14,991 research outputs found
A statistical mechanics framework for multi-particle production in high energy reactions
We deduce the particle distributions in particle collisions with
multihadron-production in the framework of mechanical statistics. They are
derived as functions of x, P_T^2 and the rest mass of different species for a
fixed total number of all produced particles, inelasticity and total transverse
energy. For P_T larger than the mass of each particle we get the behaviour
\frac{dn_i}{dP_T} \sim \sqrt{P_T} e^{-\frac{P_T}{T_H}} Values of _\pi,
_K, and _{\bar{p}} in agreement with experiment are found by taking
T_H=180MeV (the Hagedorn temperature).Comment: 9 pages, RevTe
Validity of the second law in nonextensive quantum thermodynamics
The second law of thermodynamics in nonextensive statistical mechanics is
discussed in the quantum regime. Making use of the convexity property of the
generalized relative entropy associated with the Tsallis entropy indexed by q,
Clausius' inequality is shown to hold in the range of q between zero and two.
This restriction on the range of the entropic index, q, is purely quantum
mechanical and there exists no upper bound of q for validity of the second law
in classical theory.Comment: 12 pages, no figure
Aftershocks in Modern Perspectives: Complex Earthquake Network, Aging, and Non-Markovianity
The phenomenon of aftershocks is studied in view of science of complexity. In
particular, three different concepts are examined: (i) the complex-network
representation of seismicity, (ii) the event-event correlations, and (iii) the
effects of long-range memory. Regarding (i), it is shown the clustering
coefficient of the complex earthquake network exhibits a peculiar behavior at
and after main shocks. Regarding (ii), it is found that aftershocks experience
aging, and the associated scaling holds. And regarding (iii), the scaling
relation to be satisfied by a class of singular Markovian processes is
violated, implying the existence of the long-range memory in processes of
aftershocks.Comment: 28 pages, 6 figures and 1 table. Acta Geophysica, in pres
-cofiniteness of 2-cyclic permutation orbifold models
In this article, we consider permutation orbifold models of -cofinite
vertex operator algebras of CFT type. We show the -cofiniteness of the
2-cyclic permutation orbifold model for an arbitrary
-cofinite simple vertex operator algebra of CFT type. We also give a
proof of the -cofiniteness of a -orbifold model of the
lattice vertex operator algebra associated with a rank one positive
definite even lattice by using our result and the -cofiniteness of
.Comment: 25 pages, no figure, some typo are correcte
Detection of weak-order phase transitions in ferromagnets by ac resistometry
It is shown that ac resistometry can serve as an effective tool for the
detection of phase transitions, such as spin reorientation or premartensitic
phase transitions, which generally are not disclosed by dc resistivity
measurement. Measurement of temperature dependence of impedance, , allows
one to unmask the anomaly, corresponding to a weak-order phase transition. The
appearance of such an anomaly is accounted for by a change in the effective
permeability of a sample upon the phase transition. Moreover, frequency
dependence of makes it possible to use the frequency of the applied ac
current as an adjusting parameter in order to make this anomaly more
pronounced. The applicability of this method is tested for the rare earth Gd
and Heusler alloy NiMnGa.Comment: 4 pages, 2 figures, to be published in J. Appl. Phys., v.94(5
Laboratory Experiment of Checkerboard Pupil Mask Coronagraph
We present the results of the first laboratory experiment of checkerboard
shaped pupil binary mask coronagraphs using visible light, in the context of
the R&D activities for future mid-infrared space missions such as the 3.5 m
SPICA telescope. The primary aim of this work is to demonstrate the
coronagraphic performance of checkerboard masks down to a
peak-to-peak contrast, which is required to detect self-luminous extra-solar
planets in the mid-infrared region. Two masks, consisting of aluminum films on
a glass substrates, were manufactured using nano-fabrication techniques with
electron beam lithography: one mask was optimized for a pupil with a 30%
central obstruction and the other was for a pupil without obstruction. The
theoretical contrast for both masks was and no adaptive optics system
was employed. For both masks, the observed point spread functions were quite
consistent with the theoretical ones. The average contrast measured within the
dark regions was and . The
coronagraphic performance significantly outperformed the requirement
and almost reached the theoretical limit determined by the mask designs. We
discuss the potential application of checkerboard masks for mid-infrared
coronagraphy, and conclude that binary masks are promising for future
high-contrast space telescopes.Comment: 6 pages, 6 figure
The Ratio of W + N jets To Z/gamma + N jets As a Precision Test of the Standard Model
We suggest replacing measurements of the individual cross-sections for the
production of W + N jets and Z/gamma + N jets in searches for new high-energy
phenomena at hadron colliders by the precision measurement of the ratios (W+0
jet)/(Z+0 jet), (W+1 jet)/(Z+1 jet), (W+2 jets)/(Z+2 jets),... (W+N jets)/(Z+N
jets), with N as large as 6 (the number of jets in ttbarH). These ratios can
also be formed for the case where one or more of the jets is tagged as a b or c
quark. Existing measurements of the individual cross sections for Wenu + N jets
at the Tevatron have systematic uncertainties that grow rapidly with N, being
dominated by uncertainties in the identification of jets and the jet energy
scale. These systematics, and also those associated with the luminosity, parton
distribution functions (PDF's), detector acceptance and efficiencies, and
systematics of jet finding and b-tagging, are expected to substantially cancel
in calculating the ratio of W to Z production in each N-jet channel, allowing a
greater sensitivity to new contributions in these channels in Run II at the
Tevatron and at the LHC.Comment: 10 pages, 8 figures, added reference
Effects of the R-parity violation in the minimal supersymmetric standard model on dilepton pair production at the CERN LHC
We investigate in detail the effects of the R-parity lepton number violation
in the minimal supersymmetric standard model (MSSM) on the parent process at the CERN Large Hadron Collider (LHC). The numerical
comparisons between the contributions of the R-parity violating effects to the
parent process via the Drell-Yan subprocess and the gluon-gluon fusion are
made. We find that the R-violating effects on pair production at the
LHC could be significant. The results show that the cross section of the pair productions via gluon-gluon collision at the LHC can be of the order
of fb, and this subprocess maybe competitive with the production
mechanism via the Drell-Yan subprocess. We give also quantitatively the
analysis of the effects from both the mass of sneutrino and coupling strength
of the R-parity violating interactions.Comment: 18 pages, 10 figures, accepted by Phys. Rev.
On algebraic endomorphisms of the Einstein gyrogroup
We describe the structure of all continuous algebraic endomorphisms of the
open unit ball of equipped with the Einstein
velocity addition. We show that any nonzero such transformation originates from
an orthogonal linear transformation on
SUSY flavor structure of generic 5D supergravity models
We perform a comprehensive and systematic analysis of the SUSY flavor
structure of generic 5D supergravity models on with multiple
-odd vector multiplets that generate multiple moduli. The SUSY flavor
problem can be avoided due to contact terms in the 4D effective K\"ahler
potential peculiar to the multi-moduli case. A detailed phenomenological
analysis is provided based on an illustrative model.Comment: 37 pages, 7 figures, Sec.4 is modifie
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