47 research outputs found
Anomaly Mediated Supersymmetry Breaking without R-Parity
We analyze the low energy features of a supersymmetric standard model where
the anomaly--induced contributions to the soft parameters are dominant in a
scenario with bilinear --parity violation. This class of models leads to
mixings between the standard model particles and supersymmetric ones which
change the low energy phenomenology and searches for supersymmetry. In
addition, --parity violation interactions give rise to small neutrino masses
which we show to be consistent with the present observations.Comment: 38 pages, 15 figures. For higher resolution figures go to
http://www.fma.if.usp.br/~magro/figures
On the possibility of a very light A^0 at low \tan\beta
The searches at LEP II for the processes e^+e^-\to h^0Z and e^+e^-\to h^0A^0
in the Minimal Supersymmetric Standard Model (MSSM) fail to exclude regions of
the m_h,m_A plane where \tan\beta <1, thus allowing a very light A^0 (m_A< 20
GeV). Such a parameter choice would predict a light H^\pm with m_{H^\pm}< m_W.
Although the potentially large branching ratio for H^\pm \to A^0 W^* would
ensure that H^\pm also escaped detection in direct searches at LEP II and the
Tevatron Run I, we show that this elusive parameter space is overwhelmingly
disfavoured by electroweak precision measurements.Comment: 11 pages, 2 figures, Revtex, references added, minor additions to
tex
Solar Neutrino Masses and Mixing from Bilinear R-Parity Broken Supersymmetry: Analytical versus Numerical Results
We give an analytical calculation of solar neutrino masses and mixing at
one-loop order within bilinear R-parity breaking supersymmetry, and compare our
results to the exact numerical calculation. Our method is based on a systematic
perturbative expansion of R-parity violating vertices to leading order. We find
in general quite good agreement between approximate and full numerical
calculation, but the approximate expressions are much simpler to implement. Our
formalism works especially well for the case of the large mixing angle MSW
solution (LMA-MSW), now strongly favoured by the recent KamLAND reactor
neutrino data.Comment: 34 pages, 14 ps figs, some clarifying comments adde
Supersymmetry Unification Predictions for M_top V_cb and tan(beta)
We study the predictions for M_top, tan(beta) and V_cb in a popular texture
ansatze for the fermion mass matrices. We do this both for the Minimal
Supersymmetric Standard Model (MSSM) and for the simplest model (MSSM-BRpV)
where a bilinear R-Parity violating term is added to the superpotential. We
find that taking the experimental values for M_top and V_cb at 99 % C.L. and
the GUT relations h_b=h_tau and (V_cb)^2=h_c/h_t within 5 %, the large
tan(beta) solution, characteristic in the MSSM with bottom--tau unification,
becomes disallowed. In contrast the corresponding allowed region for the
MSSM-BRpV is slightly larger. We also find that important modifications occur
if we relax the texture conditions at the GUT scale. For example, if the GUT
relations are imposed at 40 %, the large tan(beta) branch in the MSSM becomes
fully allowed. In addition, in MSSM-BRpV the whole tan(beta)-M_top plane become
allowed, finding unification at any value of tan(beta).Comment: 15 pages, including 6 figures. Late
Tinnitus prevalence in Europe: a multi-country cross-sectional population study
BackgroundTinnitus prevalence studies report large variability across countries that might be due to inconsistent research methods. Our study aimed to report a single Pan-European estimate for tinnitus prevalence and investigate the effect of individual and country-level characteristics on prevalence. We explored the relationships of healthcare resource use and hearing difficulty with tinnitus symptoms.MethodsBetween 2017-2018, a cross-sectional European Tinnitus Survey (ETS) was conducted in 12 European Union nations (Bulgaria, England, France, Germany, Greece, Ireland, Italy, Latvia, Poland, Portugal, Romania, and Spain), using a standardised set of tinnitus-related questions and response options in country-specific languages. We recruited 11,427 adults aged ≥18 years.FindingsPrevalence of any tinnitus was 14·7% (14·0% in men and 15·2% in women), ranging from 8·7% in Ireland to 28·3% in Bulgaria. Severe tinnitus was found in 1·2% participants (1·0% in men and 1·4% in women), ranging from 0·6% in Ireland to 4·2% in Romania. Tinnitus prevalence significantly increased with increasing age and worsening of hearing status. Healthcare resource use for tinnitus increased with increasing tinnitus symptom severity.InterpretationThis is the first multinational report of Pan-European tinnitus prevalence using standardised questions. The overall prevalence estimates refine previous findings, although widespread inter-country heterogeneity was noted. The results indicate that more than 1 in 7 adults in the EU have tinnitus. Extrapolating to the overall population, approximately 65 million adults in EU28 have tinnitus, 26 million have bothersome tinnitus and 4 million have severe tinnitus.FundingNational Institute for Health Research, European Union's Horizon 2020, Medical Research Council, and GENDER-Net Co-Plus Fund
Reconstructing Neutrino Properties from Collider Experiments in a Higgs Triplet Neutrino Mass Model
We extend the minimal supersymmetric standard model with bilinear R-parity
violation to include a pair of Higgs triplet superfields. The neutral
components of the Higgs triplets develop small vacuum expectation values (VEVs)
quadratic in the bilinear R-parity breaking parameters. In this scheme the
atmospheric neutrino mass scale arises from bilinear R-parity breaking while
for reasonable values of parameters the solar neutrino mass scale is generated
from the small Higgs triplet VEVs. We calculate neutrino masses and mixing
angles in this model and show how the model can be tested at future colliders.
