14,991 research outputs found

    A statistical mechanics framework for multi-particle production in high energy reactions

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    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

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    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

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    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

    C2C_2-cofiniteness of 2-cyclic permutation orbifold models

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    In this article, we consider permutation orbifold models of C2C_2-cofinite vertex operator algebras of CFT type. We show the C2C_2-cofiniteness of the 2-cyclic permutation orbifold model (VV)S2(V\otimes V)^{S_2} for an arbitrary C2C_2-cofinite simple vertex operator algebra VV of CFT type. We also give a proof of the C2C_2-cofiniteness of a Z2\Z_2-orbifold model VL+V_L^+ of the lattice vertex operator algebra VLV_L associated with a rank one positive definite even lattice LL by using our result and the C2C_2-cofiniteness of VLV_L.Comment: 25 pages, no figure, some typo are correcte

    Detection of weak-order phase transitions in ferromagnets by ac resistometry

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    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, Z(T)Z(T), 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 μ\mu of a sample upon the phase transition. Moreover, frequency dependence of μ\mu 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 Ni2_2MnGa.Comment: 4 pages, 2 figures, to be published in J. Appl. Phys., v.94(5

    Laboratory Experiment of Checkerboard Pupil Mask Coronagraph

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    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 10610^{-6} 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 10710^{-7} 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 2.7×1072.7 {\times} 10^{-7} and 1.1×1071.1 {\times} 10^{-7}. The coronagraphic performance significantly outperformed the 10610^{-6} 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

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    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

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    We investigate in detail the effects of the R-parity lepton number violation in the minimal supersymmetric standard model (MSSM) on the parent process ppe+e+Xpp \to e^+ e^- + X 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 e+ee^+ e^- pair production at the LHC could be significant. The results show that the cross section of the e+e e^+ e^- pair productions via gluon-gluon collision at the LHC can be of the order of 10210^2 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

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    We describe the structure of all continuous algebraic endomorphisms of the open unit ball B\mathbf{B} of R3\mathbb{R}^3 equipped with the Einstein velocity addition. We show that any nonzero such transformation originates from an orthogonal linear transformation on R3\mathbb{R}^3

    SUSY flavor structure of generic 5D supergravity models

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    We perform a comprehensive and systematic analysis of the SUSY flavor structure of generic 5D supergravity models on S1/Z2S^1/Z_2 with multiple Z2Z_2-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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