11,572 research outputs found
On the low-temperature phase of the three-state antiferromagnetic Potts model on the simple cubic lattice
The three-state antiferromagnetic Potts model on the simple cubic lattice is
investigated using the cluster variation method in the cube and the star-cube
approximations. The broken-sublattice-symmetry phase is found to be stable in
the whole low-temperature region, contrary to previous results obtained using a
modified cluster variation method. The tiny free energy difference between the
broken-sublattice-symmetry and the permutationally-symmetric-sublattices phases
is calculated in the two approximations and turns out to be smaller in the
(more accurate) star-cube approximation than in the cube one.Comment: 4 pages REVTeX + 2 PostScript figures, to be published in Phys. Rev.
E as a Rapid Communicatio
A Spectrophotometric Method to Determine the Inclination of Class I Objects
A new method which enables us to estimate the inclination of Class I young
stellar objects is proposed. Since Class I objects are not spherically
symmetric, it is likely that the observed feature is sensitive to the
inclination of the system. Thus, we construct a protostar model by carefully
treating two-dimensional (2D) radiative transfer and radiative equilibrium. We
show from the present 2D numerical simulations that the emergent luminosity
L_SED,which is the frequency integration of spectral energy distribution (SED),
depends strongly on the inclination of the system i, whereas the peak flux is
insensitive to i. Based on this result, we introduce a novel indicator f_L,
which is the ratio of L_SED to the peak flux, as a good measure for the
inclination. By using f_L, we can determine the inclination regardless of the
other physical parameters. The inclination would be determined by f_L within
the accuracy of +- 5 degree, if the opening angle of bipolar outflows is
specified by any other procedure. Since this spectrophotometric method is
easier than a geometrical method or a full SED fitting method, this method
could be a powerful tool to investigate the feature of protostars statistically
with observational data which will be provided by future missions, such as
SIRTF, ASTRO-F, and ALMA.Comment: 14 pages, 9 figures, accepted by Ap
Universal properties of highly frustrated quantum magnets in strong magnetic fields
The purpose of the present paper is two-fold. On the one hand, we review some
recent studies on the low-temperature strong-field thermodynamic properties of
frustrated quantum spin antiferromagnets which admit the so-called
localized-magnon eigenstates. One the other hand, we provide some complementary
new results. We focus on the linear independence of the localized-magnon
states, the estimation of their degeneracy with the help of auxiliary classical
lattice-gas models and the analysis of the contribution of these states to
thermodynamics.Comment: Paper based on the invited talk given by J. Richter at the
International Conference "Statistical Physics 2006. Condensed Matter: Theory
and Applications" dedicated to the 90th anniversary of Ilya Lifshitz
(Kharkiv, 11-15 September, 2006
Magnetic ordering of weakly coupled frustrated quantum spin chains
The ordering temperature of a quasi-one-dimensional system, consisting of
weakly interacting quantum spin-1/2 chains with antiferromagnetic
spin-frustrating couplings (or zig-zag ladder) is calculated. The results show
that a quantum critical point between two phases of the one-dimensional
subsystem plays a crucial role. If the one-dimensional subsystem is in the
antiferromagnetic-like phase in the ground state, similar to the phase of a
spin chain without frustration, weak couplings yield magnetic ordering of the
Neel type. For intra-chain spin-frustrating interactions larger than the
critical one (at which the quantum phase transition takes place), the
quasi-one-dimensional spin system manifests a spiral magnetic incommensurate
ordering. The obtained results of our quantum theory are compared with the
quasi-classical approximations. The calculated features of magnetic ordering
are expected to be generic for weakly coupled quantum spin chains with gapless
excitations and spin-frustrating nearest and next-nearest neighbor
interactions.Comment: 6 pages, 2 figure
Higgs Masses in the Minimal SUSY SO(10) GUT
We explicitly show that minimal SUSY SO(10) Higgs-Higgsino mass matrices
evaluated by various groups are mutually consistent and correct. We comment on
the corresponding results of other authors. We construct one-to-one mappings of
our approach to the approaches of other authors.Comment: 4 pages, revtex4, Changes in the paper : We agree with Ref.
hep-ph/0501025 that there there should exist equivalence mappings between
results of Higgs mass spectra calculated by three groups of authors. (in
three different approaches. However, in the Note added of the Ref.
hep-ph/0405074 v3 the wrong mapping was presented. The explicit construction
of equivalence mappings to other approches is given. Minor changes in the
text. Paper is beeing accepted for publication in Phys. Rev
A q-analogue of gl_3 hierarchy and q-Painleve VI
A q-analogue of the gl_3 Drinfel'd-Sokolov hierarchy is proposed as a
reduction of the q-KP hierarchy. Applying a similarity reduction and a
q-Laplace transformation to the hierarchy, one can obtain the q-Painleve VI
equation proposed by Jimbo and Sakai.Comment: 14 pages, IOP style, to appear in J. Phys. A Special issue "One
hundred years of Painleve VI
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