17,483 research outputs found
Top quark forward-backward asymmetry and charge asymmetry in left-right twin Higgs model
In order to explain the Tevatron anomaly of the top quark forward-backward
asymmetry in the left-right twin Higgs model, we choose to give up
the lightest neutral particle of field as a stable dark matter
candidate. Then a new Yukawa interaction for is allowed, which can be
free from the constraint of same-sign top pair production and contribute
sizably to . Considering the constraints from the production rates of
the top pair (), the top decay rates and invariant mass
distribution, we find that this model with such new Yukawa interaction can
explain measured at the Tevatron while satisfying the charge
asymmetry measured at the LHC.Moreover, this model predicts a
strongly correlation between at the LHC and at the
Tevatron, i.e., increases as increases.Comment: 17 pages, 9 figures; matches the published versio
Asymmetric Properties of Heat Conduction in a One-Dimensional Frenkel-Kontorova Model
In this Letter, we show numerically that the rectifying effect of heat flux
in a one-dimensional two-segment Frenkel-Kontorova chain demonstrated in recent
literature is merely available under the limit of the weak coupling between the
two constituent segments. Surprisingly, the rectifying effect will be reversed
when the properties of the interface and the system size change. The two types
of asymmetric heat conduction are dominated by different mechanisms, which are
all induced by the nonlinearity. We further discuss the possibility of the
experimental realization of thermal diode or rectifier devices.Comment: 4 Pages, 4 figure
Steady-State Analysis of Load Balancing with Coxian- Distributed Service Times
This paper studies load balancing for many-server ( servers) systems. Each
server has a buffer of size and can have at most one job in service and
jobs in the buffer. The service time of a job follows the Coxian-2
distribution. We focus on steady-state performance of load balancing policies
in the heavy traffic regime such that the normalized load of system is for We identify a set of policies that
achieve asymptotic zero waiting. The set of policies include several classical
policies such as join-the-shortest-queue (JSQ), join-the-idle-queue (JIQ),
idle-one-first (I1F) and power-of--choices (Po) with . The proof of the main result is based on Stein's method and state space
collapse. A key technical contribution of this paper is the iterative state
space collapse approach that leads to a simple generator approximation when
applying Stein's method
Glassy Dynamics in a Frustrated Spin System: Role of Defects
In an effort to understand the glass transition, the kinetics of a spin model
with frustration but no quenched randomness has been analyzed. The
phenomenology of the spin model is remarkably similiar to that of structural
glasses. Analysis of the model suggests that defects play a major role in
dictating the dynamics as the glass transition is approached.Comment: 9 pages, 5 figures, accepted in J. Phys.: Condensed Matter,
proceedings of the Trieste workshop on "Unifying Concepts in Glass Physics
-meson in nuclear matter
The -nucleon (N) interactions are deduced from the heavy baryon
chiral perturbation theory up to the next-to-leading-order terms. Combining the
relativistic mean-field theory for nucleon system, we have studied the
in-medium properties of -meson. We find that all the elastic scattering
N interactions come from the next-to-leading-order terms. The N
sigma term is found to be about 280130 MeV. The off-shell terms are also
important to the in-medium properties of -meson. On application of the
latest determination of the N scattering length, the ratio of
-meson effective mass to its vacuum value is near , while
the optical potential is about MeV, at the normal nuclear density.Comment: 8 pages, 3 figures, to appear in PRC, many modification
Effective Field Theory of the Zero-Temperature Triangular-Lattice Antiferromagnet: A Monte Carlo Study
Using a Monte Carlo coarse-graining technique introduced by Binder et al., we
have explicitly constructed the continuum field theory for the zero-temperature
triangular Ising antiferromagnet. We verify the conjecture that this is a
gaussian theory of the height variable in the interface representation of the
spin model. We also measure the height-height correlation function and deduce
the stiffness constant. In addition, we investigate the nature of defect-defect
interactions at finite temperatures, and find that the two-dimensional Coulomb
gas scenario applies at low temperatures.Comment: 26 pages, 9 figure
Long range scattering effects on spin Hall current in -type bulk semiconductors
Employing a nonequilibrium Green's function approach, we examine the effects
of long-range hole-impurity scattering on spin-Hall current in -type bulk
semiconductors within the framework of the self-consistent Born approximation.
We find that, contrary to the null effect of short-range scattering on
spin-Hall current, long-range collisions do produce a nonvanishing contribution
to the spin-Hall current, which is independent of impurity density in the
diffusive regime and relates only to hole states near the Fermi surface. The
sign of this contribution is opposite to that of the previously predicted
disorder-independent spin-Hall current, leading to a sign change of the total
spin-Hall current as hole density varies. Furthermore, we also make clear that
the disorder-independent spin-Hall effect is a result of an interband
polarization directly induced by the dc electric field with contributions from
all hole states in the Fermi sea.Comment: 9 pages, 1 figur
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