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In calculations of the hyperfine splitting in charmonium, the contributions of the disconnected diagrams are considered small and are typically ignored. We aim to estimate nonperturbatively the size of the resulting correction, which may eventually be needed in high precision calculations of the charmonium spectrum. We study this problem in the quenched and unquenched QCD cases. On dynamical ensembles the disconnected charmonium propagators contain light modes which complicate the extraction of the signal at large distances. In the fully quenched case, where there are no such light modes, the interpretation of the signal is simplified. We present results from lattices with a ≈ 0.09??fm and a ≈ 0.06??fm. [ABSTRACT FROM AUTHOR]

In a study using a non-serological enzymatic approach for the detection of Neisseria gonorrhoeae in cervical and urethral swabs, the technique was shown to be technically feasible. The enzyme, 1, 2-propanediol oxidoreductase, was used as a presumptive diagnostic marker for N gonorrhoeae. Enzymatic activity was measured with a fluorometer. Two assay procedures were performed: (a) enzyme detection (two-tube and three-tube assays) requiring 60 minutes; and (b) enzyme inhibition (EI) (90-minute and modified 20-minute assays). Sensitivities of the two-tube, three-tube, and the 90-minute EI assays with male urethral specimens from a high-prevalence population were 80%, 84%, and 91% respectively. The specificities of these assays in a low-prevalence male population were not determined. Sensitivity of the 90-minute EI assay in a high-prevalence female group was 77% and specificity in a low-prevalence female group was 75%. The modified EI assay was tested only in a low-prevalence female group and had 87% specificity. Although the specificity of the assays needs improvement, several advantages--including early case detection, rapid availability of results, detection of current active infections, and the possibility of automation--are intrinsic in this enzymatic approach. [ABSTRACT FROM PUBLISHER]

We calculate the contribution to the muon anomalous magnetic moment hadronic vacuum polarization from the connected diagrams of up and down quarks, omitting electromagnetism. We employ QCD gauge-field configurations with dynamical u, d, s, and c quarks and the physical pion mass, and analyze five ensembles with lattice spacings ranging from a≈0.06 to 0.15 fm. The up- and down-quark masses in our simulations have equal masses ml. We obtain, in this world where all pions have the mass of the π0, 1010allμ(conn.)=637.8(8.8), in agreement with independent lattice-QCD calculations. We then combine this value with published lattice-QCD results for the connected contributions from strange, charm, and bottom quarks, and an estimate of the uncertainty due to the fact that our calculation does not include strong-isospin breaking, electromagnetism, or contributions from quark-disconnected diagrams. Our final result for the total O(α²) hadronic-vacuum polarization to the muon's anomalous magnetic moment is 1010aHVP,LOμ=699(15)u,d(1)s,c,b, where the errors are from the light-quark and heavy-quark contributions, respectively. Our result agrees with both ab-initio lattice-QCD calculations and phenomenological determinations from experimental e+e--scattering data. It is 1.3σ below the "no new physics" value of the hadronic-vacuum-polarization contribution inferred from combining the BNL E821 measurement of aμ with theoretical calculations of the other contributions. [ABSTRACT FROM AUTHOR]

Preliminary results from the MILC collaboration for ƒB, ƒB, ƒD, ƒDand their ratios are presented. We compute in the quenched approximation at β = 6.3, 6.0 and 5.7 with Wilson light quarks and static and Wilson heavy quarks. We attempt to quantify all systematic errors other than quenching.

We present results from studies of high temperature QCD with two flavors of Kogut-Susskind quarks on 163× 8 lattices at a quark mass of amq= 0.00625 and on 243× 12 lattices at quark masses amq= 0.008 and 0.016. The value of the crossover temperature is consistent with that obtained on coarser lattices and/or at larger quark masses. Results are presented for the chiral order parameter and for the baryon number susceptibility.

