# “LFV and Neutrino Physics” by Paride Paradisi

Hi there in this damp day!!!

I am posting to summarizing the talk “Lepton Flavor Violation and Neutrino Physics” by Paride Paradisi.

Paride presented some insights on LFV, flavour symmetries, MFV, considering the current generation experiments.

SM predictions are quite precise and no evidence of large discrepancies with the experimental data have been determined. Furthermore, FCNC processes are very suppressed in SM. As a result, which kind of New Physics should we look for? and at what scale?

More precisely, more than one NP scales could be present (Gravity, Lepton Number Violation, Dark Matter…) and one can think to perform an effective analysis to discuss the operators which corresponds to FCNC processes:

Considering only the lepton sector, probably the most promising channels where to find NP are τ->μγ and μ->eγ(there has been this morning a nice talk by Alessandro Massimo Baldini on the results @ MEG) and the behaviour of the corresponding BRs is

Paride discussed the possibility that SUSY is the relevant NP originating such processes and a nice plot that summarizes the SUSY See-Saw I scenario is the following:

As one can see, the results depend on the value of the reactor angle and this stress the relevance of determine its value (see the talk by Thomas Schwetz today at 15:50).

I appreciate also the suggestion to study ratios of BR: indeed model builders quite often concentrate only on few relevant processes, but interesting relations and even specific features could be found when looking at rations of BR of different processes.

The talk ends discussing the possibility that flavour symmetries should in principle contribute to LFV transitions, if of course the scale of NP is sufficiently low. Indeed, generic flavour violation sources are forbidden up to scales of hundreds of TeV, unless a flavor symmetry is acting and in this case a scale of few TeV could be allowed.

Then an other question naturally arises: which is THE flavour symmetry that explains fermion masses and mixing? I invite you to follow the talks (and/or the summaries on this blog) by Steve King, today at 14:30, and by Guido Altarelli, at the very end of the conference. Let me also make a bit of publicity of the poster “A T’ flavour model for fermions and its phenomenology”:

(posted by Luca Merlo)