Effect of memory on relaxation in a scalar field theory

Ikeda, Takashi

doi:10.1103/physrevd.69.105018

Cited by 6 publications

(9 citation statements)

References 55 publications

(57 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We assume translational invariance in the x and y directions, thus D = 1 in Eq. (9). We have confirmed that the total energy is conserved at least to an accuracy of less than 1 percent throughout the time evolution.…”

Section: Numerical Resultssupporting

confidence: 64%

Effects of mode-mode and isospin-isospin correlations on domain formation of disoriented chiral condensates

2006

View full text Add to dashboard Cite

The effects of mode-mode and isospin-isospin correlations on nonequilibrium chiral dynamics are investigated by using the method of the time dependent variational approach with squeezed states as trial states. Our numerical simulations show that large domains of the disoriented chiral condensate (DCC) are formed due to the combined effect of the mode-mode and isospin-isospin correlations. Moreover, it is found that, when the mode-mode correlation is included, the DCC domain formation is accompanied by the amplification of the quantum fluctuation, which implies the squeezing of the state. However, neither the DCC domain formation nor the amplification of the quantum fluctuation is observed if only the isospin-isospin correlation is included. This suggests that the mode-mode coupling plays a key role in the DCC domain formation.

show abstract

Section: Numerical Resultssupporting

confidence: 64%

Effects of mode-mode and isospin-isospin correlations on domain formation of disoriented chiral condensates

2006

View full text Add to dashboard Cite

show abstract

“…Even in the quasi-particle approximation, the number changing processes are possible because of the finite memory time as was studied in Ref. [37]. We see that at early times the number changing processes 1 ↔ 3 contribute as well as 2 ↔ 2 scattering processes.…”

Section: Particle Changing Processesmentioning

confidence: 72%

“…The last term describes the decay of n p to 3 particles and its reverse. The number changing processes are allowed because of the finite memory time t − t ′ ; the energy conservation in each microscopic process can be violated [37]. We evaluated these contributions and showed then in Figs.…”

Section: B Microscopic Processes In the Kadanoff-baym Equationmentioning

confidence: 99%

Entropy production in 2D theory in the Kadanoff–Baym approach

Nishiyama

2010

Nuclear Physics A

View full text Add to dashboard Cite

We study non-equilibrium quantum dynamics of the single-component scalar field theory in 1+1 space-time dimensions on the basis of the Kadanoff-Baym equation including the next-to-leadingorder (NLO) skeleton diagrams. As an extension of the non-relativistic case, we derive relativistic kinetic entropy at the first order in the gradient expansion of the Kadanoff-Baym equations. The derived entropy satisfies the H theorem. Next we perform numerical simulations in spatially homogeneous configurations to investigate thermalization properties of the system by evaluating the system entropy. We find that at later times the kinetic entropy increases approaching the equilibrium value, although the limited time interval in the early stage invalidates the use of it.

show abstract

“…However, if they are not applied then a gradient expansion would become too cumbersome to be of use in practical calculations. The derivation of transport equations has been discussed in great detail in the literature [14,15,16,17,18,19,20,21,22,23,24,25,26]. Most discussions focus on kinetic theory employing the additional approximation of a suitable quasi-particle ansatz, which goes beyond assumptions 1) -3).…”

Section: Assumptionsmentioning

confidence: 99%

Range of validity of transport equations

Berges

Borsányi

2006

Phys. Rev. D

View full text Add to dashboard Cite

Transport equations can be derived from quantum field theory assuming a loss of information about the details of the initial state and a gradient expansion. While the latter can be systematically improved, the assumption about a memory loss is in general not controlled by a small expansion parameter. We determine the range of validity of transport equations for the example of a scalar g 2 Φ 4 theory. We solve the nonequilibrium time evolution using the threeloop 2PI effective action. The approximation includes off-shell and memory effects and assumes no gradient expansion. This is compared to transport equations to lowest order (LO) and beyond (NLO). We find that the earliest time for the validity of transport equations is set by the characteristic relaxation time scale t damp = −2ω/Σ (eq) ̺ , where −Σ (eq) ̺ /2 denotes the on-shell imaginary-part of the self-energy. This time scale agrees with the characteristic time for partial memory loss, but is much shorter than thermal equilibration times. For times larger than about t damp the gradient expansion to NLO is found to describe the "full" results rather well for g 2 1. *

show abstract

Effect of memory on relaxation in a scalar field theory

Cited by 6 publications

References 55 publications

Effects of mode-mode and isospin-isospin correlations on domain formation of disoriented chiral condensates

Effects of mode-mode and isospin-isospin correlations on domain formation of disoriented chiral condensates

Entropy production in 2D theory in the Kadanoff–Baym approach

Range of validity of transport equations

Contact Info

Product

Resources

About