arXiv subjects

Francesca M. Borzumati

Publications and source records attributed to Francesca M. Borzumati.

3 recordsLinked to original sources

arXiv1997

On the Minimal Messenger Model

We study the Minimal Messenger Model, a minimal version of Gauge Mediated Supersymmetry Breaking models. Boundary conditions equal to zero for trilinear and bilinear soft parameters at the messenger scale make this model free from the supersymmetric CP problem and extremely predictive. These boundary conditions and the vicinity of the messenger scale to the electroweak one, require a careful implementation of the mechanism of radiative breaking of $SU(2)\times U(1)$. We assess the importance of considering the complete one-loop effective potential and of including a set of logarithmic two-loop corrections to the B parameter for the correct determination of the electroweak minimum. We analyze the resulting low-energy spectrum and give predictions of interest for future experimental searches.

hep-ph↗

arXiv1996

Neutrino Masses and Mixing in Supersymmetric Models without $R$ Parity

We study neutrino masses and mixing in Supersymmetric Models without $R$ parity and with generic soft Supersymmetry breaking terms. Neutrinos acquire mass from various sources: tree level neutrino--neutralino mixing, loop effects and non--renormalizable operators. Abelian horizontal symmetries (invoked to explain the smallness and hierarchy in quark parameters) replace $R$ parity in suppressing neutrino masses. We find lower bounds on the mixing angles: $\sinθ_{ij} \gsim m(\ell_i^-)/m(\ell_j^-)$ ($i<j$) and unusual order of magnitude predictions for neutrino mass ratios: $m(ν_e)/m(ν_μ)\sim\sin^2θ_{12}$; $m(ν_i)/m(ν_τ)\sim 10^{-7} \sin^2θ_{i3}$ ($i=1,2$). Bounds from laboratory experiments exclude $m_{ν_τ} \gsim 3\ MeV$ and the cosmological constraint that excludes $m_{ν_τ} \gsim 100\ eV$ is not evaded. Neither the solar nor the atmospheric neutrino problems are likely to be solved by $ν_μ-ν_e$ oscillations. These conclusions can be evaded if holomorphy plays an important role in the lepton Yukawa couplings.

hep-ph↗

arXiv1994

Implications for Supersymmetric Dark Matter Detection from Radiative $b$ Decays

We point out that combinations of parameters that predict large counting rates in experiments searching for supersymmetric dark matter often tend to predict a very large branching ratio for the inclusive decay \bsg. The recent measurement of this branching ratio, therefore, indicates that searches for supersymmetric dark matter might be even more difficult than previously anticipated.

hep-ph↗