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Kenji Fukushima

Publications and source records attributed to Kenji Fukushima.

166 records · Page 10Linked to original sources
arXiv2002

Effects of chiral restoration on the behaviour of the Polyakov loop at strong coupling

We discuss the relation between the Polyakov loop and the chiral order parameter at finite temperature. For that purpose we analyse an effective model proposed by Gocksch and Ogilvie, which is constructed by the double expansion of strong coupling and large dimensionality. We make improvements in dealing with the model and then obtain plausible results for the behaviours of both the Polyakov loop and the chiral scalar condensate. The pseudo-critical temperature read from the Polyakov loop turns out to coincide exactly with that read from the chiral scalar condensate. Within the model study based on the strong coupling expansion, the coincidence of the pseudo-critical temperatures results from the fact that the jump of the Polyakov loop in the presence of dynamical quarks should signify the chiral phase transition rather than the deconfinement transition.

hep-ph↗
arXiv2002

Spectral functions in the sigma-channel near the critical end point

Spectral functions in the $σ$-channel are investigated near the chiral critical end point (CEP), that is, the point where the chiral phase transition ceases to be first-ordered in the $(μ,T)$-plane of the QCD phase diagram. At that point the $σ$ meson becomes massless in spite of explicit breaking of the chiral symmetry. It is expected that experimental signatures peculiar to CEP can be observed through spectral changes in the presence of abnormally light $σ$ mesons. As a candidate, the invariant-mass spectrum for diphoton emission is estimated with the chiral quark model incorporated. The results show the characteristic shape with a peak in the low energy region, which may serve as a signal for CEP. However, we find that the diphoton multiplicity is highly suppressed by infrared behaviors of the $σ$ meson. Experimentally, in such a low energy region below the threshold of two pions, photons from $π^0\to2γ$ are major sources of the background for the signal.

hep-ph↗
arXiv2001

Explicit conversion from the Casimir force to Planck's law of radiation

The Casimir force has its origin in finite modification of the infinite zero-point energy induced by a specific boundary condition for the spatial configuration. In terms of the imaginary-time formalism at finite temperature, the root of Planck's law of radiation can be traced back to finite modification of the infinite vacuum energy induced by the periodic boundary condition in the temporal direction. We give the explicit conversion from the Casimir force to Planck's law of radiation, which shows the apparent correspondence between the system bounded by parallel conducting plates and the thermodynamic system. The temperature inversion symmetry and the duality relation in the thermodynamics are also discussed. We conclude that the effective temperature characterized by the spatial extension should no longer be regarded as genuine temperature.

quant-ph↗