5,799 research outputs found
The quantum free particle on spherical and hyperbolic spaces: A curvature dependent approach
The quantum free particle on the sphere () and on the
hyperbolic plane () is studied using a formalism that
considers the curvature \k as a parameter. The first part is mainly concerned
with the analysis of some geometric formalisms appropriate for the description
of the dynamics on the spaces (, \IR^2, ) and with
the the transition from the classical -dependent system to the quantum
one using the quantization of the Noether momenta. The Schr\"odinger
separability and the quantum superintegrability are also discussed. The second
part is devoted to the resolution of the -dependent Schr\"odinger
equation. First the characterization of the -dependent `curved' plane
waves is analyzed and then the specific properties of the spherical case are
studied with great detail. It is proved that if then a discrete
spectrum is obtained. The wavefunctions, that are related with a
-dependent family of orthogonal polynomials, are explicitly obtained
RPA puzzle in C(12) weak decay processes
We explain the origin of the difficulties that appear in a straightforward
application of the QRPA in C(12), and we demonstrate that it is imperative to
use the projected QRPA (PQRPA). Satisfactory results, not only for the weak
processes among the ground states of the triad B(12),C(12),N(12), but also for
the inclusive ones are obtained. We sketch as well a new formalism for the
neutrino-nucleus interaction that furnishes very simple final formulae for the
muon capture rate and neutrino induced cross sections.Comment: 14 pages in LaTex, changes are included in the text, to appear in PL
Quantization of Hamiltonian systems with a position dependent mass: Killing vector fields and Noether momenta approach
The quantization of systems with a position dependent mass (PDM) is studied.
We present a method that starts with the study of the existence of Killing
vector fields for the PDM geodesic motion (Lagrangian with a PDM kinetic term
but without any potential) and the construction of the associated Noether
momenta. Then the method considers, as the appropriate Hilbert space, the space
of functions that are square integrable with respect to a measure related with
the PDM and, after that, it establishes the quantization, not of the canonical
momenta , but of the Noether momenta instead. The quantum Hamiltonian,
that depends on the Noether momenta, is obtained as an Hermitian operator
defined on the PDM Hilbert space. In the second part several systems with
position-dependent mass, most of them related with nonlinear oscillators, are
quantized by making use of the method proposed in the first part.Comment: 21 pages, to appear in J.Phys. A:Math. Theo
Study of the average vertical distribution of temperature in the martian atmosphere final report
Convective-radiative equilibrium model for computing temperature profile - vertical temperature distribution in Martian atmospher
Relic density calculations beyond tree-level, exact calculations versus effective couplings: the ZZ final state
The inferred value of the relic density from cosmological observations has
reached a precision that is akin to that of the LEP precision measurements.
This level of precision calls for the evaluation of the annihilation cross
sections of dark matter that goes beyond tree-level calculations as currently
implemented in all codes for the computation of the relic density. In
supersymmetry radiative corrections are known to be large and thus must be
implemented. Full one-loop radiative corrections for many annihilation
processes have been performed. It is important to investigate whether the bulk
of these corrections can be parameterised through an improved Born
approximation that can be implemented as a selection of form factors to a
tree-level code. This paper is a second in a series that addresses this issue.
After having provided these form factors for the annihilation of the
neutralinos into fermions, which cover the case of a bino-like LSP (Lightest
Supersymmetric Particle), we turn our attention here to a higgsino-like dark
matter candidate through its annihilation into . We also investigate the
cases of a mixed LSP. In all cases we compare the performance of the form
factor approach with the result of a full one-loop correction. We also study
the issue of the renormalisation scheme dependence. An illustration of the
phenomenon of non decoupling of the heavy sfermions that takes place for the
annihilation of the lightest neutralino into is also presented.Comment: 20
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