Modelling electron interactions: a semi-rigorous method

We report total electron scattering cross sections (TCS) for SF6, SF5 CF3, and CF3I, molecules of interest to the plasma industry over the energy range from threshold to 2000 eV. We also report the total scattering cross sections for e-formaldehyde for which there are currently no theoretical or experimental results reported. The ionization cross sections for these targets are also estimated using the Deustch and Maerk formalism and are compared with Binary Encounter Bethe (BEB) data of Kim

New model for the neutrino mass matrix

I suggest a model based on a softly broken symmetry L_e - L_mu - L_tau and on Babu's mechanism for two-loops radiative generation of the neutrino masses. The model predicts that one of the physical neutrinos (nu_3) is massless and that its component along the nu_e direction (U_e3) is zero. Moreover, if the soft-breaking term is assumed to be very small, then the vacuum oscillations of nu_e have almost maximal amplitude and solve the solar-neutrino problem. New scalars are predicted in the 10 TeV energy range, and a breakdown of e-mu-tau universality should not be far from existing experimental bounds.Comment: 7 pages including 3 figure

Numerical consistency check between two approaches to radiative corrections for neutrino masses and mixings

We briefly outline the two popular approaches on radiative corrections to neutrino masses and mixing angles, and then carry out a detailed numerical analysis for a consistency check between them in MSSM. We find that the two approaches are nearly consistent with a small discrepancy of a factor of 13 percent in mass eigenvalues at low energy scale, but the predictions on mixing angles are almost consistent. We check the stability of the three types of neutrino models, i.e., hierarchical, inverted hierarchical and degenerate models, under radiative corrections, using both approaches, and find consistent conclusions. The neutrino mass models which are found to be stable under radiative corrections in MSSM are the normal hierarchical model and the inverted hierarchical model with opposite CP parity. We also carry out numerical analysis on some important conjectures related to radiative corrections in MSSM, viz., radiative magnification of solar and atmospheric mixings in case of nearly degenerate model having same CP parity (MPR conjecture) and radiative generation of solar mass scale in exactly two-fold degenerate model with opposite CP parity and non-zero reactor angle (JM conjecture). We observe certain exceptions to these conjectures. Finally the effect of scale-dependent vacuum expectation value in neutrino mass renormalisation is discussed.Comment: 26 pages, 5 figures,references added, typos corrected and text modifie

Relating Leptogenesis to Low Energy Flavor Violating Observables in Models with Spontaneous CP Violation

In the minimal left-right symmetric model, there are only two intrinsic CP violating phases to account for all CP violation in both the quark and lepton sectors, if CP is broken spontaneously by the complex phases in the VEV's of the scalar fields. In addition, the left- and right-handed Majorana mass terms for the neutrinos are proportional to each other due to the parity in the model. This is thus a very constrained framework, making the existence of correlations among the CP violation in leptogenesis, neutrino oscillation and neutrinoless double beta decay possible. In these models, CP violation in the leptonic sector and CP violation in the quark sector are also related. We find, however, that such connection is rather weak due to the large hierarchy in the bi-doublet VEV required by a realistic quark sector.Comment: RevTeX4, 21 pages; v2: references added, version to appear in Phys. Rev.

Sneutrino Vacuum Expectation Values and Neutrino Anomalies Through Trilinear R-parity Violation

Neutrino mass spectrum is reanalyzed in supersymmetric models with explicit trilinear $R$ violation. Models in this category are argued to provide simultaneous solution to the solar and atmospheric neutrino anomalies. It is shown specifically that large mixing and hierarchical masses needed for the vacuum solution of neutrino anomalies arise naturally in these models without requiring any additional symmetries or hierarchies among the trilinear couplings.Comment: References added and typos correcte

Neutrino Anomalies in Gauge Mediated Model with Trilinear R violation

The structure of neutrino masses and mixing resulting from trilinear $R$ violating interactions is studied in the presence of the gauge mediated supersymmetry breaking. Neutrino masses arise in this model at tree level through the RG-induced vacuum expectation values of the sneutrinos and also through direct contribution at 1-loop. The relative importance of these contributions is determined by the values of the strong and weak coupling constants. In case of purely $\lambda'$ couplings, the tree contribution dominates over the 1-loop diagram. In this case, one simultaneously obtains atmospheric neutrino oscillations and quasi-vacuum oscillations of the solar neutrinos if all the \l' couplings are assumed to be of similar magnitudes. If R parity violation arises from the trilinear \l couplings, then the loop induced contribution dominates over the tree level. One cannot simultaneously explain the solar and atmospheric deficit in this case if all the \l couplings are of similar magnitude. This however becomes possible with hierarchical \l and we give a specific example of this.Comment: 26 pages Latex, 2 figures, certain sections rewritten, improved discussion about derivations added. To appear in Physical Review