmetries compensating those extra degrees of freedom, which guarantee the equivalence to the Green-Schwarz formalism.

hep-th↗