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D. F. Carvalho

Publications and source records attributed to D. F. Carvalho.

5 recordsLinked to original sources
arXiv2002

Tau Flavour Violation in Sparticle Decays at the LHC

We consider sparticle decays that violate tau lepton number, motivated by neutrino oscillation data. We work in the context of the constrained minimal supersymmetric extension of the Standard Model (CMSSM), in which the different sleptons have identical masses at the GUT scale, and neutrino Dirac Yukawa couplings mix them. We find that the branching ratio for decay of the heavier neutralino chi_2 to chi + tau mu is enhanced when the LSP mass m_chi = m_stau_1, including the region of CMSSM parameter space where coannihilation keeps the relic chi density within the range preferred by cosmology. Thus chi_2 to chi + tau mu decay may provide a physics opportunity for observing the violation of tau lepton number at the LHC that is complementary to tau to mu + gamma decay. Likewise, chi_2 to chi + e mu decay is also enhanced in the coannihilation region, providing a complement to mu to e + gamma decay.

hep-ph↗
arXiv2002

Lepton-Flavour Violation in SUSY with and without R-parity

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 consider three different scenarios, the fist one corresponds to the Minimal Supersymmetric Standard Model with non-universal soft terms. In the other two cases the violation of flavor in the leptonic charged sector is associated to the neutrino problem in models with a see-saw mechanism and with R-parity violation respectively.

hep-ph↗
arXiv2002

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.

hep-ph↗
arXiv2001

Charged-Lepton-Flavour Violation in the CMSSM in View of the Muon Anomalous Magnetic Moment

We use the BNL E821 measurement of g - 2, the anomalous magnetic moment of the muon, to normalize, within a supersymmetric GUT framework, constrained MSSM (CMSSM) predictions for processes that violate charged-lepton flavour conservation, including mu to e gamma, mu to e conversion and K^0_L to mu e. We illustrate our analysis with two examples of lepton mass matrix textures motivated by data on neutrino oscillations. We find that mu to e gamma may well occur at a rate within one or two (two or three) orders of magnitude of the present experimental upper limit if g - 2 is within the one- (two-)standard deviation range indicated by E821. We also find that mu to e conversion is likely to occur at rate measurable by MECO, and there is a chance that K^0_L to mu e may be observable in an experiment using an intense proton source.

hep-ph↗