63,704 research outputs found
Constraining and Dark Energy with Gamma-Ray Bursts
An relationship with a small
scatter for current -ray burst (GRB) data was recently reported, where
is the beaming-corrected -ray energy and
is the peak energy in the local observer frame. By considering this
relationship for a sample of 12 GRBs with known redshift, peak energy, and
break time of afterglow light curves, we constrain the mass density of the
universe and the nature of dark energy. We find that the mass density
(at the confident level) for a flat
universe with a cosmological constant, and the parameter of an assumed
static dark-energy equation of state ().
Our results are consistent with those from type Ia supernovae. A larger sample
established by the upcoming {\em Swift} satellite is expected to provide
further constraints.Comment: 8 pages including 4 figures, to appear in ApJ Letters, typos
correcte
Breaking of the overall permutation symmetry in nonlinear optical susceptibilities of one-dimensional periodic dimerized Huckel model
Based on infinite one-dimensional single-electron periodic models of
trans-polyacetylene, we show analytically that the overall permutation symmetry
of nonlinear optical susceptibilities is, albeit preserved in the molecular
systems with only bound states, no longer generally held for the periodic
systems. The overall permutation symmetry breakdown provides a fairly natural
explanation to the widely observed large deviations of Kleinman symmetry for
periodic systems in off-resonant regions. Physical conditions to experimentally
test the overall permutation symmetry break are discussed.Comment: 7 pages, 1 figur
Quakes in Solid Quark Stars
A starquake mechanism for pulsar glitches is developed in the solid quark
star model. It is found that the general glitch natures (i.e., the glitch
amplitudes and the time intervals) could be reproduced if solid quark matter,
with high baryon density but low temperature, has properties of shear modulus
\mu = 10^{30~34} erg/cm^3 and critical stress \sigma_c = 10^{18~24} erg/cm^3.
The post-glitch behavior may represent a kind of damped oscillations.Comment: 11 pages, 4 figures (but Fig.3 is lost), a complete version can be
obtained by http://vega.bac.pku.edu.cn/~rxxu/publications/index_P.htm, a new
version to be published on Astroparticle Physic
A coordination game model for risk allocation of a PPP project with the weakened hedged probabilistic linguistic term information
Risk allocation is a considerable part of public-private partnership
(PPP) projects’ achievement during risk management. Regarding
the complication of PPP projects, the difficulty of risk management,
and the incomplete information of the project, it may be
complicated to allocate risk factors with numbers, which may
cause players’ hesitations, the poor performance of strategies, and
the complexity of risk allocation process. To display the dynamic
and the objective of risk allocation strategies, players prefer to
take linguistic variables to depict their strategies. In this paper,
we take the linguistic expression, the probabilistic linguistic terms
with weakened hedges (P-LTWHs) to express players’ strategies.
The P-LTWHs not only take the hedges of linguistic variables but
also consider the probabilities of choosing the corresponding linguistic
variables. With the perspective of viewpoints dynamics, we
developed risk allocation models of the market risk with coordination
game under the P-LTWHs environment. Finally, we give
some suggestions of risk allocation models with P-LTWHs
information
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