Gino Isidori

On the breaking of lepton flavor universality in B decays

A bstractIn view of recent experimental indications of violations of Lepton Flavor Universality (LFU) in B decays, we analyze constraints and implications of LFU interactions, both using an effective theory approach, and an explicit dynamical model. We show that a simple dynamical model based on a SU(2)L triplet of massive vector bosons, coupled predominantly to third generation fermions (both quarks and leptons), can significantly improve the description of present data. In particular, the model decreases the tension between data and SM predictions concerning: i) the breaking of τ-μ universality in B→D(*)ℓν decays; ii) the breaking of μ-e universality in B → Kℓ+ℓ− decays. Indirectly, the model might also decrease the discrepancy between exclusive and inclusive determinations of |Vcb| and |Vub|. The minimal version of the model is in tension with ATLAS and CMS direct searches for the new massive vectors (decaying into τ+τ− pairs), but this tension can be decreased with additional non-standard degrees of freedom. Further pre-dictions of the model both at low- and high-energies, in view of future high-statistics data, are discussed.

Predictions for supersymmetric particle masses using indirect experimental and cosmological constraints

In view of the imminent start of the LHC experimental programme, we use the available indirect experimental and cosmological information to estimate the likely range of parameters of the constrained minimal supersymmetric extension of the Standard Model (CMSSM), using a Markov-chain Monte Carlo (MCMC) technique to sample the parameter space. The 95% confidence-level area in the (m0, m1/2) plane of the CMSSM lies largely within the region that could be explored with 1 fb−1 of integrated luminosity at 14 TeV, and much of the 68% confidence-level area lies within the region that could be explored with 50 pb−1 of integrated luminosity at 10 TeV. A same-sign dilepton signal could well be visible in most of the 68% confidence-level area with 1 fb−1 of integrated luminosity at 14 TeV. We discuss the sensitivities of the preferred ranges to variations in the most relevant indirect experimental and cosmological constraints and also to deviations from the universality of the supersymmetry-breaking contributions to the masses of the Higgs bosons.

Anomalies in B-decays and U(2) flavor symmetry

The collection of a few anomalies in semileptonic B-decays invites to speculate about the emergence of some strikingly new phenomena. Here we offer a possible interpretation of these anomalies in the context of a weakly broken

Supersymmetry and dark matter in light of LHC 2010 and XENON100 data

U(2)^5

Lepton Flavor Non-Universality in B decays from Dynamical Yukawas

U(2)5 flavor symmetry and leptoquark mediators.

Softened Gravity and the Extension of the Standard Model up to Infinite Energy

A bstractMotivated by additional experimental hints of Lepton Flavour Universality violation in B decays, both in charged- and in neutral-current processes, we analyse the ingredients necessary to provide a combined description of these phenomena. By means of an Effective Field Theory (EFT) approach, based on the hypothesis of New Physics coupled predominantly to the third generation of left-handed quarks and leptons, we show how this is possible. We demonstrate, in particular, how to solve the problems posed by electroweak precision tests and direct searches with a rather natural choice of model parameters, within the context of a U(2)q ×U(2)ℓ flavour symmetry. We further exemplify the general EFT findings by means of simplified models with explicit mediators in the TeV range: coloured scalar or vector leptoquarks and colour-less vectors. Among these, the case of an SU(2)L-singlet vector leptoquark emerges as a particularly simple and successful framework.

Pseudo-observables in Higgs decays

We make frequentist analyses of the CMSSM, NUHM1, VCMSSM and mSUGRA parameter spaces taking into account all the public results of searches for supersymmetry using data from the 2010 LHC run and the XENON100 direct search for dark matter scattering. The LHC data set includes ATLAS and CMS searches for

Stability of the electroweak ground state in the Standard Model and its extensions

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