1,182 research outputs found

### Study of leptonic CP violation

The "complementary" Ansatz, Tr$(M_\nu)=0$, where $M_\nu$ is the prediagonal
neutrino mass matrix, seems a plausible approximation for capturing in a
self-contained way some of the content of Grand Unification. We study its
consequences in the form of relations between the neutrino masses and CP
violation phases.Comment: 8 pages, 1 figure, talk at MRST200

### Unified TeV Scale Picture of Baryogenesis and Dark Matter

We present a simple extension of MSSM which provides a unified picture of
cosmological baryon asymmetry and dark matter. Our model introduces a gauge
singlet field $N$ and a color triplet field $X$ which couple to the
right--handed quark fields. The out--of equilibrium decay of the Majorana
fermion $N$ mediated by the exchange of the scalar field $X$ generates adequate
baryon asymmetry for $M_N \sim 100$ GeV and $M_X \sim$ TeV. The scalar partner
of $N$ (denoted $\tilde{N}_1$) is naturally the lightest SUSY particle as it
has no gauge interactions and plays the role of dark matter. $\tilde{N}_1$
annihilates into quarks efficiently in the early universe via the exchange of
the fermionic $\tilde{X}$ field. The model is experimentally testable in (i)
neutron--antineutron oscillations with a transition time estimated to be around
$10^{10}$ sec, (ii) discovery of colored particles $X$ at LHC with mass of
order TeV, and (iii) direct dark matter detection with a predicted cross
section in the observable range.Comment: 10 pages, one reference updated. Version to appear in Phys. Rev. Let

### Leptonic CP violation in a two parameter model

We further study the "complementary" Ansatz, Tr$(M_\nu)$=0, for a prediagonal
light Majorana type neutrino mass matrix. Previously, this was studied for the
CP conserving case and the case where the two Majorana type CP violating phases
were present but the Dirac type CP violating phase was neglected. Here we
employ a simple geometric algorithm which enables us to "solve" the Ansatz
including all three CP violating phases. Specifically, given the known neutrino
oscillation data and an assumed two parameter (the third neutrino mass $m_3$
and the Dirac CP phase $\delta$) family of inputs we predict the neutrino
masses and Majorana CP phases. Despite the two parameter ambiguity, interesting
statements emerge.
There is a characteristic pattern of interconnected masses and CP phases. For
large $m_3$ the three neutrinos are approximately degenerate. The only
possibility for a mass hierarchy is to have $m_3$ smaller than the other two. A
hierarchy with $m_3$ largest is not allowed.
Small CP violation is possible only near two special values of $m_3$. Also,
the neutrinoless double beta decay parameter is approximately bounded as 0.020
eV $<|m_{ee}|<$ 0.185 eV. As a byproduct of looking at physical amplitudes we
discuss an alternative parameterization of the lepton mixing matrix which
results in simpler formulas. The physical meaning of this parameterization is
explained.Comment: 12 pages, 1 figur

### Fine structure of beta decay endpoint spectrum

We note that the fine structure at the endpoint region of the beta decay
spectrum is now essentially known using neutrino oscillation data, if the mass
of one neutrino is specified. This may help to identify the effects of nonzero
neutrino masses in future experiments. An exact treatment of phase space
kinematics is used. This work is independent of theoretical models. Additional
restrictions due to the assumption of a so-called "complementary ansatz" for
the neutrino mass matrix are also discussed.Comment: 9 pages, 8 figure

### Complementary Ansatz for the neutrino mass matrix

We propose a simple Ansatz for the three generation neutrino mass matrix
$M_\nu$ which is motivated from an SO(10) grand unified theory. The Ansatz can
be combined with information from neutrino oscillation experiments and bounds
on neutrinoless double beta decay to determine the neutrino masses themselves
and to reconstruct, with some assumptions, the matrix $M_\nu$ .Comment: 15 pages, RevteX, submitted to Phys. Rev.

### Investigating the Light Scalar Mesons

We first briefly review a treatment of the scalars in meson meson scattering
based on a non-linear chiral Lagrangian, with unitarity implemented by a
"local" modification of the scalar propagators. It is shown that the main
results are confirmed by a treatment in the SU(3) linear sigma model in which
unitarity is implemented "globally". Some remarks are made on the speculative
subject of the scalars' quark structure.Comment: 9 pages,3 figures,talk at hadron2001, Protvin

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