2,268 research outputs found
Natural relations among physical observables in the neutrino mass matrix
We find all possible relations among physical observables arising from
neutrino mass matrices that describe in a natural way the currently observed
pattern (tan_23 and tan_12 large, dm^2_Sun/dm^2_Atm and tan_13 small) in terms
of a minimum number of parameters. Natural here means due only to the relative
smallness (vanishing) of some parameters in the relevant lagrangian, without
special relations or accidental cancellations among them.Comment: 14 pages, 1 eps figur
Non-Universal Correction To And Flavor Changing Neutral Current Couplings
A non-universal interaction associated with top quark induces flavor changing
neutral currents (FCNC) among light fermions. The size of the FCNC effect
depends crucially on the dynamics of the fermion mass generation. In this
paper, we study the effect of a non-universal interaction on ,
{\it etc}, by using an effective lagrangian technique and assuming the quark
mass matrices in the form of a generalized Fritzsch ansatz. We point out that
if fitting to the LEP data within , the induced FCNC couplings
are very close to the experimental limits.Comment: 9 pages, Te
The Stark effect in linear potentials
We examine the Stark effect (the second-order shift in the energy spectrum
due to an external constant force) for two 1-dimensional model quantum
mechanical systems described by linear potentials, the so-called quantum
bouncer (defined by V(z) = Fz for z>0 and V(z) infinite for z<0) and the
symmetric linear potential (given by V(z) = F|z|). We show how straightforward
use of the most obvious properties of the Airy function solutions and simple
Taylor expansions give closed form results for the Stark shifts in both
systems. These exact results are then compared to other approximation
techniques, such as perturbation theory and WKB methods. These expressions add
to the small number of closed-form descriptions available for the Stark effect
in model quantum mechanical systems.Comment: 15 pages. To appear in Eur. J. Phys. Needs Institute of Physics
(iopart) style file
Large Angle MSW Solution in Grand Unified Theories with SU(3) X U(1) Horizontal Symmetry
We construct a model with a SU(3) X U(1) horizontal symmetry in the context
of Grand Unified Theories. In our models, the bi-maximal lepton mixing and
suitable neutrino masses for the large angle MSW solution are obtained without
any fine-tuning due to the spontaneously broken SU(3)_H symmetry. The three
generations of quarks and leptons are unified as members of the SU(3)_H
fundamental representation, and the U(1)_H charge gives the origin of the
fermion mass hierarchy and mixing angles. We present two explicit examples of
SU(5)_GUT and SO(10)_GUT models, in which the Yukawa structures are given
successfully.Comment: 23 pages, 6 figures, references adde
Could One Find Petroleum Using Neutrino Oscillations in Matter?
In neutrino physics, it is now widely believed that neutrino oscillations are
influenced by the presence of matter, modifying the energy spectrum produced by
a neutrino beam traversing the Earth. Here, we will discuss the reverse
problem, i.e. what could be learned about the Earth's interior from a single
neutrino baseline energy spectrum, especially about the Earth's mantle. We will
use a statistical analysis with a low-energy neutrino beam under very
optimistic assumptions. At the end, we will note that it is hard to find
petroleum with such a method, though it is not too far away from technical
feasibility.Comment: 6 pages, 4 figures, EPL LaTeX. Final version to be published in
Europhys. Let
Test of the Dimopouos-Hall-Raby Ansatz for Fermion Mass Matrices
By evolution of fermion mass matrices of the Fritzsch and the Georgi-Jarlskog
forms from the supersymmetric grand unified scale, DHR obtained predictions for
the quark masses and mixings. Using Monte Carlo methods we test these
predictions against the latest determinations of the mixings, the CP-violating
parameter epsilon_K and the B_d^0--Bbar_d^0 mixing parameter r_d. The
acceptable solutions closely specify the quark masses and mixings, but lie at
the edges of allowed regions at 90% confidence level.Comment: 11 pages, 1 figure (not included
Stau LSP and comparison with H^+(-) phenomenology
In supersymmetric models with explicit breaking of R-parity the lightest
supersymmetric particle (LSP) may be the lightest stau, \stau_1. Such a
scenario would provide a clear sign of R-parity violating SUSY, although its
phenomenology may resemble that of a charged Higgs boson, . We discuss
various ways of distinguishing a LSP \stau_1 from at future
colliders, and address the case of \stau_1 mimicking the signal for .
As an example we suggest that the recent L3 signal for and
could be more easily explained by a LSP
\stau_1.Comment: 22 pages, 2 figures, Revtex, short discussion and references adde
The see-saw mechanism: neutrino mixing, leptogenesis and lepton flavor violation
The see-saw mechanism to generate small neutrino masses is reviewed. After
summarizing our current knowledge about the low energy neutrino mass matrix we
consider reconstructing the see-saw mechanism. Low energy neutrino physics is
not sufficient to reconstruct see-saw, a feature which we refer to as ``see-saw
degeneracy''. Indirect tests of see-saw are leptogenesis and lepton flavor
violation in supersymmetric scenarios, which together with neutrino mass and
mixing define the framework of see-saw phenomenology. Several examples are
given, both phenomenological and GUT-related. Variants of the see-saw mechanism
like the type II or triplet see-saw are also discussed. In particular, we
compare many general aspects regarding the dependence of LFV on low energy
neutrino parameters in the extreme cases of a dominating conventional see-saw
term or a dominating triplet term. For instance, the absence of mu -> e gamma
or tau -> e gamma in the pure triplet case means that CP is conserved in
neutrino oscillations. Scanning models, we also find that among the decays mu
-> e gamma, tau -> e gamma and tau -> mu gamma the latter one has the largest
branching ratio in (i) SO(10) type I see-saw models and in (ii) scenarios in
which the triplet term dominates in the neutrino mass matrix.Comment: 26 pages, 7 figures. Expanded version of talk given at 10th Workshop
In High Energy Physics Phenomenology (WHEPP 10), January 2008, Chennai,
India. Typos corrected, comments and references adde
Unique Mass Texture for Quarks and Leptons
Texture specific quark mass matrices which are hermitian and hierarchical are
examined in detail . In the case of texture 6 zeros matrices, out of sixteen
possibilities examined by us, none is able to fit the low energy data (LED),
for example, , ,
, lies in the range (PDG). Similarly none of the 32 texture 5 zeros mass matrices considered
is able to reproduce LED. In particular, the latest data from LEP regarding
rules out all of them. In the texture 4
zeros case, we find that there is a unique texture structure for and
mass matrices which is able to fit the data.Comment: 12 pages, LaTeX,some changes in the references,minor changes in the
text,to appear in Phys Rev D(Rapid communications
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