We present results for the equation of state in (2 + l)-flavor QCD using the highly improved staggered quark action and lattices with temporal extent Nτ = 6, 8, 10, and 12. We show that these data can be reliably extrapolated to the continuum limit and obtain a number of thermodynamic quantities and the speed of sound in the temperature range 130-400 MeV. We compare our results with previous calculations and provide an analytic parameterization of the pressure, from which other thermodynamic quantities can be calculated, for use in phenomenology. We show that the energy density in the crossover region, 145 MeV ≤ T ≤ 163 MeV, defined by the chiral transition, is lc = (0.18-0.5) GeV/fm³, i.e., (1.2-3.1) lnucIear. At high temperatures, we compare our results with resummed and dimensionally reduced perturbation theory calculations. As a byproduct of our analyses, we obtain the values of the scale parameters r0 from the static quark potential and w0 from the gradient flow. [ABSTRACT FROM AUTHOR]

We have continued our study of the phase diagram of high temperature QCD with three flavors of improved staggered quarks. We are performing simulations with three degenerate quarks with masses less than or equal to the strange quark mass m s and with denegerate up and down quarks with masses m u,d decreases, rather than a bona fide phase transition. We present new results for the crossover temperature extrapolated to the physical value of m u,d and for quark number susceptibilities. [Copyright &y& Elsevier]

Starting in 2001, the MILC Collaboration began a large scale calculation of heavy-light meson decay constants using clover valence quarks on esembles of three flavor configurations. For the coarse configurations, with , eight combinations of dynamical light and strange quarks have been analyzed. For the fine configurations, with , three combinations of quark masses are studied. Since we last reported on this calculation, statistics have been increased on the fine ensembles, and, more importantly, a preliminary value fir the perturbative renormalization of the axial-vector current has become available. Thus, results for , , and can, in principle, be calculated in MeV, in addition to decay-constant ratios that were calculated previously. [Copyright &y& Elsevier]

We compute pseudoscalar meson masses and decay constants in partially quenched QCD with three dynamical flavors of improved staggered quarks. Fitting the lattice data to staggered chiral perturbation theory (SχPT) forms and extrapolating in quark mass and lattice spacing, we find: , , and . The value for implies . We also obtain , or, with more input on electromagnetic (EM) effects from the continuum, . Using the one-loop perturbative mass renormalization [Phys. Rev. D 70 (2004) 031504(R)], we determine m u and m d in the MS scheme. [Copyright &y& Elsevier]

We compute pseudoscalar meson masses and decay constants using staggered quarks on lattices with three flavors of sea quarks and lattice spacing ≈ 0.12 fm and ≈ 0.09 fm. We fit partially quenched results to “staggered chiral perturbation theory” formulae, thereby taking into account the effects of taste-symmetry violations. Chiral logarithms are observed. From the fits we calculate fπ and fϰ, extract Gasser-Leutwyler parameters of the chiral Lagrangian, and (modulo rather large perturbative errors) find the light and strange quark masses. [Copyright &y& Elsevier]

We summarize our measurement of the mass of the exotic 1−+ hybrid meson using an improved Kogut-Susskind action. We show results from both quenched and dynamical quark simulations and compare with results from Wilson quarks. Extrapolation of these results to the physical quark mass allows comparison with experimental candidates for the 1−+ hybrid meson. [Copyright &y& Elsevier]

We compute chiral logarithms in the presence of “taste” symmetry breaking of staggered fermions. The lagrangian of Lee and Sharpe is generalized and then used to calculate the logs in π and K masses. We correct an error in Ref. [1]. MILC data with three light dynamical flavors can be well fit by our formulas. However, two new chiral parameters, which describe O(a2) hairpin diagrams for taste-nonsinglet mesons, enter in the fits. To obtain precise results for the physical O(p4) coefficients, these new parameters will need to be bounded. [Copyright &y& Elsevier]

We use lattice QCD to calculate the form factors f+ (q²) and f0 (q²) for the semileptonic decay Bs → Kℓν. Our calculation uses six MILC asqtad 2 + 1 flavor gauge-field ensembles with three lattice spacings. At the smallest and largest lattice spacing the light-quark sea mass is set to 1 / 10 the strange-quark mass. At the intermediate lattice spacing, we use four values for the light-quark sea mass ranging from 1/5 to 1/20 of the strange-quark mass. We use the asqtad improved staggered action for the light valence quarks, and the clover action with the Fermilab interpolation for the heavy valence bottom quark. We use SU(2) hard-kaon heavy-meson rooted staggered chiral perturbation theory to take the chiral-continuum limit. A functional z expansion is used to extend the form factors to the full kinematic range. We present predictions for the differential decay rate for both Bs → Kμν and Bs → Kτν. We also present results for the forward-backward asymmetry, the lepton polarization asymmetry, ratios of the scalar and vector form factors for the decays Bs → Kℓν and Bs → Dsℓν. Our results, together with future experimental measurements, can be used to determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |Vub|. [ABSTRACT FROM AUTHOR]

