Quantum Measurements in a Finite Space–Time Domain

In this paper, we discuss the quantum Unruh–DeWitt detector, which couples to the field bath for a finite amount of its proper time. It is demonstrated that due to the renormalization procedure, a new dimensionful parameter appears, having the meaning of a detector’s recovery proper time. It plays no role in the leading order of the perturbation theory, but can be important non-perturbatively. We also analyze the structure of finite time corrections in two cases—perturbative switching on, and switching off when the detector is thermalized.

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NAMBU-JONA-LASINIO MODEL IN CURVED SPACE-TIME

Modern Physics Letters A ◽

10.1142/s0217732393001835 ◽

1993 ◽

Vol 08 (22) ◽

pp. 2117-2123 ◽

Cited By ~ 44

Author(s):

T. INAGAKI ◽

T. MUTA ◽

S.D. ODINTSOV

Keyword(s):

Proper Time ◽

Space Time ◽

Leading Order ◽

Coupling Constant ◽

Normal Coordinate ◽

Dynamical Mass ◽

Curved Space ◽

First Order ◽

First Order Phase Transition ◽

First Order Phase

The phase structure of Nambu-Jona-Lasinio model with N-component fermions in curved space-time is studied in the leading order of the 1/N expansion. The effective potential for composite operator [Formula: see text] is calculated by using the normal coordinate expansion in the Schwinger proper-time method. The existence of the first order phase transition caused by the change of the space-time curvature is confirmed and the dynamical mass of the fermion is calculated as a simultaneous function of the curvature and the four-fermion coupling constant. The phase diagram in the curvature and the coupling constant is obtained.

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A kinetic equation for unstable plasmas in a finite space-time domain

Physics of Plasmas ◽

10.1063/1.2979689 ◽

2008 ◽

Vol 15 (9) ◽

pp. 092111 ◽

Cited By ~ 15

Author(s):

S. D. Baalrud ◽

J. D. Callen ◽

C. C. Hegna

Keyword(s):

Kinetic Equation ◽

Time Domain ◽

Space Time ◽

Finite Space

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Vacuum thermal effects in flat space-time from conformal quantum mechanics

Journal of High Energy Physics ◽

10.1007/jhep07(2021)003 ◽

2021 ◽

Vol 2021 (7) ◽

Author(s):

Michele Arzano

Keyword(s):

Quantum Mechanics ◽

Minkowski Space ◽

Time Evolution ◽

Time Domain ◽

Thermal Effects ◽

Proper Time ◽

Space Time ◽

Theoretical Derivation ◽

Minkowski Space Time ◽

Conformal Quantum Mechanics

Abstract The generators of radial conformal symmetries in Minkowski space-time can be mapped to the generators of time evolution in conformal quantum mechanics. Within this correspondence we show that in conformal quantum mechanics the state associated to the inertial vacuum in Minkowski space-time has the structure of a thermofield double. Such state is built from a bipartite “vacuum state”, the ground state of the generators of hyperbolic time evolution, which cover only part of the time domain. When time evolution is restricted to a finite time domain one obtains the temperature perceived by static diamond observers in the Minkowski vacuum. When time evolution is determined by dilations, covering only half of the time line, the temperature of the thermofield double corresponds to the non-vanishing temperature perceived by Milne observers whose proper time evolution is confined to the future cone (Milne universe) of Minkowski space-time. The two pictures are related by a conformal transformation on the real line. Our result provides a purely group theoretical derivation of the Milne and diamond temperatures and shows that the fundamental ingredient for vacuum thermal effects is the presence of a horizon rather than acceleration.

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Modeling Transient Flows in Heterogeneous Layered Porous Media Using the Space–Time Trefftz Method

Applied Sciences ◽

10.3390/app11083421 ◽

2021 ◽

Vol 11 (8) ◽

pp. 3421

Author(s):

Cheng-Yu Ku ◽

Li-Dan Hong ◽

Chih-Yu Liu ◽

Jing-En Xiao ◽

Wei-Po Huang

Keyword(s):

Porous Media ◽

Time Domain ◽

Numerical Solutions ◽

Space Time ◽

Two Dimensional ◽

Transient Flows ◽

Layered Porous Media ◽

Time Marching ◽

Time Basis ◽

Marching Scheme

In this study, we developed a novel boundary-type meshless approach for dealing with two-dimensional transient flows in heterogeneous layered porous media. The novelty of the proposed method is that we derived the Trefftz space–time basis function for the two-dimensional diffusion equation in layered porous media in the space–time domain. The continuity conditions at the interface of the subdomains were satisfied in terms of the domain decomposition method. Numerical solutions were approximated based on the superposition principle utilizing the space–time basis functions of the governing equation. Using the space–time collocation scheme, the numerical solutions of the problem were solved with boundary and initial data assigned on the space–time boundaries, which combined spatial and temporal discretizations in the space–time manifold. Accordingly, the transient flows through the heterogeneous layered porous media in the space–time domain could be solved without using a time-marching scheme. Numerical examples and a convergence analysis were carried out to validate the accuracy and the stability of the method. The results illustrate that an excellent agreement with the analytical solution was obtained. Additionally, the proposed method was relatively simple because we only needed to deal with the boundary data, even for the problems in the heterogeneous layered porous media. Finally, when compared with the conventional time-marching scheme, highly accurate solutions were obtained and the error accumulation from the time-marching scheme was avoided.

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Single-shot measurement of the free-space time domain terahertz (THz) waveforms by iterative frequency-domain interferometry technology

Optical and Quantum Electronics ◽

10.1007/s11082-019-2039-x ◽

2019 ◽

Vol 51 (10) ◽

Cited By ~ 1

Author(s):

Yupeng Fan ◽

Junjun Xiao ◽

Yi Li

Keyword(s):

Frequency Domain ◽

Time Domain ◽

Free Space ◽

Space Time ◽

Single Shot

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Strong CP violation in spin-1/2 singly charmed baryons

Journal of High Energy Physics ◽

10.1007/jhep01(2021)115 ◽

2021 ◽

Vol 2021 (1) ◽

Author(s):

Y. Ünal ◽

Ulf-G. Meißner

Keyword(s):

Perturbation Theory ◽

Dipole Moment ◽

Form Factor ◽

Cp Violation ◽

Mass Shell ◽

Chiral Expansion ◽

Renormalization Scheme ◽

Leading Order ◽

Chiral Perturbation ◽

Charmed Baryons

Abstract We report on the calculation of the CP-violating form factor F3 and the corresponding electric dipole moment for charmed baryons in the spin-1/2 sector generated by the QCD θ-term. We work in the framework of covariant baryon chiral perturbation theory within the extended-on-mass-shell renormalization scheme up to next-to-leading order in the chiral expansion.

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