5,376 research outputs found
Fluctuations and Correlations of Conserved Charges in QCD at Finite Temperature with Effective Models
We study fluctuations of conserved charges including baryon number, electric
charge, and strangeness as well as the correlations among these conserved
charges in the 2+1 flavor Polyakov--Nambu--Jona-Lasinio model at finite
temperature. The calculated results are compared with those obtained from
recent lattice calculations performed with an improved staggered fermion action
at two values of the lattice cutoff with almost physical up and down quark
masses and a physical value for the strange quark mass. We find that our
calculated results are well consistent with those obtained in lattice
calculations except for some quantitative differences for fluctuations related
with strange quarks. Our calculations indicate that there is a pronounced cusp
in the ratio of the quartic to quadratic fluctuations of baryon number, i.e.
, at the critical temperature during the phase
transition, which confirms that is a useful probe
of the deconfinement and chiral phase transition.Comment: 24 pages, 11 figures; final version published in Phys. Rev.
Entanglement R\'enyi -entropy
We study the entanglement R\'{e}nyi -entropy (ERE) as the
measure of entanglement. Instead of a single quantity in standard entanglement
quantification for a quantum state by using the von Neumann entropy for the
well-accepted entanglement of formation (EoF), the ERE gives a
continuous spectrum parametrized by variable as the entanglement
measure, and it reduces to the standard EoF in the special case . The ERE provides more information in entanglement
quantification, and can be used such as in determining the convertibility of
entangled states by local operations and classical communication. A series of
new results are obtained: (i) we can show that ERE of two states,
which can be mixed or pure, may be incomparable, in contrast to the fact that
there always exists an order for EoF of two states; (ii) similar as the case of
EoF, we study in a fully analytical way the ERE for arbitrary
two-qubit states, the Werner states and isotropic states in general
d-dimension; (iii) we provide a proof of the previous conjecture for the
analytical functional form of EoF of isotropic states in arbitrary d-dimension.Comment: 11 pages, 4 figure
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