13,011 research outputs found
Non-equilibrium ionization around clouds evaporating in the interstellar medium
It is of prime importance for global models of the interstellar medium to know whether dense clouds do or do not evaporate in the hot coronal gas. The rate of mass exchanges between phases depends very much on that. McKee and Ostriker's model, for instance, assumes that evaporation is important enough to control the expansion of supernova remnants, and that mass loss obeys the law derived by Cowie and McKee. In fact, the geometry of the magnetic field is nearly unknown, and it might totally inhibit evaporation, if the clouds are not regularly connected to the hot gas. Up to now, the only test of the theory is the U.V. observation (by the Copernicus and IUE satellites) of absorption lines of ions such as OVI or NV, that exist at temperatures of a few 100,000 K typical of transition layers around evaporating clouds. Other means of testing the theory are discussed
Neutrino Masses in Split Supersymmetry
We investigate the possibility to generate neutrino masses in the context of
Split supersymmetric scenarios where all sfermions are very heavy. All relevant
contributions coming from the R-parity violating terms to the neutrino mass
matrix up to one-loop level are computed, showing the importance of the Higgs
one-loop corrections. We conclude that it is not possible to generate all
neutrino masses and mixings in Split SUSY with bilinear R-Parity violating
interactions. In the case of Partial Split SUSY the one-loop Higgs
contributions are enough to generate the neutrino masses and mixings in
agreement with the experiment. In the context of minimal SUSY SU(5) we find new
contributions which help us to generate neutrino masses in the case of Split
SUSY.Comment: 33 pages, 6 figures, to appear in Physical Review
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