I review the status of CP violation in the Standard Model from the combination of flavour constraints within the CKMfitter frequentist approach and I describe studies of New Physics restricted to the Delta F=2 sector to explain recent results on neut
ral-meson mixing. All results have been obtained using data available for the Winter 2012 conferences.
We reanalyse the topological susceptibility assuming the possibility of a significant paramagnetic suppression of the three-flavour quark condensate and a correlated enhancement of vacuum fluctuations of $sbar{s}$ pairs. Using the framework of resumm
ed ChPT, we point out that simulations performed near the physical point, with a significant mass hierarchy between u,d and s dynamical quarks, are not able to disentangle the contributions from the quark condensate and sea $sbar{s}$-pair fluctuations, and that simulations with three light quark masses of the same order are better suited for this purpose. We perform a combined fit of recent RBC/UKQCD data on pseudoscalar masses and decay constants as well as the topological susceptibility, and we reconsider the determination of lattice spacings in our framework, working out the consequences on the parameters of the chiral Lagrangian. We obtain Sigma(3;2 GeV)^1/3=243 pm 12 MeV for the three-flavour quark condensate in the chiral limit. We notice a significant suppression compared to the two-flavour quark condensate Sigma(2;2 GeV)/Sigma(3;2 GeV)=1.51pm 0.11 and we confirm previous findings of a competition between leading order and next-to-leading order contributions in three-flavour chiral series.
The vector form factor f_+(t) of the semileptonic decay D -> K l nu, measured recently with a high accuracy, can be used to determine the strong coupling constant g_{D_s^* D K}. The latter is related to the normalised coupling hat{g} releveant in hea
vy-meson chiral perturbation theory. This determination relies on the estimation of the residue of the form factor at the D_s^* pole and thus on an extrapolation of the form factor in the unphysical region (m_D-m_K)^2<t<(m_D+m_K)^2. We test this extrapolation for several parametrisations of the form factors by determining the value of hat{g}, whose value can be compared to other (experimental and theoretical) estimates. Several unsophisticated parametrisations, differing by the amount of physical information that they embed, are shown to pass this test. An apparently more elaborated parametrisation of form factors, the so-called z-expansion, is at variance with the other models, and we point out some significant shortcomings of this parametrisation for the problem under consideration.
