Ricardo González Felipe

Phenomenological and cosmological aspects of a minimal GUT scenario

Abstract Several phenomenological and cosmological aspects of a minimal extension of the Georgi–Glashow model, where the Higgs sector is composed by 5 H , 15 H , and 24 H , are studied. It is shown that the constraints coming from the unification of gauge interactions up to two-loop level predict light scalar leptoquarks. In this GUT scenario, the upper bound on the total proton decay lifetime is τ p ⩽ 1.4 × 10 36 years. The possibility to explain the matter–antimatter asymmetry in the universe through the decays of SU ( 2 ) L scalar triplets is also studied in the simplest extension of our GUT scenario, which consists on the addition of right-handed neutrinos. We find that a successful triplet seesaw leptogenesis implies an upper bound on the scalar leptoquark mass, M Φ b ≲ 10 6 − 7 GeV . We conclude that this GUT scenario can be tested at the next generation of proton decay experiments and future colliders through the production of scalar leptoquarks.

Models with three Higgs doublets in the triplet representations of A(4) or S-4

The work of R. G. F. and J. P. S. was partially supported by Portuguese national funds through FCT-Fundacao para a Ciencia e a Tecnologia, under the Projects No. PEst-OE/FIS/UI0777/2011 and No. CERN/FP/116328/2010, and by the EU RTN Project Marie Curie PITN-GA-2009-237920. The work of H. S. is funded by the European FEDER, Spanish MINECO, under the Grant No. FPA2011-23596.

Is right-handed neutrino degeneracy compatible with the solar and atmospheric neutrino data?

In light of the recent solar and atmospheric neutrino data, we investigate the possibility of having an exactly degenerate spectrum for heavy right-handed Majorana neutrinos at the grand unification scale. The analysis is performed in the context of the minimal supersymmetric standard model with unbroken R parity and extended with three heavy Majorana neutrino fields in order to implement the seesaw mechanism. In the absence of a Dirac-type leptonic mixing, the only source of lepton flavour violation is the right-handed neutrino sector. Inspired by GUT-motivated relations among the quark, charged-lepton and Dirac neutrino Yukawa coupling matrices, and after the inclusion of the radiative effects, we determine the effective neutrino mass matrix at the electroweak scale. Using then the latest global analyses of the solar and atmospheric data at 99% C.L., we conclude that, within this framework, the only solar solutions compatible with the experimental data are the LOW and LMA solutions, being the latter the most favoured one. At 90% C.L., only the LMA solution is allowed.

Neutrino observables from predictive flavour patterns

We look for predictive flavour patterns of the effective Majorana neutrino mass matrix that are compatible with current neutrino oscillation data. Our search is based on the assumption that the neutrino mass matrix contains equal elements and a minimal number of parameters, in the flavour basis where the charged lepton mass matrix is diagonal and real. Three unique patterns that can successfully explain neutrino observables at the

Natural gauge and gravitational coupling unification and the superpartner masses

3\upsigma

More about unphysical zeroes in quark mass matrices

3σ confidence level with just three physical parameters are presented. Neutrino textures described by four and five parameters are also studied. The predictions for the lightest neutrino mass, the effective mass parameter in neutrinoless double beta decays and for the CP-violating phases in the leptonic mixing are given.

Minimal anomaly-free chiral fermion sets and gauge coupling unification

A bstractWe study the cosmological evolution of asymmetries in the two-Higgs doublet extension of the Standard Model, prior to the electroweak phase transition. If Higgs flavour-exchanging interactions are sufficiently slow, then a relative asymmetry among the Higgs doublets corresponds to an effectively conserved quantum number. Since the magnitude of the Higgs couplings depends on the choice of basis in the Higgs doublet space, we attempt to formulate basis-independent out-of-equilibrium conditions. We show that an initial asymmetry between the Higgs scalars, which could be generated by CP violation in the Higgs sector, will be transformed into a baryon asymmetry by the sphalerons, without the need of B − L violation. This novel mechanism of baryogenesis through (split) Higgsogenesis is exemplified with simple scenarios based on the out-of-equilibrium decay of heavy singlet scalar fields into the Higgs doublets.

Unifying gauge couplings at the string scale

Abstract The possibility to achieve unification at the string scale in the context of the simplest supersymmetric grand unified theory is investigated. We find conservative upper bounds on the superpartner masses consistent with the unification of gauge and gravitational couplings, M G ˜ ≲ 5 TeV and M f ˜ ≲ 3 × 10 7 GeV , for the superparticles with spin one-half and zero, respectively. These bounds hint towards the possibility that this supersymmetric scenario could be tested at future colliders, and in particular, at the forthcoming LHC.