The interactions of fermions with the domain-wall produced during a first-order phase transition are considered. An exact solution of the Dirac equation's fermion propagation is obtained for a wall ...profile incorporating a position-dependent CP-violating phase. The reflection coefficients through the wall are computed for particles and antiparticles. The asymmetry in the reflection coefficients is especially high (a resonance effect) when the energy and mass of the incident particles are E/m={delta}{theta}/2, where {delta}{theta} is the phase variation across the wall width. We compute 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 {rho}B/s {approx} 10{sup -10} for a large of parameters and CP violation. As a function of {delta}{theta}, the ratio {rho}b/s reaches a maximum for large values of {delta}{theta} (m {approx} m{sub top})
An updated analysis of all available neutrino oscillation evidence in Solar experiments including the latest SNO data is presented. Predictions for total rates and day–night asymmetry in Borexino are ...calculated. Our analysis features the use of exhaustive computation of the neutrino oscillation probabilities and of an improved statistical
χ
2 treatment.
In the framework of two neutrino oscillations we conclude that the best fit to the data is obtained in the LMA region with parameters
(Δm
2,
tan
2θ)=(5.4×10
−5
eV
2,0.38)
, (
χ
2
min/
n=0.81,
n=38 degrees of freedom). Although less favored, solutions in the LOW and VAC regions are still possible with a reasonable statistical significance. The best possible solution in the SMA region gets a maximum statistical significance as low as ∼3%.
We study the implications of these results for the prospects of Borexino and the possibility of discriminating between the different solutions. The expected normalized Borexino signal is 0.63 at the best fit LMA solution, where the DN asymmetry is negligible (approximately 10
−3). In the LOW region the signal is in the range ∼0.6–0.7 at 90% confidence level while the asymmetry is ≃1–20%. As a consequence, the combined Borexino measurements of the total event rate with an error below ±5–10% and day–night total rate asymmetry with a precision comparable to the one of SuperKamiokande will have a strong chance of selecting or at least strongly favoring one of the Solar neutrino solutions provided by present data.
The complementarity between the quark and lepton mixing matrices is shown to provide a robust prediction for the neutrino mixing angle θ13PMNS. We obtain this prediction by first showing that the ...matrix VM, product of the CKM and PMNS mixing matrices, may have a zero (1,3) entry, which is favored by the experimental data. Hence models with bimaximal or tribimaximal forms of the correlation matrix VM are quite possible. Any theoretical model with a vanishing (1,3) entry of VM, which is in agreement with the quark data, and the solar and the atmospheric mixing angle leads to θ13PMNS=(9+1-2)°. This value is consistent with the present 90% CL experimental upper limit.
We consider the effect of a strongly chaotic magnetic field at the narrow bottom of the convective zone of the Sun together with resonant matter oscillations on the production of electron Majorana ...antineutrinos. Even for moderate levels of noise, we show that it is possible to obtain a small but significant probability for
ν
e→
ν
e
conversions (1–3%) at the energy range 2–10 MeV for large regions of the mixing parameter space while still satisfying present (Super)-Kamiokande antineutrino bounds and observed total rates. In the other hand it would be possible to obtain information about the solar magnetic internal field if antineutrino bounds reach the 1% level and a particle physics solution to the SNP is assumed. The mechanism presented here has the advantage of being independent of the largely unknown magnetic profile of the Sun and the intrinsic neutrino magnetic moment.
We analyze different phenomenological aspects of D-brane constructions. First, we obtain that scenarios with the gauge group and particle content of the supersymmetric standard model lead naturally ...to intermediate values for the string scale, in order to reproduce the value of gauge couplings deduced from experiments. Second, the soft terms, which turn out to be generically non-universal, and Yukawa couplings of these scenarios are studied in detail. Finally, using these soft terms and the string scale as the initial scale for their running, we compute the neutralino–nucleon cross section. In particular we find regions in the parameter space of D-brane scenarios with cross sections in the range of 10
−6–10
−5 pb, i.e., where current dark matter experiments are sensitive. For instance, this can be obtained for tan
β>5.
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