26,506 research outputs found
Recent experimental data and the size of the quark in the Constituent Quark Model
We use the Constituent Quark Model (CQM) to describe CDF data on double
parton cross section and HERA data on the 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, , in accordance with the assumption on which CQM is based.Comment: 21 pages, 19 figure
Three charged particles in the continuum. Astrophysical examples
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 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 which take place as a step of
-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
We show, in complete accord with the usual Rindler picture, that detectors
with constant acceleration in de Sitter (dS) and Anti de Sitter (AdS)
spaces with cosmological constants measure temperatures , the detector "5-acceleration" in the
embedding flat 5-space. For dS, this recovers a known result; in AdS, where
is negative, the temperature is well defined down to the critical
value , 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
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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