Francesco Caravaglios

Indication for light sneutrinos and gauginos from precision electroweak data

The present standard model fit of precision data has a low confidence level, and is characterized by a few inconsistencies. We look for supersymmetric effects that could improve the agreement among the electroweak precision measurements and with the direct lower bound on the Higgs mass. We find that this is the case particularly if the 3.6 σ discrepancy between sin 2θeff from leptonic and hadronic asymmetries is finally settled more on the side of the leptonic ones. After the inclusion of all experimental constraints, our analysis selects light sneutrinos, with masses in the range 55-80 GeV, and charged sleptons with masses just above their experimental limit, possibly with additional effects from light gauginos. The phenomenological implications of this scenario are discussed.

ELECTROWEAK PRECISION TESTS: A CONCISE REVIEW 1

1. Introduction 2. Status of the Data 3. Precision Electroweak Data and the Standard Model 4. A More General Analysis of Electroweak Data 4.1 Basic Definitions and Results 4.2 Experimental Determination of the Epsilon Variables 4.3 Comparing the Data with the Minimal Supersymmetric Standard Model 5. Theoretical Limits on the Higgs Mass 6. Conclusion

Gauge boson families in grand unified theories of fermion masses: E_6^4 x S_4

In third quantization the origin of fermion families is easy to understand: the electron field, the muon field and the tau field are identical fields in precisely the same sense as three electrons are identical and indistinguishable particles of a theory of second quantization. In both cases, the permutation of these fields or particles leaves the Lagrangian invariant. One can also extend the concept of family to gauge bosons. This can be obtained through the semidirect product of the gauge group with the group of permutations of n objects. In this paper we have studied the group . We explain why we have chosen E6 as fundamental gauge group factor and why we start with a model with four gauge boson/fermion families to accommodate and to fit the Standard Model with only three fermion families. We suggest a possible symmetry breaking pattern of that could explain quark, lepton and neutrino masses and mixings.

Fermion mass in E 6 GUT with discrete family permutation symmetry S 3

A discrete symmetry S 3 easily explains all neutrino data. However it is not obvious the embedding of S 3 in GUT where all fermions live in the same representation. We show that embedding S 3 in E 6 it is possible to make distinction between neutrinos and the rest of matter fermions1.