421 research outputs found
Solutions of D_\alpha - 0 from Homogeneous Invariant Functions
We prove that the existence of a homogeneous invariant of degree n for a
representation of a semi-simple Lie group guarantees the existence of
non-trivial solutions of D_{\alpha} = 0: these correspond to the maximum value
of the square of the invariant divided by the norm of the representation to the
n^{th} power.Comment: 4 pages, late
SO(10)-Inspired See-Saw Mechanism
We determine the nu_{R} Majorana mass matrix from the experimental data on
neutrino oscillations in the framework of a see-saw SO(10) model, where we
impose the condition (M^R)_{33} = 0 to avoid too large fine-tunings in the
see-saw formula. We find a class of solutions with the two lowest neutrino
masses almost degenerate and the scale of the matrix elements of M^R in the
range 10^{11} -10^{12} GeV in agreement with Pati-Salam intermediate symmetry.
We find also solutions with smaller neutrino masses, for which the scale of M_R
depends on the solution to the "solar neutrino problem" and on the value of the
component of \nu_e along the highest mass eigenstate, U_{e3}.Comment: 16 pages, 3 tables, Late
Baryogenesis via leptogenesis in SO(10) models
We discuss the baryogenesis via leptogenesis mechanism within the
supersymmetric and nonsupersymmetric SO(10) models. We find that the
nonsupersymmetric model, endowed with an intermediate scale, is generally
favoured, unless some fine tuning occurs in the supersymmetric case.Comment: 9 pages, RevTex, with 1 figur
Neutrinoless double beta decay in SO(10) inspired seesaw models
By requiring the lower limit for the lightest right-handed neutrino mass,
obtained in the baryogenesis from leptogenesis scenario, and a Dirac neutrino
mass matrix similar to the up-quark mass matrix we predict small values for the
mass and for the matrix element responsible of the
neutrinoless double beta decay, around eV and
smaller than eV, respectively. The allowed range for the
mass of the heaviest right-handed neutrino is centered around the value of the
scale of B - L breaking in the SO(10) gauge theory with Pati-Salam intermediate
symmetry.Comment: 9 pages, RevTex4. Revised, title change
Charm nonleptonic decays and final state interactions
A global previous analysis of two-body nonleptonic decays of mesons has
been extended to the decays involving light scalar mesons. The allowance for
final state interaction also in nonresonant channels provides a fit of much
improved quality and with less symmetry breaking in the axial charges. We give
predictions for about 50 decay branching ratios yet to be measured. We also
discuss long distance contributions to the difference between
the and widths.Comment: 14 pages, no figures, plain TeX, uses harvmac.tex and tables.te
Neutrino masses and baryogenesis in SO(10) unified theories
We report on some phenomenological implications of a class of unified models
based on SO(10) gauge group, with intermediate symmetry group containing
SU(2)_R. Interesting predictions for neutrino masses are discussed, which are
relevant both for solar neutrino and dark matter problems, as well as a model
for the formation of the baryon asymmetry of the universe required by
primordial nucleosynthesis.Comment: Latex 16 pages, 1 ps figure. Appeared in Proceedings of seventh
International Workshop on Neutrino Telescopes, Venezia February 27 - March 1
1996, Editor M. Baldo Ceoli
A statistical approach for polarized parton distributions
A global next-to-leading order QCD analysis of unpolarized and polarized
deep-inelastic scattering data is performed with parton distributions
constructed in a statistical physical picture of the nucleon. The chiral
properties of QCD lead to strong relations between quarks and antiquarks
distributions and the importance of the Pauli exclusion principle is also
emphasized. We obtain a good description, in a broad range of and , of
all measured structure functions in terms of very few free parameters. We
stress the fact that at RHIC-BNL the ratio of the unpolarized cross sections
for the production of and in collisions, will directly probe
the behavior of the ratio for , a definite
and important test for the statistical model. Finally, we give specific
predictions for various helicity asymmetries for the production in
collisions at high energies, which will be measured with forthcoming
experiments at RHIC-BNL and are sensitive tests of the statistical model for
and .Comment: 49 pages, 27 eps figure
Nonleptonic Cabibbo Favoured -Decays and -Asymmetries for Charmed Final Hadron States in Isgur and Wise Theory
The Cabibbo allowed non-leptonic -decays in two hadrons are studied,
within the factorization hypothesis, in the framework of Isgur and Wise theory
for the matrix elements of the weak currents. The
symmetry relates to currents, which
have been measured in the semileptonic strange decays of charmed particles. By
assuming colour screening and allowing for invariant contributions from
the annihilation terms with charmed final states one is able to comply with the
present experimental knowledge.\\ The violating asymmetries in neutral
decays are given for charmed final states in terms of the angles. With
the central values found for the annihilation parameters there is a destructive
(constructive) interference between the direct and annihilation terms in the
Cabibbo allowed (doubly forbidden) amplitudes for the decays into
and so that they may be of the same order.
This would imply large asymmetries, for which however our present knowledge on
the amplitudes does not allow to predict even their sign.\\ We have better
confidence in our predictions for the charged final states than the neutral
ones and can draw the conclusion that the detection of the corresponding
asymmetries requires, at least, tagged neutral -particles.Comment: CERNTEX, 17 pages, DSF-92/23, INFN-NA-IV-92/2
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