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Jose W. F. Valle

Publications and source records attributed to Jose W. F. Valle.

47 records · Page 3Linked to original sources
arXiv1998

Charged Higgs Boson and Stau Phenomenology in the Simplest R-Parity Breaking Model

We consider the charged scalar boson phenomenology in the simplest effective low-energy R-parity breaking model characterized by a bilinear violation of R-parity in the superpotential. This induces a mixing between staus and the charged Higgs boson. We show that the charged Higgs boson mass can be lower than expected in the MSSM, even before including radiative corrections. We also study the charged scalar boson decay branching ratios and show that the R-parity violating decay rates can be comparable or even bigger than the R-parity conserving ones. Moreover, if the stau is the LSP it will have only decays into standard model fermions. These features could have important implications for charged supersymmetric scalar boson searches at future accelerators.

hep-ph↗
arXiv1998

Gauge and Yukawa Unification with Broken R-Parity

We study gauge and Yukawa coupling unification in the simplest extension of the Minimal Supersymmetric Standard Model (MSSM) which incorporates R-Parity violation through a bilinear superpotential term. Contrary to what happens in the MSSM, we show that bottom-tau unification at the scale M_GUT where the gauge couplings unify can be achieved for any value of tan(beta) by choosing appropriately the sneutrino vacuum expectation value. In addition, we show that bottom-tau-top unification occurs in a slightly wider tan(beta) range than in the MSSM.

hep-ph↗
arXiv1997

Physics Beyond the Desert

I review the observational status of neutrino physics, including the present hints for neutrino mass and the ways to reconcile the solar and atmospheric neutrino data with the existence of a hot dark matter component, and the possible hints from LSND. I also briefly discuss the electroweak symmetry breaking sector of the Standard Model (SM), focussing on supersymmetric models with broken R-parity and spontaneously broken lepton number. I discuss some of the signals expected at future accelerators such as LEP II and LHC. They serve to illustrate how neutrino mass effects may be testable not only at underground and nuclear physics installations but also at high energy collider experiments.

hep-ph↗
arXiv1997

Minimal Supergravity with R-Parity Breaking

We show that the minimal R-parity breaking model characterized by an effective bilinear violation of R-parity in the superpotential is consistent with minimal N=1 supergravity unification with radiative breaking of the electroweak symmetry and universal scalar and gaugino masses. This one-parameter extension of the MSSM-SUGRA model provides therefore the simplest reference model for the breaking of R-parity and constitutes a consistent truncation of the complete dynamical models with spontaneous R-parity breaking proposed previously. We comment on the lowest-lying CP-even Higgs boson mass and discuss its minimal N=1 supergravity limit, determine the ranges of $\tanβ$ and bottom quark Yukawa couplings allowed in the model, as well as the relation between the tau neutrino mass and the bilinear R-parity violating parameter.

hep-ph↗
arXiv1995

Neutrino-less Double Beta Decay and Physics Beyond the Standard Model

A brief sketch is given of the present observational status and future prospects of the physics of neutrino mass, including a survey of the various theoretical schemes of neutrino mass generation. Emphasis is given to those which are motivated by present experimental hints from solar and atmospheric neutrinos, as well as from cosmological data related to the dark matter question. The conceptual importance of neutrino-less double beta decay as a distinctive signature of the Majorana character of neutrinos is stressed. Barring accidental cancellations this process gives the strongest laboratory constraint on neutrino mass.

hep-ph↗
arXiv1994

Active Sterile Neutrino Conversions in a Supernova with Random Magnetic Fields

{Large enough random magnetic fields may affect in an important way neutrino conversion rates, even in the case where neutrinos have zero transition magnetic moments. We consider their effect in the case of active to sterile \neu conversions in a supernova and show that for KeV neutrino masses these limits may overcome those derived for the case of zero magnetic field.}

hep-ph↗
arXiv1994

Reconciling Cold Dark Matter with COBE/IRAS Plus Solar and Atmospheric Neutrino Data

We present a model where an unstable MeV Majorana tau \neu can naturally reconcile the cold dark matter model (CDM) with cosmological observations of large and small scale density fluctuations and, simultaneously, with data on solar and atmospheric neutrinos. The solar \neu deficit is explained through long wavelength, so-called {\sl just-so} oscillations involving conversions of \ne into both \nm and a sterile species \ns, while atmospheric \neu data are explained through \nm to \ne conversions. Future long baseline \neu oscillation experiments, as well as some reactor experiments will test this hypothesis. The model is based on the spontaneous violation of a global lepton number symmetry at the weak scale. This symmetry plays a key role in generating the cosmologically required decay of the \nt with lifetime $τ_{ν_τ} \sim 10^2 - 10^4$ seconds, as well as the masses and oscillations of the three light \neus \ne, \nm and \ns required in order to account for solar and atmospheric \neu data. It also leads to the invisibly decaying higgs signature that can be searched at LEP and future particle colliders.

hep-ph↗
arXiv1993

Beyond the Standard Model in Tau Decays

Invited talk at Second Workshop on JINR CTau Factory, Dubna, April 1993, updated version of earlier review given at Second Workshop on Tau Lepton Physics, Ohio, september 1992

hep-ph↗