Abstract
The experimental measurements on flavour physics, in tension with Standard Model predictions, exhibit large sources of lepton flavour universality violation. We perform an analysis of the effects of the global fits on the Wilson coefficients assuming the Standard Model Effective Field Theory with semileptonic dimension six operators at 1 TeV, and by including a set of different scenarios in which the New Physics contributions to the Wilson coefficients are present in one, two or three of the Wilson coefficients at a time. We compare the results of the global fit with respect to two cases: the Standard Model and the more general case in which new physics modifies three independent Wilson coefficients. The last mentioned scenario is the favoured one for explaining the tension between Standard Model predictions and B-physics anomalies, but a specific more restricted scenario can provide similar goodness with a smaller set of free parameters. A discussion of the implications of our analysis in leptoquark models is included.
Highlights
In the last few years, many interesting measurements on flavour physics have been performed at the LHC [1–15], BaBar [16] andBelle [17–21]
Several measurements of B meson decays performed in the recent years indicate a possible violation of lepton universality that may represent an indirect signal of New Physics
We provide an analysis of the effects of the global fits to the Wilson coefficients assuming a model-independent effective Hamiltonian approach and including a discussion of the consequences of our assumptions on the analysis in leptoquark models
Summary
In the last few years, many interesting measurements on flavour physics have been performed at the LHC [1–15], BaBar [16] and. Several experimental collaborations observed lepton flavour universality violating (LFUV) processes in B meson decays that would be a clear sign for physics beyond the Standard Model (SM). Some of these decays allow us to build optimised observables, as ratios of these decays, that are theoretically clean observables and whose measurements are in tension with SM predictions. The effective Hamiltonian approach allows us to perform a model-independent analysis of NP effects In this way, it is possible to obtain constraints on NP contributions to the Wilson coefficients of the Hamiltonian from the experimental results. Appendix A contains the list of observables that contribute to the global fit with their prediction in the most general scenario: the global fit to three independent Wilson coefficients receiving NP contributions
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