TY - JOUR

T1 - 4 × 4-matrix transformation for systems with spontaneous symmetry breakdown and self-consistent renormalization in nonequilibrium Thermo Field Dynamics

AU - Oyama, T.

AU - Nakamura, Y.

AU - Yamanaka, Y.

N1 - Funding Information:
The authors thank KEK Theory Center for offering us the opportunity to discuss this work during the KEK Theory workshop on “Thermal Quantum Field Theories and Their Applications”, and Dr. R. Imai for the discussions conducted at an early stage of this study.
Publisher Copyright:
© 2021 The Authors

PY - 2022/4/1

Y1 - 2022/4/1

N2 - This study aims to construct a theoretical formulation of a nonequilibrium process for a system of Bose–Einstein condensate associated with a spontaneous symmetry breakdown. For this, Thermo Field Dynamics is used. We then describe the most general forms of a 4 × 4-matrix transformation and an unperturbed Hamiltonian. After calculating the 4 × 4-matrix self-energy and identifying its on-shell, we impose the renormalization condition in which the entire on-shell self-energy should vanish. This condition provides a sufficient number of independent equations to determine all of the parameters in an unperturbed Hamiltonian, among which the quantum transport equations for normal and anomalous number distributions are included.

AB - This study aims to construct a theoretical formulation of a nonequilibrium process for a system of Bose–Einstein condensate associated with a spontaneous symmetry breakdown. For this, Thermo Field Dynamics is used. We then describe the most general forms of a 4 × 4-matrix transformation and an unperturbed Hamiltonian. After calculating the 4 × 4-matrix self-energy and identifying its on-shell, we impose the renormalization condition in which the entire on-shell self-energy should vanish. This condition provides a sufficient number of independent equations to determine all of the parameters in an unperturbed Hamiltonian, among which the quantum transport equations for normal and anomalous number distributions are included.

KW - Nonequilibrium

KW - Quantum field theory

KW - Quantum transport equation

KW - Renormalization

KW - Thermo Field Dynamics

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U2 - 10.1016/j.physa.2021.126732

DO - 10.1016/j.physa.2021.126732

M3 - Article

AN - SCOPUS:85122201987

SN - 0378-4371

VL - 591

JO - Physica A: Statistical Mechanics and its Applications

JF - Physica A: Statistical Mechanics and its Applications

M1 - 126732

ER -