Opportunities From Precision Flavour Physics

The possible role of precision flavour physics, and particularly of B physics, in the next decade is briefly discussed. Few 2--3$\sigma$ deviations from the Standard Model found in present $B$ data are reviewed as potential forerunners of new physics signals to be looked for in next-generation experiments. The perspectives for theoretical calculations, in particular those based on lattice QCD, to match the expected progress in experimental precision are also discussed.Comment: 10 pages, 7 figures, proceedings of the 12th International Conference on B-Physics at Hadron Machines - BEAUTY 2009, September 07-12, 2009, Heidelberg, German

Theoretical uncertainty in sin 2beta: An update

The source of theoretical uncertainty in the extraction of sin 2beta from the measurement of the golden channel Bd -> J/psi K0 is briefly reviewed. An updated estimate of this uncertainty based on SU(3) flavour symmetry and the measurement of the decay Bd -> J/psi pi0 is also presented.Comment: 8 pages, 2 figures, 3 tables, Proceedings of CKM2010, the 6th International Workshop on the CKM Unitarity Triangle, University of Warwick, UK, 6-10 September 201

Theoretical status of epsilon'/epsilon

We review the theory of epsilon'/epsilon and present an updated phenomenological analysis using hadronic matrix elements from lattice QCD. The present status of the computation of epsilon'/epsilon, considering various approaches to the matrix-element evaluation, is critically discussed.Comment: 22 pages, 2 eps figures, based on the talks given by M.C. at "Les Rencontres de Physique de la Vallee d'Aoste", La Thuile (Italy), 27 February-4 March 2000 and by G.M. at the "XXXVth Rencontres de Moriond", Les Arcs 1800 (France), 11-18 March 200

The Global Electroweak and Higgs Fits in the LHC era

We update the global fit to electroweak precision observables, including the effect of the latest measurements at hadron colliders of the $W$ and top-quark masses and the effective leptonic weak mixing angle. We comment on the impact of these measurements in terms of constraints on new physics. We also update the bounds derived from the fit to the Higgs-boson signal strengths, including the observables measured at the LHC Run 2, and compare the improvements with respect to the 7 and 8 TeV results.Comment: 5+1 pages, 3 figures, 2 tables. Prepared for the Proceedings of the 5th LHCP Conference -Shanghai, May 2017- and the EPS-HEP 2017 Conference -Venice, July 2017. (LHCP version.

B→K∗ℓ+ℓ−B\to K^* \ell^+ \ell^- decays at large recoil in the Standard Model: a theoretical reappraisal

We critically reassess the theoretical uncertainties in the Standard Model calculation of the $B \to K^* \ell^+ \ell^-$ observables, focusing on the low $q^2$ region. We point out that even optimized observables are affected by sizable uncertainties, since hadronic contributions generated by current-current operators with charm are difficult to estimate, especially for $q^2 \sim 4 m_c^2\simeq 6.8$ GeV$^2$. We perform a detailed numerical analysis and present both predictions and results from the fit obtained using most recent data. We find that non-factorizable power corrections of the expected order of magnitude are sufficient to give a good description of current experimental data within the Standard Model. We discuss in detail the $q^2$ dependence of the corrections and their possible interpretation as shifts of the Standard Model Wilson coefficients.Comment: 33 pages, 7 figures, 11 tables. v2: fixed numerical error in S4 and typos; added discussion of the impact of future measurements; conclusions unchange

Direct CP Violation in B->phi K_s and New Physics

In the presence of large New Physics contributions to loop-induced b->s transitions, sizable direct CP violation in B-> phi K decays is expected on general grounds. We compute explicitly CP-violating effects using QCD factorization and find that, even in the restricted case in which New Physics has the same penguin structure as the Standard Model, the rate asymmetry can be of order one. We briefly discuss a more general scenario and comment on the inclusion of power-suppressed corrections to factorization.Comment: 3 page

On Flavourful Easter eggs for New Physics hunger and Lepton Flavour Universality violation

Within the standard approach of effective field theory of weak interactions for $\Delta B = 1$ transitions, we look for possibly unexpected subtle New Physics effects, here dubbed "flavourful Easter eggs". We perform a Bayesian global fit using the publicly available HEPfit package, taking into account state-of-the-art experimental information concerning these processes, including the suggestive measurements from LHCb of $R_{K}$ and $R_{K^{*}}$, the latter available only very recently. We parametrize New Physics contributions to $b \to s$ transitions in terms of shifts of Wilson coefficients of the electromagnetic dipole and semi-leptonic operators, assuming CP-conserving effects, but allowing in general for violation of lepton flavour universality. We show how optimistic/conservative hadronic estimates can impact quantitatively the size of New Physics extracted from the fit. With a conservative approach to hadronic uncertainties we find nonzero New Physics contributions to Wilson coefficients at the level of $\sim 3\sigma$, depending on the model chosen. Furthermore, given the interplay between hadronic contributions and New Physics effects in the leptonic vector current, a scenario with nonstandard leptonic axial currents is comparable to the more widely advocated one with New Physics in the leptonic vector current.Comment: 27 pages, 6 figures and 5 tables. v2: numerical results and plots replaced with higher statistics MC runs, references added. v3: final version to appear in EPJ

Electroweak precision observables and Higgs-boson signal strengths in the Standard Model and beyond: present and future

We present results from a state-of-the-art fit of electroweak precision observables and Higgs-boson signal-strength measurements performed using 7 and 8 TeV data from the Large Hadron Collider. Based on the HEPfit package, our study updates the traditional fit of electroweak precision observables and extends it to include Higgs-boson measurements. As a result we obtain constraints on new physics corrections to both electroweak observables and Higgs-boson couplings. We present the projected accuracy of the fit taking into account the expected sensitivities at future colliders.Comment: 34 pages, 30 figures, 23 table

Electroweak precision constraints at present and future colliders

We revisit the global fit to electroweak precision observables in the Standard Model and present model-independent bounds on several general new physics scenarios. We present a projection of the fit based on the expected experimental improvements at future $e^+ e^-$ colliders, and compare the constraining power of some of the different experiments that have been proposed. All results have been obtained with the HEPfit code.Comment: 6 + 1 pages, 4 figures, 6 tables. Minor corrections. Contribution to the Proceedings of the 38th International Conference on High Energy Physics, 3-10 August 2016, Chicago, U.S.