Using highly improved staggered quark (HISQ) Nf = 2 + 1 + 1 MILC ensembles with five different values of the lattice spacing, including four ensembles with physical quark masses, we perform the most precise computation to date of the K → πℓν vector form factor at zero momentum transfer, f+K0π- (0) = 0.9696 (15)stat (12)syst. This is the first calculation that includes the dominant finite-volume effects, as calculated in chiral perturbation theory at next-to-leading order. Our result for the form factor provides a direct determination of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |Vus| = 0.22333(44)f+(0) (42)exp, with a theory error that is, for the first time, at the same level as the experimental error. The uncertainty of the semileptonic determination is now similar to that from leptonic decays and the ratio fK+/fπ+, which uses |Vud| as input. Our value of |Vus| is in tension at the 2-2.6σ level both with the determinations from leptonic decays and with the unitarity of the CKM matrix. In the test of CKM unitarity in the first row, the current limiting factor is the error in |Vud|, although a recent determination of the nucleus-independent radiative corrections to superallowed nuclear β decays could reduce the |Vud|² uncertainty nearly to that of |Vus|². Alternative unitarity tests using only kaon decays, for which improvements in the theory and experimental inputs are likely in the next few years, reveal similar tensions and could be further improved by taking correlations between the theory inputs. As part of our analysis, we calculated the correction to f+Kπ(0) due to nonequilibrated topological charge at leading order in chiral perturbation theory, for both the full-QCD and the partially quenched cases. We also obtain the combination of low-energy constants in the chiral effective Lagrangian [C12r + C34r - (L5r)²] (Mρ) = (2.92 ± 0.31) × 10-6. [ABSTRACT FROM AUTHOR]

We compute the leptonic decay constants fD+, fDs, and fK+ and the quark-mass ratios mc/ms and ms/ml in unquenched lattice QCD using the experimentally determined value of fπ+ for normalization. We use the MILC highly improved staggered quark ensembles with four dynamical quark flavors--up, down, strange, and charm--and with both physical and unphysical values of the light sea-quark masses. The use of physical pions removes the need for a chiral extrapolation, thereby eliminating a significant source of uncertainty in previous calculations. Four different lattice spacings ranging from a ≈ 0.06 to 0.15 fm are included in the analysis to control the extrapolation to the continuum limit. Our primary results are fD+ = 212.6(0.4)(+1.0-1.2) MeV, fDs = 249.0(0.3)(+1.1-1.5) MeV, and fDs/fD+ = 1.1712(10)(+29-32), where the errors are statistical and total systematic, respectively. The errors on our results for the charm decay constants and their ratio are approximately 2-4 times smaller than those of the most precise previous lattice calculations. We also obtain fK+/fπ+ = 1.1956(10)(+26-18), updating our previous result, and determine the quark-mass ratios ms/ml = 27.35(5)(+10-7) and mc/ms = 11.747(19)(+59-43). When combined with experimental measurements of the decay rates, our results lead to precise determinations of the Cabibbo-Kobayashi-Maskawa matrix elements |Vus| = 0.22487(51)(29)(20)(5), |Vcd| = 0.217(1)(5)(1) and |Vcs| = 1.010(5)(18)(6), where the errors are from this calculation of the decay constants, the uncertainty in the experimental decay rates, structure-dependent electromagnetic corrections, and, in the case of |Vus|, the uncertainty in |Vud|, respectively. [ABSTRACT FROM AUTHOR]

