4 research outputs found
Validity of quasi-degenerate neutrino mass models and their predictions on baryogenesis
Quasi-degenerate neutrino mass models (QDN) which can explain the current
data on neutrino masses and mixings,are studied. In the first part, we study
the effect of CP-phases on QDN mass matrix obeying symmetry in
normal hierarchical (QD-NH) and inverted hierarchical (QD-IH) patterns.The
numerical predictions are consistent with observed data on solar mixing angle,
absolute neutrino mass parameter consistent with neutrinoless double beta decay
mass parameter and sum of three absolute neutrino masses from cosmological
bound.The neutrino mass matrix is parameterized using only two unknown
parameters. The second part deals with the estimation of observed baryon
asymmetry of the universe. The prediction is nearly consistent with observation
with flavoured thermal leptogenesis scenario. QD-NH model appears to be more
favourable than those of QD-IH models.The present analysis shows that the three
absolute neutrino masses may exhibit quasi-degenerate pattern in nature. They
are far from discrimination at the moment.Comment: 17 pages, no figure, poster presentation in the 25th International
Conference on neutrino physics and Astrophysics, Kyoto, Japan, July,201
Perturbative and Nonperturbative Contributions to a Simple Model for Baryogenesis
Single field baryogenesis, a scenario for Dirac leptogenesis sourced by a
time-dependent scalar condensate, is studied. We compare the creation of the
charge asymmetry by the perturbative decay of the condensate with the
nonperturbative decay, a process of particle production commonly known in the
context of inflation as preheating. The nonperturbative channel dominates when
the coupling of the scalar field to leptons is sufficiently large.Comment: 11 pages, 3 figure
Leptogenesis and low energy observables in left-right symmetric models
In the context of left-right symmetric models we study the connection of
leptogenesis and low energy parameters such as neutrinoless double beta decay
and leptonic CP violation. Upon imposition of a unitarity constraint, the
neutrino parameters are significantly restricted and the Majorana phases are
determined within a narrow range, depending on the kind of solar solution. One
of the Majorana phases gets determined to a good accuracy and thereby the
second phase can be probed from the results of neutrinoless double beta decay
experiments. We examine the contributions of the solar and atmospheric mass
squared differences to the asymmetry and find that in general the solar scale
dominates. In order to let the atmospheric scale dominate, some finetuning
between one of the Majorana phases and the Dirac CP phase is required. In this
case, one of the Majorana phases is determined by the amount of CP violation in
oscillation experiments.Comment: 18 pages, 6 figures. Matches version to appear in PR
One-loop QCD mass effects in the production of polarized bottom and top quarks
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