27,320 research outputs found

    Recent experimental data and the size of the quark in the Constituent Quark Model

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    We use the Constituent Quark Model (CQM) to describe CDF data on double parton cross section and HERA data on the J/Ψ J / \Psi ratio cross section of elastic and inelastic diffractive productions. Our estimate shows that the radius of the constituent quark turns out to be rather small, Rquark2≈0.1Gev−2R^2_{quark} \approx 0.1 Gev^{-2}, in accordance with the assumption on which CQM is based.Comment: 21 pages, 19 figure

    Three charged particles in the continuum. Astrophysical examples

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    We suggest a new adiabatic approach for description of three charged particles in the continuum. This approach is based on the Coulomb-Fourier transformation (CFT) of three body Hamiltonian, which allows to develop a scheme, alternative to Born-Oppenheimer one. The approach appears as an expansion of the kernels of corresponding integral transformations in terms of small mass-ratio parameter. To be specific, the results are presented for the system ppeppe in the continuum. The wave function of a such system is compared with that one which is used for estimation of the rate for triple reaction p+p+e→d+ν, p+p+e\to d+\nu, which take place as a step of pppp-cycle in the center of the Sun. The problem of microscopic screening for this particular reaction is discussed

    Accelerated Detectors and Temperature in (Anti) de Sitter Spaces

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    We show, in complete accord with the usual Rindler picture, that detectors with constant acceleration aa in de Sitter (dS) and Anti de Sitter (AdS) spaces with cosmological constants Λ\Lambda measure temperatures 2πT=(Λ/3+a2)1/2≡a52\pi T=(\Lambda/3+a^{2})^{1/2}\equiv a_{5}, the detector "5-acceleration" in the embedding flat 5-space. For dS, this recovers a known result; in AdS, where Λ\Lambda is negative, the temperature is well defined down to the critical value a5=0a_{5}=0, again in accord with the underlying kinematics. The existence of a thermal spectrum is also demonstrated for a variety of candidate wave functions in AdS backgrounds.Comment: Latex +2 Fi

    Coulomb gap in the one-particle density of states in three-dimensional systems with localized electrons

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    The one-particle density of states (1P-DOS) in a system with localized electron states vanishes at the Fermi level due to the Coulomb interaction between electrons. Derivation of the Coulomb gap uses stability criteria of the ground state. The simplest criterion is based on the excitonic interaction of an electron and a hole and leads to a quadratic 1P-DOS in the three-dimensional (3D) case. In 3D, higher stability criteria, including two or more electrons, were predicted to exponentially deplete the 1P-DOS at energies close enough to the Fermi level. In this paper we show that there is a range of intermediate energies where this depletion is strongly compensated by the excitonic interaction between single-particle excitations, so that the crossover from quadratic to exponential behavior of the 1P-DOS is retarded. This is one of the reasons why such exponential depletion was never seen in computer simulations.Comment: 6 pages, 1 figur
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