We discuss some experimental and theoretical results on single spin asymmetries (SSA) in high energy lepton-hadron and hadron-hadron reactions. In particular, recent results on meson SSA obtained by HERMES are considered in detail. We also discuss the SSA results obtained recently by COMPASS, as well as those from BRAHMS, PHENIX and STAR. Special attention is paid to a possible nonperturbative ...

Deviations from the Standard Model (SM) expectations of the Lepton Universality (LU) breaking represent a powerful tool to probe New Physics (NP) effects. Kaon physics is an obvious ground where to perform such tests, for instance in the well studied R K = B(K → eν)/B(K → μν). Supersymmetric (SUSY) extensions of the Standard Model can exhibit μ − e non-universal contributions. Their origin is t...

We examine resonant slepton production at the LHC with gravitinos in the final state. The slepton undergoes gauge decay into a neutralino and a lepton, the neutralino decays into a photon and a gravitino. By measuring the transverse masses of the γG̃ and the lγG̃ subsystems it is possible to accurately reconstruct both the slepton and the neutralino masses. In some regions of parameter space the ...

Nonstandard lepton-quark contact interactions may arise at low energies as a consequence of a common quark and lepton substructure or of heavy boson exchanges, when integrated out. There has recently been renewed interest @1# in contact interactions due to the fact that they are one of the potential explanations of the excess of events reported by H1 @2# and ZEUS @3#, the DESY ep collider at HE...

In the decay of Υ(4S), the decay time distribution of Υ(4S) → f + X, where f is a final state that both B and B 0 can decay to, is the sum of the decay time distributions of B → f and B → f . Using this general rule, we estimate the sensitivity of single lepton CP violation measurements with respect to that of traditional di-lepton measurements. We find that the sensitivity of the single lepton...

A new release of the Monte Carlo program HERWIG (version 6.4) is now available. The main new features are: spin correlations between the production and decay of heavy fermions, i.e. top quarks, τ leptons and SUSY particles; polarization effects in SUSY production processes in lepton-lepton collisions; an interface to TAUOLA for τ decays; MSSM Higgs processes in lepton-lepton collisions.

In supersymmetric extensions of the Standard Model, the Yukawa and/or mass terms of the heavy neutrinos can generate lepton flavour violating sleptonmass terms. These new supersymmetric sources of lepton flavour violation may both enhance the rates of charged lepton flavour violating processes, lα → lβγ, and generate distinct final states, like lβlα + jets +E/T , at future colliders. First, we ...

We propose a new scenario to simultaneously explain a large lepton asymmetry and a small baryon asymmetry. We consider a rolling scalar field and its derivative coupling to the lepton number current. The presence of an effective nonzero time derivative of the scalar field leads to CPT violation so that the lepton asymmetry can be generated even in thermal equilibrium as pointed out by Cohen and...