Thermal $D$-Brane Boundary States from Green-Schwarz Superstrings

TL;DR

This paper thermalizes type II superstrings using the TFD formalism, deriving thermal boundary states from BPS D-branes, and analyzes supersymmetry breaking, partition function, and entropy at finite temperature.

Contribution

It introduces a method to obtain thermal D-brane boundary states from zero-temperature BPS D-branes within the TFD framework for superstrings.

Findings

Thermal boundary states are derived from BPS D-branes.

Supersymmetry is partially broken, with specific transformations preserved.

Thermal partition function and entropy are computed for the thermal string.

Abstract

In this paper we thermalize the type II superstrings in the GS formulation by applying the TFD formalism. The thermal boundary conditions on the thermal Hilbert space are obtained from the BPS $D$-brane boundary conditions at zero temperature. We show that thermal boundary states can be obtained by thermalization from the BPS $D$-branes at zero temperature. These new states can be interpreted as thermal $D$-branes. Next, we discuss the supersymmetry breaking of the thermal string in the TFD approach. We identify the broken supersymmetry with the $\epsilon$-transformation while the $\eta$-transformation is preserved. Also, we compute the thermal partition function and the entropy of the thermal string.