Flavor Physics and Lattice QCD

Our ability to resolve new physics effects is, largely, limited by the precision with which we calculate. The calculation of observables in the Standard (or a new physics) Model requires knowledge of associated hadronic contributions. The precision of such calculations, and therefore our ability to leverage experiment, is typically limited by hadronic uncertainties. The only first-principles method for calculating the nonperturbative, hadronic contributions is lattice QCD. Modern lattice calculations have controlled errors, are systematically improvable, and in some cases, are pushing the sub-percent level of precision. I outline the role played by, highlight state of the art efforts in, and discuss possible future directions of lattice calculations in flavor physics.Comment: Invited review of lattice QCD in quark and lepton flavor physics. Presentation at the DPF 2013 Meeting of the American Physical Society Division of Particles and Fields, Santa Cruz, California, August 13-17, 201

Testing the Standard Model under the weight of heavy flavors

I review recently completed (since Lattice 2013) and ongoing lattice calculations in charm and bottom flavor physics. A comparison of the precision of lattice and experiment is made using both current experimental results and projected experimental precision in 2020. The combination of experiment and theory reveals several tensions between nature and the Standard Model. These tensions are reviewed in light of recent lattice results.Comment: 18 pages, 9 figures; Review at The 32nd International Symposium on Lattice Field Theory, 23-28 June, 2014, Columbia University New York, NY; PoS(LATTICE2014)002: Ver. 2 fixes several several typos, including labels in Fig. 3 and updates references, including the addition of recent results to Figs. 7 and

L’autocorrélation spatiale et les données de santé : une étude préliminaire

L'analyse de l'autocorrélation spatiale cherche à mesurer jusqu'à quel point la variation dans un ensemble de données réparties dans l'espace est due aux relations decontiguïté. Du point de vue mathématique, il existe deux façons d'aborder le problème : l'analyse de variance et le calcul d'un coefficient d'autocorrélation. Dans cette étude, une méthode du deuxième type est appliquée d'abord à un ensemble de carrelages d'essai possédant divers degrés d'autocorrélation spatiale et puis à la distribution spatiale de mortalité due aux maladies chroniques, à Montréal, en 1972. On conclut qu'elles révèlent une autocorrélation faible mais significative par rapport aux données de mortalité, et que d'autres facteurs suggérés dans la littérature récente de la géographie médicale pourraient bien avoir plus d'influence que la contiguïté spatiale elle-même.Spatial autocorrelation analysis attempts to measure the extent to which variation in spatially distributed data is due to the existence of contiguity relationships. From a mathematical point of view there are two general approaches to the problem : analysis of variance, and the calculation of a coefficient of spatial autocorrelation. In this study a method of the second type is applied, first to a series of test patterns with varying degrees of spatial autocorrelation, and then to the spatial distribution of chronic disease mortality in Montréal in 1972. The conclusion of the mortality data analysis were that a slight but significant autocorrelation effect was present and that other factors indicated in the recent medical geography literature could well be more influental than spatial contiguity itself

Bs→KℓνB_s \to K \ell \nu form factors from lattice QCD

We report the first lattice QCD calculation of the form factors for the standard model tree-level decay $B_s\to K \ell\nu$. In combination with future measurement, this calculation will provide an alternative exclusive semileptonic determination of $|V_{ub}|$. We compare our results with previous model calculations, make predictions for differential decay rates and branching fractions, and predict the ratio of differential branching fractions between $B_s\to K\tau\nu$ and $B_s\to K\mu\nu$. We also present standard model predictions for differential decay rate forward-backward asymmetries, polarization fractions, and calculate potentially useful ratios of $B_s\to K$ form factors with those of the fictitious $B_s\to\eta_s$ decay. Our lattice simulations utilize NRQCD $b$ and HISQ light quarks on a subset of the MILC Collaboration's $2+1$ asqtad gauge configurations, including two lattice spacings and a range of light quark masses.Comment: 24 pages, 21 figures; Ver. 2 matches published versio

B and Bs semileptonic decay form factors with NRQCD/HISQ quarks

We discuss our ongoing effort to calculate form factors for several B and Bs semileptonic decays. We have recently completed the first unquenched calculation of the form factors for the rare decay B -> K ll. Extrapolated over the full kinematic range of q^2 via model-independent z expansion, these form factor results allow us to calculate several Standard Model observables. We compare with experiment (Belle, BABAR, CDF, and LHCb) where possible and make predictions elsewhere. We discuss preliminary results for Bs -> K l nu which, when combined with anticipated experimental results, will provide an alternative exclusive determination of |Vub|. We are exploring the possibility of using ratios of form factors for this decay with those for the unphysical decay Bs -> eta_s as a means of significantly reducing form factor errors. We are also studying B -> pi l nu, form factors for which are combined with experiment in the standard exclusive determination of |Vub|. Our simulations use NRQCD heavy and HISQ light valence quarks on the MILC 2+1 dynamical asqtad configurations.Comment: 7 pages, 5 figures, presented at the 31st International Symposium on Lattice Field Theory (Lattice 2013), 29 July - 3 August 2013, Mainz, German