Related papers: On the SU(1,1) Thermal Group of Bosonic Strings an…
The Thermo Field Dynamics formalism is presented. In particular, it is applied to the two-dimensional field theory that describes a open bosonic string. The value of entropy operator is computed in various Dirichlet and Neumann boundary…
A generalization of the Thermo Field Dynamics (TFD) for fermionic degrees of freedom is proposed. Such a generalization follows a previous one where the SU(1,1) thermal group was used to obtain the closed bosonic string at finite…
In this paper we review the construction of the thermal bosonic string and $D$-brane in the framework of the Thermo Field Dynamics (TFD). We briefly recall the well-known light-cone quantization of the bosonic string in the conformal gauge…
In this work we explain the construction of the thermal vacuum for the bosonic string, as well that of the thermal boundary state interpreted as a $D_{p}$-brane at finite temperature. In both case we calculate the respective entropy using…
In this letter, an entropy operator for the general unitary SU(1,1) TFD formulation is proposed and used to lead a bosonic system from zero to finite temperature. Namely, considering the closed bosonic string as the target system, the…
In this work we discuss a generalization for the thermal Bogoliubov transformation in the context of a hermitian general SU(1,1) transformation generator. The TFD tilde conjugation rules are redefined using an appropriated Tomita-Takesaki…
We construct the D-brane states at finite temperature in thermal equilibrium in the $\mathbb{R}^{1,p}\times{\mathbb{T}}^{d-p-1}$ spacetime in the presence of cold (unthermalized) Kalb-Ramond (KR) and U(1) gauge potential background. To this…
Bosonic boundary states at finite temperature are constructed as solutions of boundary conditions at $T\neq 0$ for bosonic open strings with a constant gauge field $F_{ab}$ coupled to the boundary. The construction is done in the framework…
Considering the type IIB superstring in a pp wave background some recent ideas and perspectives of Thermo Field Dynamics on string theory are presented. The thermal Fock space is constructed attempting to consider a possible finite…
We formulate the finite temperature theory for the free thermal excitations of the bosonic string in the anti-de Sitter (AdS) spacetime in the Thermo Field Dynamics (TFD) approach. The spacetime metric is treated exactly while the string…
In this Letter a topological interpretation for the string thermal vacuum in the Thermo Field Dynamics (TFD) approach is given. As a consequence, the relationship between the Imaginary Time and TFD formalisms is achieved when both are used…
We determine the local entropy of the free energy of the quantized open bosonic string in Minkowski spacetime with the most general boundary conditions. We formulate a finite temperature theory of the thermal closed string excitations in…
We show that bosonic D-brane states may be represented as coherent states in an open string representation. By using the Thermo-Field Dynamics (TFD) formalism, we may construct a condensed state of open string modes which encodes the…
The algebraic structure of Thermo Field Dynamics lies in the $q$-deformation of the algebra of creation and annihilation operators. Doubling of the degrees of freedom, tilde-conjugation rules, and Bogoliubov transformation for bosons and…
The Bogoliubov transformation in thermofield dynamics, an operator formalism for the finite-temperature quantum-field theory, is generalized to describe a field in arbitrary confined regions of space and time. Starting with the scalar…
The description of string-theoretic s-branes at g_s=0 as exact worldsheet CFTs with a (lambda cosh X^0) or (lambda e^(X^0)) boundary interaction is considered. Due to the imaginary-time periodicity of the interaction under X^0 -> X^0 + 2 pi…
A universal symmetric truncation of the bosonic string Hilbert space yields all known closed fermionic string theories in ten dimensions, their D-branes and their open descendants. We highlight the crucial role played by group theory and…
We construct the thermal boundary states from the type IIB Green-Schwarz superstring in {\em pp}-wave background in the light-cone gauge. The superstring is treated in the canonical ensemble and in the TFD formalism which is appropriate to…
Thermal Bogoliubov transformation is an essential ingredient of the thermo field dynamics -- the real time formalism in quantum field and many-body theories at finite temperatures developed by H. Umezawa and coworkers. The approach to study…
The thermofield dynamics of the D=26 closed bosonic thermal string theory is described in proper reference to the thermal duality symmetry as well as the thermal stability of modular invariance in association with the global phase structure…