43,489 research outputs found
Universal correlations of one-dimensional interacting electrons in the gas phase
We consider dynamical correlation functions of short range interacting
electrons in one dimension at finite temperature. Below a critical value of the
chemical potential there is no Fermi surface anymore, and the system can no
longer be described as a Luttinger liquid. Its low temperature thermodynamics
is that of an ideal gas. We identify the impenetrable electron gas model as a
universal model for the gas phase and present exact and explicit expressions
for the asymptotics of correlation functions at small temperatures, in the
presence of a magnetic field.Comment: 4 pages, Revte
On the location of two blow up points on an annulus for the mean field equation
We consider the mean field equation on two-dimensional annular domains, and
prove that if and are two blow up points of a blowing-up solution
sequence of the equation, then we must have .Comment: To appear in CRA
Role of Large Gluonic Excitation Energy for Narrow Width of Penta-Quark Baryons in QCD String Theory
We study the narrow decay width of low-lying penta-quark baryons in the QCD
string theoryin terms of gluonic excitations. In the QCD string theory, the
penta-quark baryon decays via a gluonic-excited state of a baryon and meson
system, where a pair of Y-shaped junction and anti-junction is created. Since
lattice QCD shows that the lowest gluonic-excitation energy takes a large value
of about 1 GeV, the decay of the penta-quark baryon near the threshold is
considered as a quantum tunneling process via a highly-excited state (a
gluonic-excited state) in the QCD string theory. This mechanism strongly
suppresses the decay and leads to an extremely narrow decay width of the
penta-quark system.Comment: Talk given at International Conference on the Structure of Baryons
(Baryons 04) October 25 - 29, 2004, Ecole Polytechnique, Palaiseau, Franc
Relationship between single-particle excitation and spin excitation at the Mott Transition
An intuitive interpretation of the relationship between the dispersion
relation of the single-particle excitation in a metal and that of the spin
excitation in a Mott insulator is presented, based on the results for the one-
and two-dimensional Hubbard models obtained by using the Bethe ansatz,
dynamical density-matrix renormalization group method, and cluster perturbation
theory. The dispersion relation of the spin excitation in the Mott insulator is
naturally constructed from that of the single-particle excitation in the
zero-doping limit in both one- and two-dimensional Hubbard models, which allows
us to interpret the doping-induced states as the states that lose charge
character toward the Mott transition. The characteristic feature of the Mott
transition is contrasted with the feature of a Fermi liquid and that of the
transition between a band insulator and a metal.Comment: 6 pages, 2 figures, to appear in JPS Conf. Pro
Low-lying Dirac eigenmodes and monopoles in 3+1D compact QED
We study the properties of low-lying Dirac modes in quenched compact QED at
, employing () lattices and the
overlap formalism for the fermion action. We pay attention to the spatial
distributions of low-lying Dirac modes below and above the ``phase transition
temperature'' . Near-zero modes are found to have universal
anti-correlations with monopole currents, and are found to lose their temporal
structures above exhibiting stronger spatial localization properties. We
also study the nearest-neighbor level spacing distribution of Dirac eigenvalues
and find a Wigner-Poisson transition.Comment: 10 pages, 10 figures, 1 tabl
Flat Spectrum X-ray Emission from the Direction of a Molecular Cloud Associated with SNR RX J1713.7-3946
We report on the discovery of a hard X-ray source with ASCA from a molecular
cloud in the vicinity of the SNR RX J1713.7-3946. The energy spectrum (1--10
keV) shows a flat continuum which is described by a power-law with photon index
1.0 +-0.4. We argue that this unusually flat spectrum can be best interpreted
in terms of characteristic bremsstrahlung emission from the
ionization-loss-flattened distribution of either sub-relativistic protons or
mildly-relativistic electrons. The strong shock of the SNR RX J1713.7-3946,
which presumably interacts with the molecular cloud, as evidenced by
observations of CO-lines, seems to be a natural site of acceleration of such
sub- or mildly-relativistic nonthermal particles. However, the observed X-ray
luminosity of 1.7 10^35 erg/s (for 6 kpc distance) requires that a huge kinetic
energy of about 10^50 erg be released in the form of nonthermal particles to
illuminate the cloud. The shock-acceleration at RX J1713.7-3946 can barely
satisfy this energetic requirement, unless (i) the source is located much
closer than 6 kpc and/or (ii) the mechanical energy of the explosion
essentially exceeds 10^51 erg. Another possibility would be that an essential
part of the "lost" energy is somehow converted to plasma waves, which return
this energy to nonthermal particles through their turbulent reacceleration on
plasma waves. Irrespective of mechanisms responsible for production of
high-energy particles, the flat X-ray emission seems to be a signature of a new
striking energetic phenomenon in molecular clouds.Comment: 6 pages, 2 figures, Accepted for publication in PAS
Galilei covariance and (4,1) de Sitter space
A vector space G is introduced such that the Galilei transformations are
considered linear mappings in this manifold. The covariant structure of the
Galilei Group (Y. Takahashi, Fortschr. Phys. 36 (1988) 63; 36 (1988) 83) is
derived and the tensor analysis is developed. It is shown that the Euclidean
space is embedded the (4,1) de Sitter space through in G. This is an
interesting and useful aspect, in particular, for the analysis carried out for
the Lie algebra of the generators of linear transformations in G.Comment: Late
Three Dimensional Heisenberg Spin Glass Models with and without Random Anisotropy
We reexamine the spin glass (SG) phase transition of the Heisenberg
models with and without the random anisotropy in three dimensions ()
using complementary two methods, i.e., (i) the defect energy method and (ii)
the Monte Carlo method. We reveal that the conventional defect energy method is
not convincing and propose a new method which considers the stiffness of the
lattice itself. Using the method, we show that the stiffness exponent
has a positive value () even when . Considering the
stiffness at finite temperatures, we obtain the SG phase transition temperature
of for . On the other hand, a large scale MC
simulation shows that, in contrary to the previous results, a scaling plot of
the SG susceptibility for is obtained using almost the
same transiton temperature of . Hence we believe that
the SG phase transition occurs in the Heisenberg SG model in .Comment: 15 pages, 9 figures, to be published in J. Phys.
Quantum Spin Chains and Riemann Zeta Function with Odd Arguments
Riemann zeta function is an important object of number theory. It was also
used for description of disordered systems in statistical mechanics. We show
that Riemann zeta function is also useful for the description of integrable
model. We study XXX Heisenberg spin 1/2 anti-ferromagnet. We evaluate a
probability of formation of a ferromagnetic string in the anti-ferromagnetic
ground state in thermodynamics limit. We prove that for short strings the
probability can be expressed in terms of Riemann zeta function with odd
arguments.Comment: LaTeX, 7 page
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