567 research outputs found
Two aspects of color superconductivity: gauge independence and neutrality
A formal proof is given that the fermionic quasiparticle dispersion laws in a
color superconductor are gauge independent. It is shown that the gluon (photon)
field acquires a non-vanishing expectation value in a color superconductor,
which is related to color (electric) neutrality.Comment: 5 pages, to appear in the proceedings of SEWM 2004, Helsinki, 16-19
June 200
Anomalous specific heat in ultradegenerate QED and QCD
We discuss the origin of the anomalous behavior of the
low-temperature entropy and specific heat in ultradegenerate QED and QCD and
report on a recent calculation which is complete to leading order in the
coupling and which contains an infinite series of anomalous terms involving
also fractional powers in . This result involves dynamical hard-dense-loop
resummation and interpolates between Debye screening effects at larger
temperatures and non-Fermi-liquid behavior from only dynamically screened
magnetic fields at low temperature.Comment: 5 pages, 3 figures, contribution to the Proceedings of Strong and
Electroweak Matter 2004 (SEWM04), Helsinki, Finland, 16-19 Jun 200
Meson current in the CFL phase
We study the stability of the color-flavor locked (CFL) phase of dense quark
matter with regard to the formation of a non-zero Goldstone boson current. We
show that an instability appears in the vicinity of the point
which marks the appearance of gapless fermion modes in the CFL phase. Here,
is the shift in chemical potential due to the strange
quark mass and is the gap in the chiral limit. We show that in the
Goldstone boson current phase all components of the magnetic screening mass are
real. In this work we do not take into account homogeneous kaon condensation.
We study the effects of an instanton induced interaction of the magnitude
required to suppress kaon condensation.Comment: 15 pages, 5 figures, v2: minor improvements, results unchange
Goldstone boson currents in a kaon condensed CFL phase
We study the stability of the kaon condensed color-flavor locked (CFL) phase
of dense quark matter with regard to the formation of a non-zero Goldstone
boson current. In the kaon condensed phase there is an electrically charged
fermion which becomes gapless near \mu_s^(1) \simeq 1.35\Delta and a neutral
fermion which becomes gapless near \mu_s^(2)\simeq 1.61\Delta. Here,
\mu_s=m_s^2/(2p_F) is the shift in the Fermi energy due to the strange quark
mass m_s and \Delta is the gap in the chiral limit. The transition to the
gapless phase is continuous at \mu_s^(1) and first order at \mu_s^(2). We find
that the magnetic screening masses are real in the regime \mu_s< \mu_s^(2), but
some screening masses are imaginary for \mu_s> \mu_s^(2). We show that there is
a very weak current instability for \mu_s>\mu_s^(1) and a more robust
instability in a small window near \mu_s^(2). We also show that in the
Goldstone boson current phase all components of the magnetic screening mass are
real. There is a range of values of \mu_s below 2\Delta in which the magnetic
gluon screening masses are imaginary but the phase is stable with respect to
electrically neutral fluctuations of the gauge field.Comment: 16 page
Extreme self-organization in networks constructed from gene expression data
We study networks constructed from gene expression data obtained from many
types of cancers. The networks are constructed by connecting vertices that
belong to each others' list of K-nearest-neighbors, with K being an a priori
selected non-negative integer. We introduce an order parameter for
characterizing the homogeneity of the networks. On minimizing the order
parameter with respect to K, degree distribution of the networks shows
power-law behavior in the tails with an exponent of unity. Analysis of the
eigenvalue spectrum of the networks confirms the presence of the power-law and
small-world behavior. We discuss the significance of these findings in the
context of evolutionary biological processes.Comment: 4 pages including 3 eps figures, revtex. Revisions as in published
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