396 research outputs found

    On the Mass Eigenstate Composition of the 8B Neutrinos from the Sun

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    The present data of gallium experiments provide indirectly the only experimental limit on the fraction of ν2\nu_2 mass eigenstate for the 8^8B neutrinos from the Sun. However, if to use the experimental data alone, the fraction of ν2\nu_2 and, consequently, sin2θsolsin^2\theta_{sol} still is allowed to be varied within a rather broad range. The further experimental efforts are needed to clear this point.Comment: 13 pages, 1 figure, 1 table. Corrected version, published in JCAP04(2007)00

    Hanbury Brown-Twiss interferometry and second-order correlations of inflaton quanta

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    The quantum theory of optical coherence is applied to the scrutiny of the statistical properties of the relic inflaton quanta. After adapting the description of the quantized scalar and tensor modes of the geometry to the analysis of intensity correlations, the normalized degrees of first-order and second-order coherence are computed in the concordance paradigm and are shown to encode faithfully the statistical properties of the initial quantum state. The strongly bunched curvature phonons are not only super-Poissonian but also super-chaotic. Testable inequalities are derived in the limit of large angular scales and can be physically interpreted in the light of the tenets of Hanbury Brown-Twiss interferometry. The quantum mechanical results are compared and contrasted with different situations including the one where intensity correlations are the result of a classical stochastic process. The survival of second-order correlations (not necessarily related to the purity of the initial quantum state) is addressed by defining a generalized ensemble where super-Poissonian statistics is an intrinsic property of the density matrix and turns out to be associated with finite volume effects which are expected to vanish in the thermodynamic limit.Comment: 42 pages, 3 included figures; corrected typos; to appear in Physical Review

    Deciphering nonfemtoscopic two-pion correlations in p+pp+p collisions with simple analytical models

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    A simple model of nonfemtoscopic particle correlations in proton-proton collisions is proposed. The model takes into account correlations induced by the conservation laws as well as correlations induced by minijets. It reproduces well the two-pion nonfemtoscopic correlations of like-sign and unlike-sign pions in proton-proton collision events at s=900\sqrt{s} = 900 GeV analyzed by the ALICE Collaboration. We also argue that similar nonfemtoscopic correlations can appear in the hydrodynamic picture with event-by-event fluctuating nonsymmetric initial conditions that are typically associated with nonzero higher-order flow harmonics.Comment: 21 pages, 10 figures, misprints correcte

    RC J1148+0455 identification: gravitational lens or group of galaxies ?

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    The structure of the radio source RC B1146+052 of the ``Cold'' catalogue is investigated by data of the MIT-GB-VLA survey at 4850 MHz. This source belongs to the steep spectrum radio sources subsample of the RC catalogue. Its spectral index is α\alpha = -1.04. The optical image of this source obtained with 6m telescope is analysed. The radio source center is situated in a group of 8 galaxies of about 24m^m in the R-filter. The possible explanations of the complex structure of radio components are considered.Comment: 6 pages, 5 figures, uses psfig.sty. This was the poster as presented on Gamow Memorial Internat. Conference GMIC'99 "Early Universe: Cosmological Problems and Instrumental Technologies" in St.Petersburg, 23-27 Aug., 1999. Submitted to Proceedings to be published in A&A Transaction

    Theory of plastic vortex creep

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    We develop a theory for plastic flux creep in a topologically disordered vortex solid phase in type-II superconductors. We propose a detailed description of the plastic vortex creep of the dislocated, amorphous vortex glass in terms of motion of dislocations driven by a transport current jj. The {\em plastic barriers} Upl(j)jμU_{pl}(j)\propto j^{-\mu} show power-law divergence at small drives with exponents μ=1\mu=1 for single dislocation creep and μ=2/5\mu = 2/5 for creep of dislocation bundles. The suppression of the creep rate is a hallmark of the transition from the topologically ordered vortex lattice to an amorphous vortex glass, reflecting a jump in μ\mu from μ=2/11\mu = 2/11, characterizing creep in the topologically ordered vortex lattice near the transition, to its plastic values. The lower creep rates explain the observed increase in apparent critical currents in the dislocated vortex glass.Comment: 4 pages, 1 figur

    Formation of the internal structure of solids under severe action

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    On the example of a particular problem, the theory of vacancies, a new form of kinetic equations symmetrically incorporation the internal and free energies has been derived. The dynamical nature of irreversible phenomena at formation and motion of defects (dislocations) has been analyzed by a computer experiment. The obtained particular results are extended into a thermodynamic identity involving the law of conservation of energy at interaction with an environment (the 1st law of thermodynamics) and the law of energy transformation into internal degree of freedom (relaxation). The identity is compared with the analogous Jarzynski identity. The approach is illustrated by simulation of processes during severe plastic deformation, the Rybin kinetic equation for this case has been derived.Comment: 9 pages, 5 figure

    Dynamical Pion Production via Parametric Resonance from Disoriented Chiral Condensate

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    We discuss a dynamical mechanism of pion production from disoriented chiral condensates (DCC). It leads to an explosive production of pions via the parametric amplification mechanism, which is similar to the reheating mechanism in inflationary cosmology. Classically, it is related with the instability in the solutions of the Mathieu equation and we explore the quantum aspects of the mechanism. We show that nonlinearlities and back reactions can be ignorable for sufficiently long time under the small amplitude approximations of background σ\sigma oscillations, which may be appropriate for the late stage of nonequilibrium phase transition. It allows us to obtain an explicit quantum state of the produced pions and σ\sigma, the squeezed state of BCS type. Single particle distributions and two-pion correlation functions are computed within these approximations. The results obtained illuminate the characteristic features of multi-pion states produced through the parametric amplification mechanism. In particular, two-pion correlations of various charge combinations contain back-to-back correlations which cannot be masked by the identical particle interference effect.Comment: REVTEX 18 pages and 10 figure

    Investigation of the New Local Group Galaxy VV 124

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    We present the results of our stellar photometry and spectroscopy for the new Local Group galaxy VV 124 (UGC 4879) obtained with the 6-m BTA telescope. The presence of a few bright supergiants in the galaxy indicates that the current star formation process is weak. The apparent distribution of stars with different ages in VV 124 does not differ from the analogous distributions of stars in irregular galaxies, but the ratio of the numbers of young and old stars indicates that VV 124 belongs to the rare Irr/Sph type of galaxies. The old stars (red giants) form the most extended structure, a thick disk with an exponential decrease in the star number density to the edge. Definitely, the young population unresolvable in images makes a great contribution to the background emission from the central galactic regions. The presence of young stars is also confirmed by the [O III] emission line visible in the spectra that belongs to extensive diffuse galactic regions. The mean radial velocity of several components (two bright supergiants, the unresolvable stellar population, and the diffuse gas) is v_h = -70+/-15 km/s and the velocity with which VV 124 falls into the Local Group is v_LG = -12+/-15 km/s. We confirm the distance to the galaxy D = 1.1+/-0.1 Mpc and the metallicity of red giants ([Fe/H] = -1.37) found by Kopylov et al. (2008).VV 124 is located on the periphery of the Local Group approximately at the same distance from M 31 and our Galaxy and is isolated from other galaxies. The galaxy LeoA nearest to it is 0.5 Mpc away.Comment: 10 pages, 8 figures. Accepted for publication in Astronomy Letters (2010, Vol. 36, No. 5, pp. 309-318
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