2,330 research outputs found
Constraints on mass matrices due to measured property of the mixing matrix
It is shown that two specific properties of the unitary matrix can be
expressed directly in terms of the matrix elements and eigenvalues of the
hermitian matrix which is diagonalized by . These are the asymmetry
, of with respect to the main diagonal
and the Jarlskog invariant .
These expressions for and provide constraints on possible
mass matrices from the available data on .Comment: 5 pages, Late
Single and Pair Production of Doubly Charged Higgs Bosons at Hadron Colliders
Current searches for doubly charged Higgs bosons (H^{\pm\pm}) at the Fermilab
Tevatron are sensitive to single production of H^{\pm\pm}, although the pair
production mechanism q\bar q\to H^{++}H^{--} is assumed to be dominant. In the
context of a Higgs Triplet Model we study the mechanism q'\bar q\to
H^{\pm\pm}H^{\mp} at the Tevatron and CERN Large Hadron Collider, and show that
its inclusion can significantly improve the search potential for H^{\pm\pm}.
Moreover, assuming that the neutrino mass is generated solely by the triplet
field Yukawa coupling to leptons, we compare the branching ratios of
H^{\pm\pm}\to l^\pm l^\pm and H^{\pm\pm}\to H^\pm W^* for the cases of a normal
hierarchical, inverted hierarchical and degenerate neutrino mass spectrum.Comment: 17 pages, 15 figures, references added, version to appear in PR
Constraints from Neutrinoless Double Beta Decay
We examine the constraints from the recent HEIDELBERG-MOSCOW double beta
decay experiment. It leads us to the almost degenerate or inverse hierarchy
neutrino mass scenario. In this scenario, we obtain possible upper bounds for
the Majorana CP violating phase in the lepton sector by incorporating the data
from the neutrino oscillation, the single beta decay experiments, and from the
astrophysical observation. We also predict the neutrino mass that may be
measurable in the future beta decay experiments.Comment: 10 pages, 3 figure
Another possible way to determine the Neutrino Mass Hierarchy
We show that by combining high precision measurements of the atmospheric
delta m^2 in both the electron and muon neutrino (or anti-neutrino)
disappearance channels one can determine the neutrino mass hierarchy. The
required precision is a very challenging fraction of one per cent for both
measurements. At even higher precision, sensitivity to the cosine of the CP
violating phase is also possible. This method for determining the mass
hierarchy of the neutrino sector does not depend on matter effects.Comment: 12 pages, 3 postscript figures, late
CP violation in neutrino oscillation and leptogenesis
We study the correlation between CP violation in neutrino oscillations and
leptogenesis in the framework with two heavy Majorana neutrinos and three light
neutrinos. Among three unremovable CP phases, a heavy Majorana phase
contributes to leptogenesis. We show how the heavy Majorana phase contributes
to Jarlskog determinant as well as neutrinoless double decay by
identifying a low energy CP violating phase which signals the CP violating
phase for leptogenesis. For some specific cases of the Dirac mass term of
neutrinos, a direct relation between lepton number asymmetry and is
obtained. For the most general case of the framework, we study the effect on coming from the phases which are not related to leptogenesis, and also show
how the correlation can be lost in the presence of those phases.Comment: 4 pages and 3 figure
Neutrinoless Double Beta Decay and Future Neutrino Oscillation Precision Experiments
We discuss to what extent future precision measurements of neutrino mixing
observables will influence the information we can draw from a measurement of
(or an improved limit on) neutrinoless double beta decay. Whereas the Delta m^2
corresponding to solar and atmospheric neutrino oscillations are expected to be
known with good precision, the parameter theta_{12} will govern large part of
the uncertainty. We focus in particular on the possibility of distinguishing
the neutrino mass hierarchies and on setting a limit on the neutrino mass. We
give the largest allowed values of the neutrino masses which allow to
distinguish the normal from the inverted hierarchy. All aspects are discussed
as a function of the uncertainty stemming from the involved nuclear matrix
elements. The implications of a vanishing, or extremely small, effective mass
are also investigated. By giving a large list of possible neutrino mass
matrices and their predictions for the observables, we finally explore how a
measurement of (or an improved limit on) neutrinoless double beta decay can
help to identify the neutrino mass matrix if more precise values of the
relevant parameters are known.Comment: 35 pages, 12 figures. Comments and references added. To appear in PR
Relation between the neutrino and quark mixing angles and grand unification
We argue that there exists simple relation between the quark and lepton
mixings which supports the idea of grand unification and probes the underlying
robust bi-maximal fermion mixing structure of still unknown flavor physics. In
this framework the quark mixing matrix is a parameter matrix describing the
deviation of neutrino mixing from exactly bi-maximal, predicting
theta_{sol}+theta_C=pi/4, where theta_C is the Cabibbo angle,
theta_{atm}+theta_{23}^{CKM}=pi/4 and theta_{13}^{MNS} ~ theta_{13}^{CKM} ~
O(lambda^3), in a perfect agreement with experimental data. Both non-Abelian
and Abelian flavor symmetries are needed for such a prediction to be realistic.
An example flavor model capable to explain this flavor mixing pattern, and to
induce the measured quark and lepton masses, is outlined.Comment: references added, title changed in journa
The small mixing angle and the lepton asymmetry
We present the correlation of low energy CP phases, both Dirac and Majorana,
and the lepton asymmetry for the baryon asymmetry in the universe, with a
certain class of Yukawa matrices that consist of two right-handed neutrinos and
include one texture zero in themselves. For cases in which the amount of the
lepton asymmetry turns out to be proportional to , we
consider the relation between two types of CP phases and the relation of
versus the Jarlskog invariant or the amplitude of neutrinoless double beta
decay as varies.Comment: 17 pages, 14 figures, information for figures added, version
published in PR
Large Lepton Mixing and Nonsymmetric Mass Matrices with Flavor 2 <-> 3 Symmetry
We analyze the lepton sector of a recently proposed nonsymmetric mass matrix
model. Our model gives a unified description of quark and lepton with the same
texture form based on an extended flavor symmetry with a
phase. By investigating possible types of assignment for masses, we find that
the model can lead to large lepton mixings which are consistent with
experimental values. We also find that the model predicts a very small value,
, for the lepton mixing matrix element square .
The CP violating phases in the lepton mixing matrix and a suppression of the
averaged neutrino mass in the neutrinoless double beta decay are also
predicted.Comment: 15pages, 2figure
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