2,833 research outputs found
Pionic BEC--BCS crossover at finite isospin chemical potential
We study the character change of the pionic condensation at finite isospin
chemical potential \mu_\mathrm{I} by adopting the linear sigma model as a
non-local interaction between quarks. At low |\mu_\mathrm{I}| the condensation
is purely bosonic, then the Cooper pairing around the Fermi surface grows
gradually as |\mu_\mathrm{I}| increases. This q-\bar q pairing is weakly
coupled in comparison with the case of the q-q pairing that leads to color
superconductivity.Comment: 17 pages, 3 figures, typos in eq.(6) and refs.[37] and [41] are
corrected, published in Phys. Rev.
Black Hole Thermodynamics and Riemann Surfaces
We use the analytic continuation procedure proposed in our earlier works to
study the thermodynamics of black holes in 2+1 dimensions. A general black hole
in 2+1 dimensions has g handles hidden behind h horizons. The result of the
analytic continuation is a hyperbolic 3-manifold having the topology of a
handlebody. The boundary of this handlebody is a compact Riemann surface of
genus G=2g+h-1. Conformal moduli of this surface encode in a simple way the
physical characteristics of the black hole. The moduli space of black holes of
a given type (g,h) is then the Schottky space at genus G. The (logarithm of
the) thermodynamic partition function of the hole is the Kaehler potential for
the Weil-Peterson metric on the Schottky space. Bekenstein bound on the black
hole entropy leads us to conjecture a new strong bound on this Kaehler
potential.Comment: 17+1 pages, 9 figure
Analytic Continuation for Asymptotically AdS 3D Gravity
We have previously proposed that asymptotically AdS 3D wormholes and black
holes can be analytically continued to the Euclidean signature. The analytic
continuation procedure was described for non-rotating spacetimes, for which a
plane t=0 of time symmetry exists. The resulting Euclidean manifolds turned out
to be handlebodies whose boundary is the Schottky double of the geometry of the
t=0 plane. In the present paper we generalize this analytic continuation map to
the case of rotating wormholes. The Euclidean manifolds we obtain are quotients
of the hyperbolic space by a certain quasi-Fuchsian group. The group is the
Fenchel-Nielsen deformation of the group of the non-rotating spacetime. The
angular velocity of an asymptotic region is shown to be related to the
Fenchel-Nielsen twist. This solves the problem of classification of rotating
black holes and wormholes in 2+1 dimensions: the spacetimes are parametrized by
the moduli of the boundary of the corresponding Euclidean spaces. We also
comment on the thermodynamics of the wormhole spacetimes.Comment: 28 pages, 14 figure
Hinode Calibration for Precise Image Co-alignment between SOT and XRT (November 2006 -- April 2007)
To understand the physical mechanisms for activity and heating in the solar
atmosphere, the magnetic coupling from the photosphere to the corona is an
important piece of information from the Hinode observations, and therefore
precise positional alignment is required among the data acquired by different
telescopes. The Hinode spacecraft and its onboard telescopes were developed to
allow us to investigate magnetic coupling with co-alignment accuracy better
than 1 arcsec. Using the Mercury transit observed on 8 November 2006 and
co-alignment measurements regularly performed on a weekly basis, we have
determined the information necessary for precise image co-alignment and have
confirmed that co-alignment better than 1 arcsec can be realized between Solar
Optical Telescope (SOT) and X-Ray Telescope (XRT) with our baseline
co-alignment method. This paper presents results from the calibration for
precise co-alignment of CCD images from SOT and XRT.Comment: 8 pages, 9 figures, accepted for publication in PASJ (Hinode Special
issue
Quasiparticles and Energy Scaling in BiSrCaCuO (=1-3): Angle-Resolved Photoemission Spectroscopy
Angle-resolved photoemission spectroscopy (ARPES) has been performed on the
single- to triple-layered Bi-family high-{\it T} superconductors
(BiSrCaCuO, =1-3). We found a sharp
quasiparticle peak as well as a pseudogap at the Fermi level in the
triple-layered compound. Comparison among three compounds has revealed a
universal rule that the characteristic energies of superconducting and
pseudogap behaviors are scaled with the maximum {\it T}.Comment: 4 pages, 4 figure
Spatial structure of quark Cooper pairs in a color superconductor
Spatial structure of Cooper pairs with quantum numbers color 3^*, I=J=L=S=0
in ud 2 flavor quark matter is studied by solving the gap equation and
calculating the coherence length in full momentum range without the weak
coupling approximation. Although the gap at the Fermi surface and the coherence
length depend on density weakly, the shape of the r-space pair wave function
varies strongly with density. This result indicates that quark Cooper pairs
become more bosonic at higher densities.Comment: 10 pages, 3 figures. The frequency dependence of the gap and the
limitation on the type I/type II discussion are mentioned briefly. To appear
in Phys. Rev.
Dirac Sea Effects on Superfluidity in Nuclear Matter
We study two kinds of Dirac sea effects on the pairing gap in nuclear
matter based on the relativistic Hartree approximation to quantum hadrodynamics
and the Gor'kov formalism. We show that the vacuum fluctuation effect on the
nucleon effective mass is more important than the direct coupling between the
Fermi sea and the Dirac sea due to the pairing interaction. The effects of the
high-momentum cutoff are also discussed.Comment: 11 pages, 3 eps figures included, uses REVTeX (with \tightenlines
Genomic structure and cloned cDNAs predict that four variants in the kinase domain of serine/threonine kinase receptors arise by alternative splicing and poly(A) addition.
Meson mass at real and imaginary chemical potentials
The chemical-potential dependence of pi and sigma meson masses is analyzed at
both real and imaginary chemical potentials, and
, by using the Polyakov-loop extended Nambu--Jona-Lasinio
(PNJL) model that possesses both the extended symmetry and the
chiral symmetry. In the region, the meson masses have the
Roberge-Weiss periodicity. Assuming that the meson masses will be measured at
finite by lattice QCD in future, we simulate how meson masses
at finite are extracted from those at finite ,
and propose a reliable extraction method.Comment: 8 pages, 6 figures, typo corrected, some discussions clarified,
version accepted for publication in Phys. Rev.
Scattering mechanism in a step-modulated subwavelength metal slit: a multi-mode multi-reflection analysis
In this paper, the scattering/transmission inside a step-modulated
subwavelength metal slit is investigated in detail. We firstly investigate the
scattering in a junction structure by two types of structural changes. The
variation of transmission and reflection coefficients depending on structural
parameters are analyzed. Then a multi-mode multi-reflection model based on ray
theory is proposed to illustrate the transmission in the step-modulated slit
explicitly. The key parts of this model are the multi-mode excitation and the
superposition procedure of the scatterings from all possible modes, which
represent the interference and energy transfer happened at interfaces. The
method we use is an improved modal expansion method (MEM), which is a more
practical and efficient version compared with the previous one [Opt. Express
19, 10073 (2011)]. In addition, some commonly used methods, FDTD, scattering
matrix method, and improved characteristic impedance method, are compared with
MEM to highlight the preciseness of these methods.Comment: 25 pages, 9 figure
- …