Ana M. Teixeira

Impact of θ13 on lepton flavour violating processes within SUSY seesaw

We study the impact of neutrino masses and mixings on LFV processes within the context of the supersymmetric seesaw scenario, where the CMSSM is extended by three right-handed (s)neutrinos. A hierarchical spectrum is considered for both heavy and light neutrinos. We systematically analyse the interesting relation between the leptonic mixing angle �13 and LFV muon and tau decays, namely lj → li and lj → 3li, and discuss the interplay with the other relevant parameters. We require compatibility with low energy neutrino data, bounds on both LFV decays and charged lepton electric dipole moments, and impose a successful baryogenesis via thermal leptogenesis. Particular emphasis is given to the implications that a future �13 measurement can have on our knowledge of the heavy neutrino sector.

Theoretical predictions for the direct detection of neutralino dark matter in the NMSSM

We analyse the direct detection of neutralino dark matter in the framework of the Next-to-Minimal Supersymmetric Standard Model. After performing a detailed analysis of the parameter space, taking into account all the available constraints from LEPII, we compute the neutralino-nucleon cross section, and compare the results with the sensitivity of detectors. We find that sizable values for the detection cross section, within the reach of dark matter detectors, are attainable in this framework. For example, neutralino-proton cross sections compatible with the sensitivity of present experiments can be obtained due to the exchange of very light Higgses with

Spontaneous CP violation in non-minimal supersymmetric models

m_{h_1^0}\lsim 70

Testing the Majorana nature of neutralinos in supersymmetric theories

GeV. Such Higgses have a significant singlet composition, thus escaping detection and being in agreement with accelerator data. The lightest neutralino in these cases exhibits a large singlino-Higgsino composition, and a mass in the range

Flavor changing neutral currents in supersymmetric multi-Higgs doublet models

50\lsim m_{\tilde\chi_1^0}\lsim 100

Phenomenological viability of orbifold models with three Higgs families

GeV.

LFV in tau and muon decays within SUSY seesaw

We study the possibilities of spontaneous CP violation in the Next-to-Minimal Supersymmetric Standard Model with an extra singlet tadpole term in the scalar potential. We calculate the Higgs boson masses and couplings with radiative corrections including dominant two loop terms. We show that it is possible to satisfy the LEP constraints on the Higgs boson spectrum with non-trivial spontaneous CP violating phases. We also show that these phases could account for the observed value of ?K.

Lepton Flavour Violation in charged leptons within SUSY-seesaw

Abstract We discuss selectron pair production in e − e − scattering. These processes can only occur via t -channel neutralino exchange, provided that the neutralinos are Majorana fermions. We concentrate on the processes e − e − → e L e L , e R e R →e − χ 1 0 e − χ 2 0 →e − χ 1 0 e − χ 1 0 f f , in which a complete determination of the final state momenta is possible without using the selectron masses as input. The experimental reconstruction of the selectron masses in this decay channel provides clear evidence of the Majorana character of the neutralinos, which is confirmed by the analysis of the electron energy spectrum.

Synergy and complementarity between neutrino physics and low energy intensity frontiers

We conduct a general discussion of supersymmetric models with three families in the Higgs sector. We analyse the scalar potential, and investigate the minima conditions, deriving the mass matrices for the scalar, pseudoscalar and charged states. Depending on the Yukawa couplings and the Higgs spectrum, the model might allow the occurrence of potentially dangerous flavour changing neutral currents at the tree-level. We compute model-independent contributions for several observables, and as an example we apply this general analysis to a specific model of quark-Higgs interactions, discussing how compatibility with current experimental data constrains the Higgs sector.

Theoretical aspects of charged Lepton Flavour Violation

We discuss the phenomenological viability of string multi-Higgs doublet models, namely a scenario of heterotic Z3 orbifolds with two Wilson lines, which naturally predicts three supersymmetric families of matter and Higgs fields. We study the orbifold parameter space, and discuss the compatibility of the predicted Yukawa couplings with current experimental data. We address the implications of tree-level flavour changing neutral processes in constraining the Higgs sector of the model, finding that viable scenarios can be obtained for a reasonably light Higgs spectrum. We also take into account the tree-level contributions to indirect CP violation, showing that the experimental value of ?K can be accommodated in the present framework.