Welcome to Ofelia Pisanti's home page

Big Bang Nucleosynthesis and Cosmic Microwave Background Radiation. The large amount of new and precise data on the structure of the universe, which are continually supplied by new generation experiments, provides a severe arena where to test new models for fundamental interactions. In this respect, the theoretical predictions on Big Bang Nucleosynthesis (BBN), which are considered one of the great successes of the hot Big Bang theory, have been refined in order to reach the same level of precision of the new experimental data, by including, in the proton to neutron conversion rates, radiative corrections, finite nucleon mass and plasma effects. All these contributions have been included in a numerical BBN code which calculates the relevant cosmological observables. With the help of this numerical tool, it is possible to perform a more careful comparison of crucial cosmological parameters, such as the baryon fraction and the "effective" number of neutrinos, with the corresponding values for these parameters obtained by the study of the Cosmic Microwave Background Anisotropy data. The combined analysis seems to show a spectacular inner consistency of the standard cosmological scenario, and this allows also to fix stringent bounds on the neutrino asymmetry parameters not easily obtainable in a different way;

Neutrino physics in the Pierre Auger Observatory experiment on cosmic rays. The identification of neutrino induced showers in the Auger experiment is of great interest, for the possible implications on neutrino production mechanisms and interactions in the universe. This motivates the upgrade of the MonteCarlo CORSIKA, used for simulating cosmic ray showers by the Auger collaboration, since at the moment it does not recognize neutrinos as initial particles. I am currently working on a modified version of CORSIKA for inclined showers started by neutrinos, which uses an intermediate call to the MonteCarlo HERWIG for simulating the first neutrino interaction;

Deep Inelastic Phenomenology. Two different scenarios can be considered for the violation of the Ellis and Jaffe sum rule, one referring to the contribution of the gluon polarization and the other one to the role of Pauli principle, which favours the dominance in the proton of the quark u with respect to the others. The data on polarized deep inelastic scattering have been analyzed for comparing these two interpretations. For the numerical evolution of the structure functions a Fortran code was built, which uses the method of Jacobi polynomials. This was the argument of my Ph. D. thesis;

SO(10) GUT Theories. I studied the Higgs potential for the breaking of the SO(10) gauge group to the intermediate group SU(3)xSU(2)xSU(2)xU(1). This model can accommodate a sufficiently large lifetime for proton decay and values for the neutrino masses interesting for the closure of the universe and the MSW mechanism. This was the argument of my Laurea thesis. Moreover, the possibility of generating the observed baryon asymmetry of the universe in a particular SO(10) gauge model has been studied, testing it against the limits coming from experimental data: proton lifetime and neutrino oscillations. Further, the symmetry-breaking patterns of some models of Grand Unified Theories have been analyzed from the point of view of a criterion of renormalization-group naturalness;

Particle phenomenology. I worked time by time on different arguments in Particle Phenomenology:
CP Violation: a particular asymmetry in the charged pion energy in the decay into three pions of the neutral kaons can improve our knowledge of the CP violation parameter, epsilon.
Fermion mass matrices: in a particular basis the relation between the parameters in the Cabibbo-Kobaiashi-Maskawa matrix and the fermion mass matrices does not contain arbitrary parameters and the entries in the mass matrices can be univocally determined.