18,599 research outputs found
Coupling of pion condensate, chiral condensate and Polyakov loop in an extended NJL model
The Nambu Jona-Lasinio model with a Polyakov loop is extended to finite
isospin chemical potential case, which is characterized by simultaneous
coupling of pion condensate, chiral condensate and Polyakov loop. The pion
condensate, chiral condensate and the Polyakov loop as functions of temperature
and isospin chemical potential are investigated by minimizing the thermodynamic
potential of the system. The resulting phase diagram is studied
with emphasis on the critical point and Polyakov loop dynamics. The tricritical
point for the pion superfluidity phase transition is confirmed and the phase
transition for isospin symmetry restoration in high isospin chemical potential
region perfectly coincides with the crossover phase transition for Polyakov
loop. These results are in agreement with the Lattice QCD data.Comment: 15pages, 8 figure
List (d,1)-total labelling of graphs embedded in surfaces
The (d,1)-total labelling of graphs was introduced by Havet and Yu. In this
paper, we consider the list version of (d,1)-total labelling of graphs. Let G
be a graph embedded in a surface with Euler characteristic whose
maximum degree is sufficiently large. We prove that the (d,1)-total
choosability of is at most .Comment: 6 page
Statefinder hierarchy exploration of the extended Ricci dark energy
We apply the statefinder hierarchy plus the fractional growth parameter to
explore the extended Ricci dark energy (ERDE) model, in which there are two
independent coefficients and . By adjusting them, we plot
evolution trajectories of some typical parameters, including Hubble expansion
rate , deceleration parameter , the third and fourth order hierarchy
and and fractional growth parameter ,
respectively, as well as several combinations of them. For the case of variable
and constant , in the low-redshift region the evolution
trajectories of are in high degeneracy and that of separate somewhat.
However, the CDM model is confounded with ERDE in both of these two
cases. and , especially the former, perform much better.
They can differentiate well only varieties of cases within ERDE except
CDM in the low-redshift region. For high-redshift region, combinations
can break the degeneracy. Both of
and have the ability to
discriminate ERDE with from CDM, of which the degeneracy
cannot be broken by all the before-mentioned parameters. For the case of
variable and constant , and can
only discriminate ERDE from CDM. Nothing but pairs
and can discriminate not only
within ERDE but also ERDE from CDM. Finally we find that
is surprisingly a better choice to discriminate within ERDE itself, and ERDE
from CDM as well, rather than .Comment: 8 pages, 14 figures; published versio
Effect of weak measurement on entanglement distribution over noisy channels
Being able to implement effective entanglement distribution in noisy
environments is a key step towards practical quantum communication, and
long-term efforts have been made on the development of it. Recently, it has
been found that the null-result weak measurement (NRWM) can be used to enhance
probabilistically the entanglement of a single copy of amplitude-damped
entangled state. This paper investigates remote distributions of bipartite and
multipartite entangled states in the amplitudedamping environment by combining
NRWMs and entanglement distillation protocols (EDPs). We show that the NRWM has
no positive effect on the distribution of bipartite maximally entangled states
and multipartite Greenberger-Horne-Zeilinger states, although it is able to
increase the amount of entanglement of each source state (noisy entangled
state) of EDPs with a certain probability. However, we find that the NRWM would
contribute to remote distributions of multipartite W states. We demonstrate
that the NRWM can not only reduce the fidelity thresholds for distillability of
decohered W states, but also raise the distillation efficiencies of W states.
Our results suggest a new idea for quantifying the ability of a local filtering
operation in protecting entanglement from decoherence.Comment: 15 pages, 9 figures. Minor revision has been mad
- …