1,614 research outputs found
Random matrix model at nonzero chemical potentials with anomaly effects
Phase diagram of the chiral random matrix model with U(1)A breaking term is
studied with the quark chemical potentials varied independently at zero
temperature, by taking the chiral and meson condensates as the order
parameters. Although, without the U(1)A breaking term, chiral transition of
each flavor can happen separately responding to its chemical potential, the
U(1)A breaking terms mix the chiral condensates and correlate the phase
transitions. In the three flavor case, we find that there are mixings between
the meson and chiral condensates due to the U(1)A anomaly, which makes the
meson condensed phase more stable. Increasing the hypercharge chemical
potential () with the isospin and quark chemical potentials (,
) kept small, we observe that the kaon condensed phase becomes the
ground state and at the larger the pion condense phase appears
unexpectedly, which is caused by the competition between the chiral restoration
and the meson condensation. The similar happens when and are
exchanged, and the kaon condensed phase becomes the ground state at larger
below the full chiral restoration.Comment: 12 pages, 8 figure
Stability of color-flavor locked strangelets
The stability of color-flavor locked (CFL) strangelets is studied in the
three-flavor Nambu--Jona-Lasinio model. We consider all quark flavors to be
massless, for simplicity. By making use of the multiple reflection expansion,
we explicitly take into account finite size effects and formulate the
thermodynamic potential for CFL strangelets. We find that the CFL gap could be
large enough so that the energy per baryon number of CFL strangelets is greatly
affected. In addition, if the quark-quark coupling constant is larger than a
certain critical value, there is a possibility of finding absolutely stable CFL
strangelets.Comment: 7 pages, 3 figures, to appear in Int. J. Mod. Phys.
Non-Abelian Stokes Theorem and Quark Confinement in SU(3) Yang-Mills Gauge Theory
We derive a new version of SU(3) non-Abelian Stokes theorem by making use of
the coherent state representation on the coset space , the flag space. Then we outline a derivation of the area law of the
Wilson loop in SU(3) Yang-Mills theory in the maximal Abelian gauge (The
detailed exposition will be given in a forthcoming article). This derivation is
performed by combining the non-Abelian Stokes theorem with the reformulation of
the Yang-Mills theory as a perturbative deformation of a topological field
theory recently proposed by one of the authors. Within this framework, we show
that the fundamental quark is confined even if is broken by partial
gauge fixing into just as is broken to . An
origin of the area law is related to the geometric phase of the Wilczek-Zee
holonomy for U(2). Abelian dominance is an immediate byproduct of these results
and magnetic monopole plays the dominant role in this derivation.Comment: 14 pages, Latex, no figures, version accepted for publication in Mod.
Phys. Lett. A (some comments are added in the final parts
Black ring formation in particle systems
It is known that the formation of apparent horizons with non-spherical
topology is possible in higher-dimensional spacetimes. One of these is the
black ring horizon with topology where is the spacetime
dimension number. In this paper, we investigate the black ring horizon
formation in systems with -particles. We analyze two kinds of system: the
high-energy -particle system and the momentarily-static -black-hole
initial data. In the high-energy particle system, we prove that the black ring
horizon does not exist at the instant of collision for any . But there
remains a possibility that the black ring forms after the collision and this
result is not sufficient. Because calculating the metric of this system after
the collision is difficult, we consider the momentarily-static -black-hole
initial data that can be regarded as a simplified -particle model and
numerically solve the black ring horizon that surrounds all the particles. Our
results show that there is the minimum particle number that is necessary for
the black ring formation and this number depends on . Although many particle
number is required in five-dimensions, is sufficient for the black ring
formation in the cases. The black ring formation becomes easier for
larger . We provide a plausible physical interpretation of our results and
discuss the validity of Ida and Nakao's conjecture for the horizon formation in
higher-dimensions. Finally we briefly discuss the probable methods of producing
the black rings in accelerators.Comment: 26 pages, 7 figure
Volume Expansion of Swiss-Cheese Universe
In order to investigate the effect of inhomogeneities on the volume expansion
of the universe, we study modified Swiss-Cheese universe model. Since this
model is an exact solution of Einstein equations, we can get an insight into
non-linear dynamics of inhomogeneous universe from it. We find that
inhomogeneities make the volume expansion slower than that of the background
Einstein-de Sitter universe when those can be regarded as small fluctuations in
the background universe. This result is consistent with the previous studies
based on the second order perturbation analysis. On the other hand, if the
inhomogeneities can not be treated as small perturbations, the volume expansion
of the universe depends on the type of fluctuations. Although the volume
expansion rate approaches to the background value asymptotically, the volume
itself can be finally arbitrarily smaller than the background one and can be
larger than that of the background but there is an upper bound on it.Comment: 22 pages, 7 figures, to be submitted to Phys. Rev.
Two photon decay of and at finite temperature and density
A comparative study of the anomalous decays , at
finite temperature and at finite density, is performed in the framework of the
three--flavor Nambu--Jona-Lasinio. The similarities and differences between
both scenarios are discussed. In both cases the lifetimes of these mesons
decrease significantly at the critical point, although this might not be
sufficient to observe enhancement of these decays in heavy-ion collisions.Comment: 5 pages, 1 figure. Talk given at Strange Quark Matter 2004, Cape
Town, South Africa, 15-20 September, 200
Unusual superexchange pathways in a Ni triangular lattice of NiGaS with negative charge-transfer energy
We have studied the electronic structure of the Ni triangular lattice in
NiGaS using photoemission spectroscopy and subsequent model
calculations. The cluster-model analysis of the Ni 2 core-level spectrum
shows that the S 3 to Ni 3 charge-transfer energy is -1 eV and the
ground state is dominated by the configuration ( is a S 3 hole).
Cell perturbation analysis for the NiS triangular lattice indicates that
the strong S 3 hole character of the ground state provides the enhanced
superexchange interaction between the third nearest neighbor sites.Comment: 10 pages, 5 figures, accepted to PR
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