17,006 research outputs found
Universal Reduction of Effective Coordination Number in the Quasi-One-Dimensional Ising Model
Critical temperature of quasi-one-dimensional general-spin Ising ferromagnets
is investigated by means of the cluster Monte Carlo method performed on
infinite-length strips, L times infty or L times L times infty. We find that in
the weak interchain coupling regime the critical temperature as a function of
the interchain coupling is well-described by a chain mean-field formula with a
reduced effective coordination number, as the quantum Heisenberg
antiferromagnets recently reported by Yasuda et al. [Phys. Rev. Lett. 94,
217201 (2005)]. It is also confirmed that the effective coordination number is
independent of the spin size. We show that in the weak interchain coupling
limit the effective coordination number is, irrespective of the spin size,
rigorously given by the quantum critical point of a spin-1/2 transverse-field
Ising model.Comment: 12 pages, 6 figures, minor modifications, final version published in
Phys. Rev.
Incommensurate magnetism in cuprate materials
In the low doping region an incommensurate magnetic phase is observed in
LSCO. By means of the composite operator method we show that the single-band 2D
Hubbard model describes the experimental situation. In the higher doping
region, where experiments are not available, the incommensurability is
depressed owing to the van Hove singularity near the Fermi level. A
proportionality between the incommensurability amplitude and the critical
temperature is predicted, suggesting a close relation between superconductivity
and incommensurate magnetism.Comment: 4 pages, 5 figures in one Postscript file, RevTe
Entanglement Cost of Antisymmetric States and Additivity of Capacity of Some Quantum Channel
We study the entanglement cost of the states in the contragredient space,
which consists of -dimensional systems. The cost is always ebits when the state is divided into bipartite \C^d \otimes
(\C^d)^{d-2}. Combined with the arguments in \cite{Matsumoto02}, additivity of
channel capacity of some quantum channels is also shown.Comment: revtex 4 pages, no figures, small changes in title and author's
affiliation and some typo are correcte
Time evolution of a thin black ring via Hawking radiation
Black objects lose their mass and angular momenta through evaporation by
Hawking radiation, and the investigation of their time evolution has a long
history. In this paper, we study this problem for a five-dimensional doubly
spinning black ring. The black ring is assumed to emit only massless scalar
particles. We consider a thin black ring with a small thickness parameter,
, which can be approximated by a boosted Kerr string locally. We
show that a thin black ring evaporates with fixing its thickness parameter
. Further, in the case of an Emparan-Reall black ring, we derive
analytic formulas for the time evolution, which has one parameter to be
evaluated numerically. We find that the lifetime of a thin black ring is
shorter by a factor of compared to a five-dimensional
Schwarzschild black hole with the same initial mass. We also study detailed
properties of the Hawking radiation from the thin black ring, including the
energy and angular spectra of emitted particles.Comment: 28 pages, 6 figure
Pure Gravity Mediation with m_{3/2} = 10-100TeV
Recently, the ATLAS and CMS collaborations reported exciting hints of a
Standard Model-like Higgs boson with a mass around 125GeV. Such a Higgs boson
mass can be easily obtained in the minimal supersymmetric Standard Model based
on the "pure gravity mediation model" where the sfermion masses and the Higgs
mass parameters are in tens to hundreds TeV range while the gauginos are in the
hundreds GeV to TeV range. In this paper, we discuss detalis of the gaugino
mass spectrum in the pure gravity mediation model. We also discuss the signals
of the model at the current and future experiments such as cosmic ray
observations and the LHC experiments. In particular, we show that the parameter
space which is consistent with the thermal leptogenesis can be fully surveyed
experimentally in the foreseeable future.Comment: 21 pages, 7 figure
Dimensional trend in CePt2In7, Ce-115 compounds, and CeIn3
We present realistic Kondo-lattice simulation results for the
recently-discovered heavy-fermion antiferromagnet CePt2In7 comparing with its
three-dimensional counterpart CeIn3 and the less two-dimensional ones,
Ce-115's. We find that the distance to the magnetic quantum critical point is
the largest for CeIn3 and the smallest for Ce-115's, and CePt2In7 falls in
between. We argue that the trend in quasi-two-dimensional materials stems from
the frequency dependence of the hybridization between Cerium 4f-electrons and
the conduction bands.Comment: 4.8 pages, 5 figure
Physical Mechanism of the d->d+is Transition
We discuss the basic physical mechanism of the d->d+is transition, which is
the currently accepted explanation for the results of tunneling experiments
into planes. Using the first-order perturbation theory, we show that the
zero-bias states drive the transition. We present various order-of-magnitude
estimates and consistency checks that support this picture.Comment: 7 pages, 2 figure
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