259 research outputs found
Bounds on the Solar Antineutrino total Flux and Energy spectrum from the SK experiment
A search for inverse beta decay electron antineutrinos has been carried out
using the 825 days sample of solar data obtained at SK. The absence of a
significant signal, that is, contributions to the total SK background and their
angular variations has set upper bounds on a) the absolute flux of solar
antineutrinos originated from neutrinos which is equivalent to an averaged conversion
probability bound of P<3.5% (SSM-BP98 model) and b) their differential energy
spectrum, the conversion probability is smaller than 8% for all
MeV going down the 5% level above MeV. It is shown that
an antineutrino flux would have the net effect of enhancing the SK signal at
{\em hep} neutrino energies. The magnitude of this enhancement would highly
depend on the, otherwise rather uncertain, steepness of the solar neutrino
spectrum at these energies.Comment: 5 pages, 3 ps figure
Baryon asymmetry at the weak phase transition in presence of arbitrary CP violation
We consider interactions of fermions with the domain wall bubbles produced
during a first order phase transition. A new exact solution of the Dirac
equations is obtained for a wall profile incorporating a position dependent CP
violating phase. The reflection coefficients are computed, a resonance effect
is uncovered for rapidly varying phases. This resonance effect happens when the
energy and mass of the incident particles are . Where
is the phase variation across the wall width. We calculate the
chiral charge flux through the wall surface and the corresponding baryon
asymmetry of the Universe. It agrees in sign and magnitude with the observed
baryonic excess for a large range of parameters and
CP violation. As a function of , the ratio reach a
maximum for and . PACS:
11.27.+d, 03.65.-w, 02.30.Hq, 02.30.Gp, 11.30.Fs, 98.80.CqComment: 23 pages, 7 eps figures (epsfig macro neccesary) also avalaible at
http://www-itp.unibe.ch/~torrent
KamLAND Bounds on Solar Antineutrinos and neutrino transition magnetic moments
We investigate the possibility of detecting solar electron antineutrinos with
the KamLAND experiment. These electron antineutrinos are predicted by
spin-flavor oscillations at a significant rate even if this mechanism is not
the leading solution to the SNP. KamLAND is sensitive to antineutrinos
originated from solar B neutrinos. From KamLAND negative results after
145 days of data taking, we obtain model independent limits on the total flux
of solar electron antineutrinos $\Phi({}^8 B)< 1.1-3.5\times 10^4 cm^{-2}\
s^{-1}P<0.15%\mu B< 2.3\times 10^{-21}(\Delta m^2, \tan^2\theta)\mu\lsim 3.9\times 10^{-12} \mu_BB= 50\mu\lsim 9.0\times 10^{-13} \mu_BB= 200\mu\lsim 2.0\times 10^{-13} \mu_BB= 1000$ kG at the same
statistical significance.Comment: 13 pages, 2 figure
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