arXiv subjects

A. Samana

Publications and source records attributed to A. Samana.

3 recordsLinked to original sources

arXiv2006

A Reanalysis of the LSND Neutrino Oscillation Experiment

We reanalyse the LSND neutrino oscillation results in the framework of the Projected Quasiparticle Random Phase Approximation (PQRPA), which is the only RPA model that treats the Pauli Principle correctly, and accounts satisfactorily for great majority of the weak decay observables around 12C. We have found that the employment of the PQRPA inclusive DIF 12C(nu_e,e-)12N cross-section, instead of the CRPA used by the LSND collaboration in the (nu_mu ->nu_e) oscillations study of the 1993-1995 data sample, leads to the following: 1) the oscillation probability is increased from (0.26 +/- 0.10 +/- 0.05) percents to (0.33 +/- 0.10 +/- 0.13) percents, and 2) the previously found consistence between the (sin^2 2theta, Delta m^2) confidence level regions for the (nu_mu -> nu_e) and the (bar{nu}_mu -> bar{nu}_e) oscillations is significantly diminished. These effects are not due to the difference in the uncertainty ranges for the neutrino-nucleus cross-section, but to the difference in the cross-sections themselves.

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arXiv2005

Neutrino-Nucleus Reactions and Muon Capture in 12C

The neutrino-nucleus cross section and the muon capture rate are discussed within a simple formalism which facilitates the nuclear structure calculations. The corresponding formulae only depend on four types of nuclear matrix elements, which are currently used in the nuclear beta decay. We have also considered the non-locality effects arising from the velocity-dependent terms in the hadronic current. We show that for both observables in 12C the higher order relativistic corrections are of the order of ~5 only, and therefore do not play a significant role. As nuclear model framework we use the projected QRPA (PQRPA) and show that the number projection plays a crucial role in removing the degeneracy between the proton-neutron two quasiparticle states at the level of the mean field. Comparison is done with both the experimental data and the previous shell model calculations. Possible consequences of the present study on the determination of the $ν_μ->ν_e$ neutrino oscillation probability are briefly addressed.

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arXiv2002

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.

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