Functional density matrix formulation of quantum statistics

Bessa, A.; Carvalho, C. A. A. de; Fraga, Eduardo S.

doi:10.1103/physreve.81.011103

Cited by 5 publications

(8 citation statements)

References 26 publications

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“…The integrand in the first term of the right hand side of ( 16) vanishes identically because φ c (x) obeys (13). The second term -a boundary term -vanishes due to the property (14) of the fluctuation η.…”

Section: Fluctuations At Fixed Boundarymentioning

confidence: 99%

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Quantum statistical correlations in thermal field theories: Boundary effective theory

et al. 2010

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We show that the one-loop effective action at finite temperature for a scalar field with quartic interaction has the same renormalized expression as at zero temperature if written in terms of a certain classical field φc, and if we trade free propagators at zero temperature for their finitetemperature counterparts. The result follows if we write the partition function as an integral over field eigenstates (boundary fields) of the density matrix element in the functional Schrödinger fieldrepresentation, and perform a semiclassical expansion in two steps: first, we integrate around the saddle-point for fixed boundary fields, which is the classical field φc, a functional of the boundary fields; then, we perform a saddle-point integration over the boundary fields, whose correlations characterize the thermal properties of the system. This procedure provides a dimensionally-reduced effective theory for the thermal system. We calculate the two-point correlation as an example. * abessa@ect.ufrn.br †

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Section: Fluctuations At Fixed Boundarymentioning

confidence: 99%

“…By construction, φ c [φ 0 ] satisfies the equation of motion (13), so that the first term on the r.h.s. of (32) vanishes.…”

Section: Fluctuating the Boundary Fieldmentioning

confidence: 99%

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Quantum statistical correlations in thermal field theories: Boundary effective theory

et al. 2010

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“…1. For comparison, we also use the bag model for the quark phase in our calculations and discussion, choosing the bag constant according to the critical temperature obtained by the crossing of the pressure curves [39]. Finally, the relations (6) leave two remaining conditions to be imposed on the potential.…”

Section: B Effective Potential and Equations Of Statementioning

confidence: 99%

Phase conversion in a weakly first-order quark-hadron transition

2009

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We investigate the process of phase conversion in a thermally-driven {\it weakly} first-order quark-hadron transition. This scenario is physically appealing even if the nature of this transition in equilibrium proves to be a smooth crossover for vanishing baryonic chemical potential. We construct an effective potential by combining the equation of state obtained within Lattice QCD for the partonic sector with that of a gas of resonances in the hadronic phase, and present numerical results on bubble profiles, nucleation rates and time evolution, including the effects from reheating on the dynamics for different expansion scenarios. Our findings confirm the standard picture of a cosmological first-order transition, in which the process of phase conversion is entirely dominated by nucleation, also in the case of a weakly first-order transition. On the other hand, we show that, even for expansion rates much lower than those expected in high-energy heavy ion collisions, nucleation is very unlikely, indicating that the main mechanism of phase conversion is spinodal decomposition. Our results are compared to those obtained for a strongly first-order transition, as the one provided by the MIT bag model.Comment: 12 pages, 10 figures; v2: 1 reference added, minor modifications, matches published versio

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“…Therefore, we have all the ingredients to calculate the determinant of G. Numerical results will be presented in a future publication [11].…”

Section: Introductionmentioning

confidence: 99%

Semiclassical calculation of decay rates

2009

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Several relevant aspects of quantum-field processes can be well described by semiclassical methods. In particular, the knowledge of non-trivial classical solutions of the field equations, and the thermal and quantum fluctuations around them, provide non-perturbative information about the theory. In this work, we discuss the calculation of the one-loop effective action from the semiclasssical viewpoint. We intend to use this formalism to obtain an accurate expression for the decay rate of non-static metastable states.

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Functional density matrix formulation of quantum statistics

Cited by 5 publications

References 26 publications

Quantum statistical correlations in thermal field theories: Boundary effective theory

Quantum statistical correlations in thermal field theories: Boundary effective theory

Phase conversion in a weakly first-order quark-hadron transition

Semiclassical calculation of decay rates

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