The role played by colorless gluon-clusters in the optical-geometrical approach to high-energy inelastic diffractive scattering is discussed. A simple analytical expression for the t-dependence of the integrated single diffractive cross section (t is the four-momentum transfer squared) is derived. Comparison with the existing data and predictions for future experiments are presented. ∗e-mail ad...

Deviations from the Standard Model (SM) expectations of the Lepton Universality (LU) breaking represent a powerful tool to probe New Physics (NP) effects. In the present document, we focus on R K = Γ(K e2)/Γ(K µ2), stressing the importance of R K measurements with an accuracy at the % level to probe lepton-flavor violating effects arising in Supersymmetric (SUSY) theories. Finally, we also revi...

In recent years a new potential symmetry of fundamental particle physics has been investigated — discrete quark-lepton symmetry. When this symmetry is implemented, however, it often leads to either of the unrealistic predictions m u = m e or m d = m e. This paper considers two possible ways models based on m d = m e can be made realistic.

1550-7998=20 The recent measurements of the solar neutrino mixing angle sol and the Cabibbo mixing angle C reveal a surprising relation, sol C ’ 4 , which has been interpreted as an evidence for quark-lepton unification. We show in realizations of quark-lepton unification that the PMNS mixing matrix can be decomposed into a CKM-like matrix and maximal mixing matrices. We explore a possibility t...

The recent experimental measurements of the solar neutrino mixing angle θsol and the Cabibbo mixing angle θC reveal a surprising relation, θsol + θC ≃ 4 . We review that while this empirical relation has been interpreted as a support of the idea of grand unification, it may be merely accidental in the sense that reproducing the relation at a low energy in the framework of grand unification may ...

Fermion compositeness and other new physics can be signalled by the presence of a strong four-fermion contact interaction. Here we present a study of leqq and !&?e’ contact interactions using the reactions: et!? --f e’+e’-, b&, CC at future e+elinear colliders with fi = 0.5 5 TeV and p+pcolliders with 4 = 0.5,4 TeV. We find that very large compositeness scales can be probed at these machines an...

A high-energy lepton-lepton collider will give us a unique possibility to study eγ and γγ interactions at high energies. The high-energy photons can be generated by Compton back-scattering of laser light on the high-energy lepton beams. With slightly reduced luminosities for eγ and γγ collisions compared to the lepton-lepton collider one, unique and complementary studies can be performed. A lin...

In the context of the future high energy – high luminosity electron and muon colliders, all the relevant four-lepton processes with the lepton family violation (LFV) are systematically classified. The most general LFV effective lagrangians are found, and the helicity differential cross sections for the LFV processes are calculated. The sixand eightlepton Standard Model (SM) backgrounds are disc...

We discuss the Higgs boson mass sum rules in the Minimal Super-symmetric Standard Model in order to estimate the upper limits on the masses of stop quarks as well as the lower bounds on the masses of the scalar Higgs boson state. The bounds on the scale of quark-lepton compositeness derived from the CDF Collaboration (Fermilab Teva-tron) data and applied to new extra gauge boson search is taken...

If quarks and leptons are made of constituents, then at the scale of constituent binding energies, there should appear new interactions among quarks and leptons. At energies much below the compositeness scale (Λ), these interactions are suppressed by inverse powers of Λ. The dominant effect should come from the lowest dimensional interactions with four fermions (contact terms), whose most gener...