The branching ratios of the doubly charged triplet decays are related to the
solar neutrino angle via a simple formula.Comment: 19 pages, 4 figures; one formula corrected, two author's names
corrected; some explanatory comments adde
Unification of gauge couplings and the tau neutrino mass in Supergravity without R-parity
Minimal R-parity violating supergravity predicts a value for
smaller than in the case with conserved R-parity, and therefore closer to the
experimental world average. We show that the R-parity violating effect on the
prediction comes from the larger two-loop b-quark Yukawa contribution
to the renormalization group evolution of the gauge couplings which
characterizes R-parity violating supergravity. The effect is correlated to the
tau neutrino mass and is sensitive to the initial conditions on the soft
supersymmetry breaking parameters at the unification scale. We show how a few
percent effect on may naturally occur even with tau neutrino
masses as small as indicated by the simplest neutrino oscillation
interpretation of the atmospheric neutrino data from Super-Kamiokande.Comment: Latex, 21 pages including 2 figure
Neutrino properties and the decay of the lightest supersymmetric particle
Supersymmetry with broken R-parity can explain the neutrino mass squared
differences and mixing angles observed in neutrino oscillation experiments. In
the minimal model, where R-parity is broken only by bilinear terms, certain
decay properties of the lightest supersymmetric particle (LSP) are correlated
with neutrino mixing angles. Here we consider charginos, squarks, gluinos and
sneutrinos being the LSP and calculate their decay properties in bilinear
R-parity breaking supersymmetry. Together with the decays of charged scalars
and neutralinos calculated previously this completes the proof that bilinear
R-parity breaking as the source of neutrino masses will be testable at future
colliders. Moreover, we argue that in case of GMSB, the decays of the NLSP can
be used to test the model.Comment: 15 pages, 8 figure
R--Parity Violating Signals for Chargino Production at LEP II
We study chargino pair production at LEP II in supersymmetric models with
spontaneously broken R-parity. We perform signal and background analyses,
showing that a large region of the parameter space of these models can be
probed through chargino searches at LEP II. In particular, we determine the
attainable limits on the chargino mass as a function of the magnitude of the
effective bilinear R-parity violation parameter , demonstrating that
LEP II is able to unravel the existence of charginos with masses almost up to
its kinematical limit even in the case of R-parity violation. This requires the
study of several final state topologies since the usual MSSM chargino signature
is recovered as . Moreover, for sufficiently large
values, for which the chargino decay mode dominates,
we find through a dedicated Monte Carlo analysis that the mass
bounds are again very close to the kinematic limit. Our results establish the
robustness of the chargino mass limit, in the sense that it is basically
model-independent. They also show that LEP II can establish the existence of
spontaneous R-parity violation in a large region of parameter space should
charginos be produced.Comment: improved analyses; 31 pages and 9 figures (included
Charged lepton Flavor Violation in Supersymmetry with Bilinear R-Parity Violation
The simplest unified extension of the Minimal Supersymmetric Standard Model
with bi-linear R-parity violation naturally predicts a hierarchical neutrino
mass spectrum, suitable to explain atmospheric and solar neutrino fluxes. We
study whether the individual violation of the lepton numbers L_{e,mu,tau} in
the charged sector can lead to measurable rates for BR(mu->e gamma)and
$BR(tau-> mu gamma). We find that some of the R-parity violating terms that are
compatible with the observed atmospheric neutrino oscillations could lead to
rates for mu->e gamma measurable in projected experiments. However, the Delta
m^2_{12} obtained for those parameters is too high to be compatible with the
solar neutrino data, excluding therefore the possibility of having measurable
rates for mu->e gamma in the model.Comment: 29 pages, 8 figures. Constraint from solar neutrino data included,
conclusions changed respect v