8,096 research outputs found
On the steady state probability distribution of nonequilibrium stochastic systems
A driven stochastic system in a constant temperature heat bath relaxes into a
steady state which is characterized by the steady state probability
distribution. We investigate the relationship between the driving force and the
steady state probability distribution. We adopt the force decomposition method
in which the force is decomposed as the sum of a gradient of a steady state
potential and the remaining part. The decomposition method allows one to find a
set of force fields each of which is compatible to a given steady state. Such a
knowledge provides a useful insight on stochastic systems especially in the
nonequilibrium situation. We demonstrate the decomposition method in stochastic
systems under overdamped and underdamped dynamics and discuss the connection
between them.Comment: 8 page
1-loop Corrections to the \rho Parameter in the Left-Right Twin Higgs Model
We implement a one-loop analysis of the parameter in the Left Right
Twin Higgs model, including the logarithmically enhanced contributions from
both fermion and scalar loops. Numerical results show that the one-loop
contributions are dominant over the tree level corrections in most regions of
parameter space. The experimentally allowed values of -parameter divide
the allowed parameter space into two regions; less than and
larger than roughly, for symmetry breaking scale . Our
numerical analysis significantly reduces the parameter space which are
favorably accessible to the LHC.Comment: Submitted for the SUSY07 proceedings, 4 pages, 3 eps figure
One-loop Radiative Corrections to the Parameter in the Left Right Twin Higgs Model
We implement a one-loop analysis of the parameter in the Left Right
Twin Higgs model, including the logarithmically enhanced contributions from
both heavy fermion and scalar loops. Numerical analysis indicates that the
one-loop corrections are dominant over the tree-level contributions in most
regions of parameter space. The experimentally allowed values of the
-parameter divide the allowed parameter space into two regions; less than
and larger than roughly, for the symmetry
breaking scale . Therefore our result significantly reduces the parameter
space which are favorably accessible to the LHC.Comment: minor revisio
Longitudinal top polarization as a probe of a possible origin of forward-backward asymmetry of the top quark at the Tevatron
If the forward-backward (FB) asymmetry of top quark () observed
at the Tevatron deviates from the SM prediction, there must be -violating
interactions in . This new interaction will
necessarily affect the top spin polarization. In this letter, we perform a
model independent analysis on the longitudinal (anti)top polarization (
and ) using an effective lagrangian with dim-6 four-quark operators
relevant for , and show that the -odd
observable corresponding to the polarization difference
gives important informations on the chiral structures of new physics that might
be relevant to the .Comment: 8 pages, 5 figures, to appear in PL
Complete Condensation in a Zero Range Process on Scale-Free Networks
We study a zero range process on scale-free networks in order to investigate
how network structure influences particle dynamics. The zero range process is
defined with the particle jumping rate function . We show
analytically that a complete condensation occurs when where is the degree distribution exponent of the
underlying networks. In the complete condensation, those nodes whose degree is
higher than a threshold are occupied by macroscopic numbers of particles, while
the other nodes are occupied by negligible numbers of particles. We also show
numerically that the relaxation time follows a power-law scaling with the network size and a dynamic exponent in the condensed
phase.Comment: 4 pages, 2 EPS figures, and 1 table (some revision for relational
dynamics parts
Mass and rapidity dependent top quark forward-backward asymmetry in the effective Lagrangian approach
We study the invariant mass and rapidity dependent top quark forward-backward
asymmetry from the effective Lagrangian viewpoint. The Wilson coefficients are
constrained by the experimental observations and the concrete models that
reproduce the low energy effective Lagaragians are considered. Some of them are
disfavored and others relatively favored. For each cases, we estimate the
appropriacy of the effective Lagrangian approach.Comment: To appear in the proceedings of Top 2012, 5th International Workshop
on Top Quark Physics, September 16-21, 2012, Winchester, U.
Particle Condensation in Pair Exclusion Process
Condensation is characterized with a single macroscopic condensate whose mass
is proportional to a system size . We demonstrate how important particle
interactions are in condensation phenomena. We study a modified version of the
zero-range process by including a pair exclusion. Each particle is associated
with its own partner, and particles of a pair are forbidden to stay at the same
site. The pair exclusion is weak in that a particle interacts with only a
single one among all others. It turns out that such a weak interaction changes
the nature of condensation drastically. There appear a number of mesoscopic
condensates: the mass of a condensate scales as and
the number of condensates scales as with a
logarithmic correction. These results are derived analytically through a
mapping to a solvable model under a certain assumption, and confirmed
numerically.Comment: 4 pages, 2 figur
Measurement of effective thermal conductivity of LaNi powder packed bed
Effective thermal conductivity of LaNi powder packed bed was analyzed
with customized guarded hot-plate (GHP) apparatus. Here, GHP was designed for
precise measurement of effective thermal conductivity of metal-hydride powders
even with small sample amounts (2.1210 mm). Dimensions of
sample container and apparatus were determined through two-dimensional (2-D)
steady-state heat conduction analysis. Calibration experiment and uncertainty
analysis were conducted to validate the accuracy of the GHP. Based on the
measurements of the residual thermal conductivity of the LaNi packed bed,
effect of particle size on contact factor of LaNi packed bed was estimated.
By applying the Yagi and Kunii (YK) model to the effective thermal conductivity
of LaNi packed bed, effect of contact factor and gas thermal conductivity
on characteristic length of gas film were newly analyzed. Factors of YK model
were modified in present work and validated through comparison with
experimental data from previous literature.Comment: 8 figure
Percolation transitions with nonlocal constraint
We investigate percolation transitions in a nonlocal network model
numerically. In this model, each node has an exclusive partner and a link is
forbidden between two nodes whose -neighbors share any exclusive pair. The
-neighbor of a node is defined as a set of at most neighbors of
, where is the total number of nodes. The parameter controls the
strength of a nonlocal effect. The system is found to undergo a percolation
transition belonging to the mean field universality class for . On the
other hand, for , the system undergoes a peculiar phase transition from
a non-percolating phase to a quasi-critical phase where the largest cluster
size scales as with . In the
marginal case with , the model displays a percolation transition that
does not belong to the mean field universality class.Comment: 4 pages, 5 figure
Epidemic Threshold of Susceptible-Infected-Susceptible Model on Complex Networks
We demonstrate that the susceptible-infected-susceptible (SIS) model on
complex networks can have an inactive Griffiths phase characterized by a slow
relaxation dynamics. It contrasts with the mean field theoretical prediction
that the SIS model on complex networks is active at any nonzero infection rate.
The dynamic fluctuation of infected nodes, ignored in the mean field approach,
is responsible for the inactive phase. It is proposed that the question whether
the epidemic threshold of the SIS model on complex networks is zero or not can
be resolved by the percolation threshold in a model where nodes are occupied in
the degree-descending order. Our arguments are supported by the numerical
studies on scale-free network models.Comment: 5 pages, 4 figure
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