43,374 research outputs found
Effects of density-dependent quark mass on phase diagram of three-flavor quark matter
Considering the density dependence of quark mass, we investigate the phase
transition between the (unpaired) strange quark matter and the
color-flavor-locked matter, which are supposed to be two candidates for the
ground state of strongly interacting matter. We find that if the current mass
of strange quark is small, the strange quark matter remains stable unless
the baryon density is very high. If is large, the phase transition from
the strange quark matter to the color-flavor-locked matter in particular to its
gapless phase is found to be different from the results predicted by previous
works. A complicated phase diagram of three-flavor quark matter is presented,
in which the color-flavor-locked phase region is suppressed for moderate
densities.Comment: 4 figure
Fluctuations in mixtures of lamellar- and nonlamellar-forming lipids
We consider the role of nonlamellar-forming lipids in biological membranes by
examining fluctuations, within the random phase approximation, of a model
mixture of two lipids, one of which forms lamellar phases while the other forms
inverted hexagonal phases. To determine the extent to which nonlamellar-forming
lipids facilitiate the formation of nonlamellar structures in lipid mixtures,
we examine the fluctuation modes and various correlation functions in the
lamellar phase of the mixture. To highlight the role fluctuations can play, we
focus on the lamellar phase near its limit of stability. Our results indicate
that in the initial stages of the transition, undulations appear in the
lamellae occupied by the tails, and that the nonlamellar-forming lipid
dominates these undulations. The lamellae occupied by the head groups pinch off
to make the tubes of the hexagonal phase. Examination of different correlations
and susceptibilities makes quantitative the dominant role of the
nonlamellar-forming lipids.Comment: 7 figures (better but larger in byte figures are available upon
resuest), submitte
X(1812) in Quarkonia-Glueball-Hybrid Mixing Scheme
Recently a (X(1812)) state with a mass near the threshold of
and has been observed by the BES collaboration in decay. It has been suggested that it is a
state. If it is true, this state fits in a mixing scheme based on quarkonia,
glueball and hybrid (QGH) very nicely where five physical states are predicted.
Together with the known , , , and
states, X(1812) completes the five members in this family. Using known
experimental data on these particles we determine the ranges of the mixing
parameters and predict decay properties for X(1812). We also discuss some
features which may be able to distinguish between four-quark and hybrid mixing
schemes.Comment: 15 pages, 2 figures, 3 table
Protein folding in hydrophobic-polar lattice model: a flexible ant colony optimization approach
This paper proposes a flexible ant colony (FAC) algorithm for solving protein folding problems based on the hydrophobic-polar square lattice model. Collaborations of novel pheromone and heuristic strategies in the proposed algorithm make it more effective in predicting structures of proteins compared with other state-of-the-art algorithms
Exploring the Latest Union2 SNIa Dataset by Using Model-Independent Parametrization Methods
We explore the cosmological consequences of the recently released Union2
sample of 557 Type Ia supernovae (SNIa). Combining this latest SNIa dataset
with the Cosmic microwave background (CMB) anisotropy data from the Wilkinson
Microwave Anisotropy Probe 7 year (WMAP7) observations and the baryon acoustic
oscillation (BAO) results from the Sloan Digital Sky Survey (SDSS) Data Release
7 (DR7), we measure the dark energy density function as a free function of redshift. Two
model-independent parametrization methods (the binned parametrization and the
polynomial interpolation parametrization) are used in this paper. By using the
statistic and the Bayesian information criterion, we find that the
current observational data are still too limited to distinguish which
parametrization method is better, and a simple model has advantage in fitting
observational data than a complicated model. Moreover, it is found that all
these parametrizations demonstrate that the Union2 dataset is still consistent
with a cosmological constant at 1 confidence level. Therefore, the
Union2 dataset is different from the Constitution SNIa dataset, which more
favors a dynamical dark energy.Comment: 11 pages, 8 figures, 2 tables, accepted for publication in PR
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