646 research outputs found
Non-extensive resonant reaction rates in astrophysical plasmas
We study two different physical scenarios of thermonuclear reactions in
stellar plasmas proceeding through a narrow resonance at low energy or through
the low energy wing of a wide resonance at high energy. Correspondingly, we
derive two approximate analytical formulae in order to calculate thermonuclear
resonant reaction rates inside very coupled and non ideal astrophysical plasmas
in which non-extensive effects are likely to arise. Our results are presented
as simple first order corrective factors that generalize the well known
classical rates obtained in the framework of Maxwell-Boltzmann statistical
mechanics. As a possible application of our results, we calculate the
dependence of the total corrective factor with respect to the energy at which
the resonance is located, in an extremely dense and non ideal carbon plasma.Comment: 5 pages, 1 figur
Full separability criterion for tripartite quantum systems
In this paper, an intuitive approach is employed to generalize the full
separability criterion of tripartite quantum states of qubits to the
higher-dimensional systems (Phys. Rev. A \textbf{72}, 022333 (2005)). A
distinct characteristic of the present generalization is that less restrictive
conditions are needed to characterize the properties of full separability.
Furthermore, the formulation for pure states can be conveniently extended to
the case of mixed states by utilizing the kronecker product approximate
technique. As applications, we give the analytic approximation of the criterion
for weakly mixed tripartite quantum states and investigate the full
separability of some weakly mixed states.Comment: 5 pages. To be published in Europ. J.
Evolution of coupled fermions under the influence of an external axial-vector field
The evolution of coupled fermions interacting with external axial-vector
fields is described with help of the classical field theory. We formulate the
initial conditions problem for the system of two coupled fermions in
(3+1)-dimensional space-time. This problem is solved using the perturbation
theory. We obtain in the explicit form the expressions for the leading and next
to the leading order terms in the expansion over the strength of external
fields. It is shown that in the relativistic limit the intensity of the fermion
field coincides with the transition probability in the two neutrinos system
interacting with moving and polarized matter.Comment: RevTeX4, 8 pages, 1 eps figure; revised variant, neutral currents
interactions of flavor neutrinos are included, some typos corrected, 1
reference added; accepted for publication in Eur.Phys.J.
Service organizations, applying SAS no. 70, as amended with conforming changes as of May 1, 2009; Audit and accounting guide
https://egrove.olemiss.edu/aicpa_indev/2062/thumbnail.jp
Service organizations, applying SAS no. 70, as amended with conforming changes as of May 1, 2006; Audit guide: Service organi
https://egrove.olemiss.edu/aicpa_indev/1606/thumbnail.jp
Service organizations, applying SAS no. 70, as amended with conforming changes as of March 1, 2008; Audit and accounting guide
https://egrove.olemiss.edu/aicpa_indev/2061/thumbnail.jp
Flavor changing neutral currents from lepton and B decays in the two Higgs doublet model
Constraints on the whole spectrum of lepton flavor violating vertices are
shown in the context of the standard two Higgs doublet model. The vertex
involving the mixing is much more constrained than the others, and
the decays proportional to such vertex are usually very supressed. On the other
hand, bounds on the quark sector are obtained from leptonic decays of the
mesons and from . We emphasize that
although the mixing restricts severely the
mixing vertex, the upper bound for this vertex could still give a sizeable
contribution to the decay respect to the standard
model contribution, from which we see that such vertex could still play a role
in the phenomenology.Comment: 9 pages, 2 figures, LaTeX2e. Minor typos corrected. References added
and corrected. Introduction change
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