35,045 research outputs found
Exclusive glueball production in high energy nucleus-nucleus collisions
The cross sections for the glueball candidates production in quasi-real
photon-photon collisions and on central diffraction processes, i.e. double
Pomeron exchange, in heavy ion interactions at RHIC and LHC are computed. The
rates for these distinct production channels are compared and they may be a
fruitful approach to the investigation of glueballs.Comment: 6 pages, 2 tables. Final version to be published in Physical Review
Noncommutativity due to spin
Using the Berezin-Marinov pseudoclassical formulation of spin particle we
propose a classical model of spin noncommutativity. In the nonrelativistic
case, the Poisson brackets between the coordinates are proportional to the spin
angular momentum. The quantization of the model leads to the noncommutativity
with mixed spacial and spin degrees of freedom. A modified Pauli equation,
describing a spin half particle in an external e.m. field is obtained. We show
that nonlocality caused by the spin noncommutativity depends on the spin of the
particle; for spin zero, nonlocality does not appear, for spin half, , etc. In the relativistic case the noncommutative
Dirac equation was derived. For that we introduce a new star product. The
advantage of our model is that in spite of the presence of noncommutativity and
nonlocality, it is Lorentz invariant. Also, in the quasiclassical approximation
it gives noncommutativity with a nilpotent parameter.Comment: 11 pages, references adda
Caracterização da vegetação e uso da terra da bacia Quitéria em 2007.
O objetivo deste trabalho é identificar os principais tipos de uso da terra e vegetação natural da bacia Quitéria em 2007.SBSR 2013
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