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

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

Form factors for B and B_s semileptonic decays with NRQCD/HISQ quarks

We discuss preliminaries of a calculation of the form factors for the semileptonic decays B -> pi lv, B_s -> K lv, and B -> K ll. We simulate with NRQCD heavy and HISQ light valence quarks on the MILC 2+1 dynamical asqtad configurations. The form factors are calculated over a range of momentum transfer to allow determination of their shape and the extraction of |V_ub|. Additionally, we are calculating ratios of these form factors to those for the unphysical decay B_s -> eta_s. We are studying the possibility of combining these precisely determined ratios with future calculations of B_s ->eta_s using HISQ b-quarks to generate form factors with significantly reduced errors.Comment: 7 pages, 5 figures. Proceedings of the 30th International Symposium on Lattice Field Theory - Lattice 2012; June 24-29, 2012; Cairns, Australi

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

The method of computer-aided bionic surface modeling in objects design

The research data on the shaping principles in the self-developing natural systems are taken as a basis for creation of a computer-aided system of a specific surface type modeling being the natural system with a common classical, measured structure. The aim is to automate the process of obtaining surfaces and use them to create visual comfortable environments and aesthetic design objects. There have been identified the organization principles of self-developing natural structures on the basis of the mathematical functions. The options of integration between the mathematical representation of the system and its design realization by solid modeling are recommended and based thereon the versions of the design objects are designed. There set up the principles of the visual evaluation of the produced objects

Neutral B mixing from 2+1 flavor lattice QCD

We present an update of the Fermilab-MILC Collaboration's calculation of hadronic matrix elements for B^0-\bar{B^0} mixing. This work is a more extended analysis than our recent publication of the SU(3)-breaking ratio xi [arXiv:1205.7013]. We use the asqtad staggered action for light valence quarks in combination with the Fermilab interpretation of the Sheikoleslami-Wohlert action for heavy quarks. The calculations use MILC's 2+1 flavor asqtad ensembles. Ensembles include four lattice spacings from approximately 0.125 fm to 0.045 fm and up/down to strange quark mass ratios as low as 0.05. Our calculation covers the complete set of five operators needed to describe B mixing in the Standard Model and beyond. In addition to an update including a fuller set of analyzed data, we comment on the form of the staggered ChPT extrapolation function.Comment: 7 pages, 2 figures; Proceedings of the 30th International Symposium on Lattice Field Theory, June 24-29, 2012, Cairns, Australi

Open orbifold Gromov-Witten invariants of [C^3/Z_n]: localization and mirror symmetry

We develop a mathematical framework for the computation of open orbifold Gromov-Witten invariants of [C^3/Z_n], and provide extensive checks with predictions from open string mirror symmetry. To this aim we set up a computation of open string invariants in the spirit of Katz-Liu, defining them by localization. The orbifold is viewed as an open chart of a global quotient of the resolved conifold, and the Lagrangian as the fixed locus of an appropriate anti-holomorphic involution. We consider two main applications of the formalism. After warming up with the simpler example of [C^3/Z_3], where we verify physical predictions of Bouchard, Klemm, Marino and Pasquetti, the main object of our study is the richer case of [C^3/Z_4], where two different choices are allowed for the Lagrangian. For one choice, we make numerical checks to confirm the B-model predictions; for the other, we prove a mirror theorem for orbifold disc invariants, match a large number of annulus invariants, and give mirror symmetry predictions for open string invariants of genus \leq 2.Comment: 44 pages + appendices; v2: exposition improved, misprints corrected, version to appear on Selecta Mathematica; v3: last minute mistake found and fixed for the symmetric brane setup of [C^3/Z_4]; in pres

Photometric Properties of Six Local Volume Dwarf Galaxies from Deep Near-Infrared Observations

We have obtained deep near-infrared $J$- (1.25 $\mu$m), $H$- (1.65$\mu$m) and $K_s$-band (2.15 $\mu$m) imaging for a sample of six dwarf galaxies (M_B\ga-17 mag) in the Local Volume (LV, D\la10 Mpc). The sample consists mainly of early-type dwarf galaxies found in various environments in the LV. Two galaxies (LEDA 166099 and UGCA 200) in the sample are detected in the near-infrared for the first time. The deep near-infrared images allow for a detailed study of the photometric and structural properties of each galaxy. The surface brightness profiles of the galaxies are detected down to the ~$24 mag arcsec^{-2}$ isophote in the $J$- and $H$-bands, and $23 mag arcsec^{-2}$ in the $K_s$-band. The total magnitudes of the galaxies are derived in the three wavelength bands. For the brightest galaxies (M_B\la-15.5 mag) in the sample, we find that the Two Micron All Sky Survey (2MASS) underestimates the total magnitudes of these systems by up to \la0.5 mag. The radial surface brightness profiles of the galaxies are fitted with an exponential (for those galaxies having a stellar disk) or S\'ersic law to derive the structure of the underlying stellar component. In particular, the effective surface brightness ($\mu_e$) and effective radius ($r_e$) are determined from the analytic fits to the surface brightness profile. The $J$-$K_s$ colours for the galaxies have been measured to explore the luminosity-metallicity relation for early-type dwarfs. In addition, the $B$-$K_s$ colours of the galaxies are used to assess their evolutionary state relative to other galaxy morphologies. The total stellar masses of the dwarf galaxies are derived from the $H$-band photometric measurements. These will later be compared to the dynamical mass estimates for the galaxies to determine their dark matter content.Comment: 14 pages, 8 figures, submitted to MNRA