Neutrino mixing in the seesaw model

In the seesaw model with hierarchical Dirac masses, the neutrino mixing angle exhibits the behavior of a narrow resonance. In general, the angle is strongly suppressed, but it can be maximal for special parameter values. We delineate the small regions in which this happens, for the two flavor problem. On the other hand, the physical neutrino masses are hierarchical, in general, except in a large part of the region in which the mixing angle is sizable, where they are nearly degenerate. Our general analysis is also applicable to the RGE of neutrino mass matrix, where we find analytic solutions for the running of physical parameters, in addition to a complex RGE invariant relating them. It is also shown that, if one mixing angle is small, the three neutrino problem reduces to two, two flavor problems.Comment: 19 pages, 4 figures; added new sections on RGE effects and universal seesaw; version to appear in EPJ

Density profiles of supernova matter and determination of neutrino parameters

The flavor conversion of supernova neutrinos can lead to observable signatures related to the unknown neutrino parameters. As one of the determinants in dictating the efficiency of resonant flavor conversion, the local density profile near the MSW resonance in a supernova environment is, however, not so well understood. In this analysis, variable power-law functions are adopted to represent the independent local density profiles near the locations of resonance. It is shown that the uncertain matter density profile in a supernova, the possible neutrino mass hierarchies, and the undetermined 1-3 mixing angle would result in six distinct scenarios in terms of the survival probabilities of $\nu_{e}$ and $\bar{\nu_{e}}$. The feasibility of probing the undetermined neutrino mass hierarchy and the 1-3 mixing angle with the supernova neutrinos is then examined using several proposed experimental observables. Given the incomplete knowledge of the supernova matter profile, the analysis is further expanded to incorporate the Earth matter effect. The possible impact due to the choice of models, which differ in the average energy and in the luminosity of neutrinos, is also addressed in the analysis.Comment: 27 pages, 10 figures. text and figures revised, references added, to appear in Phys. Rev.

THE RELATIONSHIP BETWEEN THE BARBELL TRAJECTORIES OF SNATCH AND BCH ANGLES

The purpose of this study is to investigate the relationship between the barbell trajectories of snatch and the angle between the projection vector of 7th cervical spinous process (C7) to barbell and the projection vector of C7 to hip joint in the sagittal plane (BCH angles) in different events. The ten weightlifters were divided into two groups according to their barbell trajectories (BT was categorized into the backward barbell trajectories, and the FT was forward). The results show that the BCH angles at PB and MF in BT are smaller than FT. The weightlifers with the backward trajectories usually make better performances. After analysis, we find out that the backward trajectories would reduce the BCH angles. The present study suggests that catching the bar with backward trajectories and smaller BCH angles at PB and MF are perhaps a better technique for snatch