Light-cone Gauge String Field Theory Research Articles

Causality in string field theory

In this letter, we will investigate causality in string field theory using pp-wave light-cone gauge string field theory. We will generalise the Ramsey scheme to string field theory, and use it to analyze string field theoretical processes. An explicit characteristic function for interactive string field theory will be built using this string field theoretical Ramsey scheme. The average of the difference between the initial and final values of any operator described in string field theory will be obtained using this characteristic function. We will use the quantum information theoretical technique based on quantum Fisher information to extract information about such string field theoretical processes.

Worldsheet theory of light-cone gauge noncritical strings on higher genus Riemann surfaces

It is possible to formulate light-cone gauge string field theory in noncritical dimensions. Such a theory corresponds to conformal gauge worldsheet theory with nonstandard longitudinal part. We study the longitudinal part of the worldsheet theory on higher genus Riemann surfaces. The results in this paper shall be used to study the dimensional regularization of light-cone gauge string field theory.

Light-Cone Gauge String Field Theory and Dimensional Regularization

We review our recent proposals to dimensionally regularize the light-cone gauge string field theory.

Amplitudes in Noncritical Dimensions and Dimensional Regularization

We study how the dimensional regularization works in the light-cone gauge string field theory. We show that it is not necessary to add a contact term to the string field theory action as a counter term in this regularization at least at the tree level. We also investigate the one-loop amplitudes of the bosonic theory in noncritical dimensions and show that they are modular invariant.

Light-cone gauge NSR strings in noncritical dimensions II — Ramond sector

Light-cone gauge superstring theory in noncritical dimensions corresponds to a worldsheet theory with nonstandard longitudinal part in the conformal gauge. The longitudinal part of the worldsheet theory is a superconformal field theory called X^{\pm} CFT. We show that the X^{\pm} CFT combined with the super-reparametrization ghost system can be described by free variables. It is possible to express the correlation functions in terms of these free variables. Bosonizing the free variables, we construct the spin fields and BRST invariant vertex operators for the Ramond sector in the conformal gauge formulation. By using these vertex operators, we can rewrite the tree amplitudes of the noncritical light-cone gauge string field theory, with external lines in the (R,R) sector as well as those in the (NS,NS) sector, in a BRST invariant way.

Light-cone gauge string field theory in noncritical dimensions

We study light-cone gauge string field theory in noncritical space-time dimensions. Such a theory corresponds to a string theory in a Lorentz noninvariant background. We identify the worldsheet theory for the longitudinal coordinate variables X± and study its properties. It is a CFT with the right value of Virasoro central charge, using which we propose a BRST invariant formulation of the worldsheet theory.

Observables and correlation functions inOSpinvariant string field theory

We define BRST invariant observables in the OSp invariant closed string field theory for bosonic strings. We evaluate correlation functions of these observables and show that the S-matrix elements derived from them coincide with those of the light-cone gauge string field theory.

Causality in covariant string field theory

Causality is studied in the covariant formulation of free string field theory (SFT). We find that, though the string field in the covariant formulation is a functional of the ghost coordinates as well as the space-time coordinate and the latter contains the time-like oscillators with negative norm, the condition for the commutator of two open string fields to vanish is simply given by ∫ O τ dδ(ΔX μ(δ)) 2<O , which is the same condition as in the light-cone gauge SFT. For closed SFT, the corresponding condition is given in a form which is manifestly invariant under the rigid shifts of the σ parameters of the two string fields.

Temporal-gauge string field with open strings

A string field theory including open string fields is constructed in the temporal gauge. It consists of string interaction vertices similar to the light-cone gauge string field theory. A slight modification of the definition of the time coordinate is needed because of the existence of the open string end points.

Vacuum values for auxiliary string fields

Auxiliary string fields are introduced in light-cone gauge string field theory in order to express contact interactions as contractions of cubic vertices. The auxiliary field in the purely closed-string bosonic theory may be given a non-zero expectation value, giving rise to a phase in which world-sheets have boundaries.

Dilaton Condensation in the Covariantized Light-Cone Closed String Field Theory

We analyze dilaton condensation in the covariantized light·cone closed string field theory. We show by explicit calculation that an infinitesimal condensation of the dilaton field gives rise to the shift of the string coupling constant 9 by an amount (Jg= -(Cd -2)/2)g, where d is the space-time dimension. This agrees with Yoneya's result obtained in the light-cone gauge string field theory. We also show that the direct effect of the dilaton condensation is interpreted as the Weyl-scaling of the full OSP(d -1,112) metric including the ghost direction also.

Quantization of non-local field theory and string field theory

The interaction vertex in covariant string field theory (SFT) is non-local in the time coordinate and the conventional canonical quantization is inapplicable to it. As an approach to quantizing this system we apply Hayashi's theory of the Hamilton formalism for field theories with non-local interactions. We find that the resulting one-loop amplitudes in covariant closed SFT coincide with those in the light-cone gauge SFT.

Equivalence of the scattering amplitudes of the light-cone gauge and the Osp (26,2|2) invariant string field theories

It is shown that at all orders of perturbation the scattering amplitudes of the Osp(26,2|2) invariant bosonic string field theory of Neveu and West are equal to the ones which result from the light-cone gauge string field theory.