Leptonic Generation Mixing, Noncommutative Geometry and Solar Neutrino Fluxes

Triangular mass matrices for neutrinos and their charged partners contain full information on neutrino mixing in a most concise form. Although the scheme is general and model independent, triangular matrices are typical for reducible but indecomposable representations of graded Lie algebras which, in turn, are characteristic for the standard model in noncommutative geometry. The mixing matrix responsible for neutrino oscillations is worked out analytically for two and three lepton families. The example of two families fixes the mixing angle to just about what is required by the Mikheyev-Smirnov-Wolfenstein resonance oscillation of solar neutrinos. In the case of three families we classify all physically plausible choices for the neutrino mass matrix and derive interesting bounds on some of the moduli of the mixing matrix.Comment: LaTeX, 12 page

Shadows and Light

in the evening winter is creme among shadows, belting mysteriously to grass and thinly-clad trees..

Escape Artist

It was a small place, and smelled of onions thinly veiled by cigarette smoke. Olivia Bernard sat in a corner booth, toying with a half-empty glass of Mateus rose..

Do nuclei go pear-shaped? Coulomb excitation 220Rn and 224Ra at REXISOLDE (CERN)

Artículo escrito por muchos autores, sólo se referencian el primero, los autores que firman como Universidad Autónoma de Madrid y el grupo de colaboración en el caso de que aparezca en el artículoThe IS475 collaboration conducted Coulomb-excitation experiments with post-accelerated radioactive 220Rn and 224Ra beams at the REX-ISOLDE facility. The beam particles (Ebeam: 2.83 MeV/u) were Coulomb excited using 60Ni, 114Cd, and 120Sn scattering targets. De-excitation γ-rays were detected employing the Miniball array and scattered particles were detected in a silicon detector. Exploiting the Coulomb-excitation code GOSIA for each nucleus several matrix elements could be obtained from the measured γ-ray yields. The extracted {3-∥E3∥0+} matrix element allows for the conclusion that, while 220Rn represents an octupole vibrational system, 224Ra has already substantial octupole correlations in its ground state. This finding has implications for the search of CP-violating Schiff moments in the atomic systems of the adjacent odd-mass nucleiThis work was supported by the following Research Councils: STFC (UK), BMBF (Germany; 05P12RDCIA, 06DA9036I, 06KY9136I and 06KY205I), HIC for FAIR (Germany), FWO-Vlaanderen (Belgium), Belgian Science Policy Office (IAP-BriX network P7/12), Academy of Finland (contract no. 131665), DOE (US; DE-AC52-07NA27344 and DEFG02- 04ER41331), NSF (US), MICINN (Spain; FPA2009-08958 and FIS2009-07277), Consolider-Ingenio 2010 Programmes (Spain; CPAN CSD2007-00042 and MULTIDARK CSD2009-00064), Polish Ministry for Science and Higher Education (grant no. 589/N-G-POOL/2009/0), EC via I3-EURONS (FP6 contract no. RII3-CT-2004-506065), MC Fellowship scheme (FP7 contract PIEF-GA-2008-219175) and IAENSAR (FP7 contract 262010

Supersymmetric Contributions to Weak Decay Correlation Coefficients

We study supersymmetric contributions to correlation coefficients that characterize the spectral shape and angular distribution for polarized muon- and beta-decays. In the minimal supersymmetric Standard Model (MSSM), one-loop box graphs containing superpartners can give rise to non-(V-A)x(V-A) four fermion operators in the presence of left-right or flavor mixing between sfermions. We analyze the present phenomenological constraints on such mixing and determine the range of allowed contributions to the weak decay correlation coefficients. We discuss the prospective implications for future muon- and beta-decay experiments, and argue that they may provide unique probes of left-right mixing in the first generation scalar fermion sector.Comment: Revised version - to appear in Phys.Rev.

Home, head direction stability, and grid cell distortion

The home is a unique location in the life of humans and animals. In rats, home presents itself as a multicompartmental space that involves integrating navigation through subspaces. Here we embedded the laboratory rat’s home cage in the arena, while recording neurons in the animal’s parasubiculum and medial entorhinal cortex, two brain areas encoding the animal’s location and head direction. We found that head direction signals were unaffected by home cage presence or translocation. Head direction cells remain globally stable and have similar properties inside and outside the embedded home. We did not observe egocentric bearing encoding of the home cage. However, grid cells were distorted in the presence of the home cage. While they did not globally remap, single firing fields were translocated toward the home. These effects appeared to be geometrical in nature rather than a home-specific distortion and were not dependent on explicit behavioral use of the home cage during a hoarding task. Our work suggests that medial entorhinal cortex and parasubiculum do not remap after embedding the home, but local changes in grid cell activity overrepresent the embedded space location and might contribute to navigation in complex environments