We discuss the possibility of introducing an SU(2) global flavour symmetry in the context of flat extra dimensions. In particular we concentrate on the 5-dimensional case and we study how to obtain the flavour structure of the Standard Model quark sector compactifying the fifth dimension on the orbifold S1/Z2 à la Scherk-Schwarz (SS). We show that in this case it is possible to justify the five...

We consider models of inflation in supergravity with a shift symmetry. We focus on models with one moduli and one inflaton field. The presence of this symmetry guarantees the existence of a flat direction for the inflaton field. Mildly breaking the shift symmetry using a superpotential which depends not only on the moduli but also on the inflaton field allows one to lift the inflaton flat direc...

We study the processes WLWL → tt̄ and WLZL → tb̄ (t̄b) at future lepton colliders as probes of the couplings of the top quark to resonances at the TeV scale. We consider the cases in which the dominant low energy feature of a strongly interacting electroweak symmetry breaking sector is either a scalar or a vector resonance with mass near 1 TeV. We find that future lepton colliders with high energy...

We explore a nonlinear realization of the (2+1)-dimensional Lorentz symmetry with a constant vacuum expectation value of the second rank anti-symmetric tensor field. By means of the nonlinear realization, we obtain the low-energy effective action of the Nambu-Goldstone bosons for the spontaneous Lorentz symmetry breaking. [email protected]

We discuss the possibility of introducing an SU(2) global flavour symmetry in the context of flat extra dimensions. In particular we concentrate on the 5-dimensional case and we study how to obtain the flavour structure of the Standard Model quark sector compactifying the fifth dimension on the orbifold S1/Z2 à la Scherk-Schwarz (SS). We show that in this case it is possible to justify the five...

The status of the theoretical effort to calculate charge-symmetry-breaking pion production reactions will be presented. The main emphasis will be on the dd → απ0 reaction, especially in relation to the recent IUCF experiment. Suggestions for future theoretical and experimental work will be made.