Francisco J. Botella

Minimal Flavour Violation and Multi-Higgs Models

Abstract We propose an extension of the hypothesis of Minimal Flavour Violation (MFV) to general multi-Higgs models without the assumption of Natural Flavour Conservation (NFC) in the Higgs sector. We study in detail under what conditions the neutral Higgs couplings are only functions of V CKM and propose a MFV expansion for the neutral Higgs couplings to fermions.

New Physics and Evidence for a Complex CKM

We carefully analyse the present experimental evidence for a com- plex CKM matrix, even allowing for New Physics contributions to ǫK, a J/�KS , �MBd , �MBs , and theI = 1/2 piece of B → ρρ and B → ρπ. We emphasize the crucial role played by the angle γ in both providing irrefutable evidence for a complex CKM matrix and placing constraints on the size of NP contributions. It is shown that even if one allows for New Physics a real CKM matrix is excluded at a 99.92% C.L., and the probability for the phase γ to be in the interval (−170 ◦ ; −10 ◦ ) ∪ (10 ◦ ;170 ◦ ) is 99.7%.

Constraining models with vector-like fermions from FCNC in K and B physics

Abstract In this work we update the constraints on tree level FCNC couplings in the framework of a theory with n isosinglet vector-like down quarks. In this context, we emphasize the sensitivity of the B → J / ψK S CP asymmetry to the presence of new vector-like down quarks. This CP asymmetry, together with the rare decays B→X s,d l l and K→πν ν are the best options to further constrain the FCNC tree level couplings or even to point out, in the near future, the possible presence of vector-like quarks in the low energy spectrum, as suggested by GUT theories or models of large extra dimensions at the TeV scale.

Physical constraints on a class of two-Higgs doublet models with FCNC at tree level

A bstractWe analyse the constraints and some of the phenomenological implications of a class of two Higgs doublet models where there are flavour-changing neutral currents (FCNC) at tree level but the potentially dangerous FCNC couplings are suppressed by small entries of the CKM matrix V. This class of models have the remarkable feature that, as a result of a discrete symmetry of the Lagrangian, the FCNC couplings are entirely fixed in the quark sector by V and the ratio v2/v1 of the vevs of the neutral Higgs. The discrete symmetry is extended to the leptonic sector, so that there are FCNC in the leptonic sector with their flavour structure fixed by the leptonic mixing matrix. We analyse a large number of processes, including decays mediated by charged Higgs at tree level, processes involving FCNC at tree level, as well as loop induced processes. We show that in this class of models one has new physical scalars beyond the standard Higgs boson, with masses reachable at the next round of experiments.

The hunt for New Physics in the Flavour Sector with up vector-like quarks

A bstractWe analyse the possible presence of New Physics (NP) in the Flavour Sector and evaluate its potential for solving the tension between the experimental values of

How sensitive to FCNC can B0 CP asymmetries be

{A_{{J/\varPsi {K_S}}}}

Two-Higgs leptonic minimal flavour violation

and

ɛ′/ɛ and coherent decay of the K0−K¯0 system

\mathrm{Br}\left( {{B^{+}}\to {\tau^{+}}{\nu_{\tau }}} \right)

Tree-level flavor-changing neutral currents in the B system: >From CP asymmetries to rare decays

with respect to the Standard Model (SM) expectations. Updated model independent analyses, where NP contributions are allowed in

Invariant approach to flavour-dependent CP-violating phases in the MSSM

B_d^0-\bar{B}_d^0