We propose a new mechanism to block the active-sterile neutrino oscillations in the Early Universe. We show that a typical consequence of theories where the lepton number is spontaneously broken is the existence of a coherent cosmologic Majoron field with strength proportional to the lepton and baryon numbers of the Universe. This field interacts with leptons and changes the potentials relevant...

Partonic interpretation of high-energy reactions is known to depend on a reference frame. Particularly, in the rest frame of the target Drell-Yan process looks like a freeing of the projectile ll̄ fluctuation, rather than qq̄ → ll̄ annihilation. The lightcone representation for Drell-Yan reaction is very similar to that in DIS and exposes a substantial contamination of soft interactions which turn...

The impact of possible sources of lepton-flavor mixing onK → πνν̄ decays is analysed. At the one-loop level lepton-flavor mixing originated from non-diagonal lepton mass matrices cannot generate a CP-conserving KL → πνν̄ amplitude. The rates of these modes are sensitive to leptonic flavor violation when there are at least two different leptonic mixing matrices. New interactions that violate both ...

We present and discuss constraints on supersymmetric type I seesaw models imposed by neutrino data, charged lepton flavor violation and thermal leptogenesis. 1 Supersymmetric seesaw mechanism and slepton mass matrix The observed neutrino oscillations imply the existence of neutrino masses and lepton flavor mixing, and give hints towards physics beyond the Standard Model. For example, the smalln...

The latest results on searches for Lepton Flavour and Number violation in K+→π∓μ±e+ K+→π−l+l+ with l=(μ,e) decays at the NA62 experiment CERN SPS are presented, improving previous limits.

In E6 models there are new particles whose baryon number is not uniquely assigned. We point out that the baryon and lepton number assignment to these particles can change the baryogenesis scenario significantly. We consider left-right symmetric extension of the standard model in which (B − L) quantum number is gauged. The identification of (B − L) with a generator of E6 is used to define the ba...

The phenomenological model that all quark and lepton mass matrices have the same zero texture, namely their (1,1), (1,3) and (3,1) components are zeros, is discussed in the context of SO(10) Grand Unified Theories (GUTs). The mass matrices of type I for quarks are consistent with the experimental data in the quark sector. For the lepton sector, consistent fitting to the data of neutrino oscilla...