We compute the zero-recoil form factor for the semileptonic decay &Bmacr; → D*ℓv (and modes related by isospin and charge conjugation) using lattice QCD with three flavors of sea quarks. We use an improved staggered action for the light valence and sea quarks (the MILC asqtad configurations), and the Fermilab action for the heavy quarks. Our calculations incorporate higher statistics, finer lattice spacings, and lighter quark masses than our 2008 work. As a byproduct of tuning the new data set, we obtain the Ds and Bs hyperfine splittings with few-MeV accuracy. For the zero-recoil form factor, we obtain F(1) = 0.906(4)(12), where the first error is statistical and the second is the sum in quadrature of all systematic errors. With the latest Heavy Flavor Averaging Group average of experimental results and a cautious treatment of QED effects, we find |Vcb|=(39.04±0.49expt±0.53QCD±0.19QED)× 10-3. The QCD error is now commensurate with the experimental error. [ABSTRACT FROM AUTHOR]

Using staggered fermions and partially twisted boundary conditions, we calculate the K meson semileptonic decay vector form factor at zero momentum transfer. The highly improved staggered quark formulation is used for the valence quarks, while the sea quarks are simulated with the asqtad action (MILC Collaboration Nf=2+1 configurations). For the chiral and continuum extrapolation, we use two-loop continuum χPT, supplemented by partially quenched staggered χPT at one loop. Our result is f+Kπ(0)=0.9667±0.0023±0.0033, where the first error is statistical and the second is the sum in quadrature of the systematic uncertainties. This result is the first Nf=2+1 calculation with two lattice spacings and a controlled continuum extrapolation. It is also the most precise result to date for the vector form factor, and, although the central value is larger than previous unquenched lattice calculations, it is compatible with them within errors. Combining our value for f+Kπ(0) with the latest experimental measurements of K semileptonic decays, we obtain ∣Vus∣=0.2238±0.0009±0.0005, where the first error is from f+Kπ(0) and the second one is experimental. As a byproduct of our calculation, we obtain the combination of low-energy constants (C12r+C34r-(L5r)²)(Mρ)=(3.62±1.00)×10-6. [ABSTRACT FROM AUTHOR]

We present results from our simulations of quantum chromodynamics with four flavors of quarks: u, d, s, and c. These simulations are performed with a one-loop Symanzik improved gauge action and the highly improved staggered quark action. We are generating gauge configurations with four values of the lattice spacing ranging from 0.06 to 0.15 fm, and three values of the light quark mass, including the value for which the Goldstone pion mass is equal to the physical pion mass. We discuss simulation algorithms, scale setting, taste symmetry breaking, and the autocorrelations of various quantities. We also present results for the topological susceptibility that demonstrate the improvement of the highly improved staggered quark configurations relative to those generated earlier with the asqtad improved staggered action. [ABSTRACT FROM AUTHOR]

As one test of the validity of the staggered-fermion fourth-root determinant trick, we examine the suppression of the topological suspectibility of the QCD vacuum in the limit of small quark mass. The suppression is sensitive to the number of light sea quark flavors. Our study is done in the presence of 2+1 flavors of dynamical quarks in the improved staggered fermion formulation. Variance-reduction techniques provide better control of statistical errors. New results from staggered chiral perturbation theory account for taste-breaking effects in the low-quark mass behavior of the susceptibility, thereby reducing scaling violations from this source. Measurements over a range of quark masses at two lattice spacings permit a rough continuum extrapolation to remove the remaining lattice artifacts. The results are consistent with chiral perturbation theory with the correct flavor counting. [Copyright &y& Elsevier]

We present results for form factors of semileptonic decays of D and B mesons in flavor lattice QCD using the MILC gauge configurations. With an improved staggered action for light quarks, we successfully reduce the systematic error from the chiral extrapolation. The results for D decays are in agreement with experimental ones. The results for B decays are preliminary. Combining our results with experimental branching ratios, we then obtain the CKM matrix elements , , and . We also check CKM unitarity, for the first time, using only lattice QCD as the theoretical input. [Copyright &y& Elsevier]

Abstract: We determine the leptonic decay constants and in three flavor unquenched lattice QCD. We use -improved sraggered light quarks and -improved charm quarks in the Fermilab heavy quark formalism. Our preliminary results, based upon an analysis at a single lattice spacing, are and . In each case, the first reported error is statistical while the second is the combined systematic uncertainty. [Copyright &y& Elsevier]

Preliminary results from simulations with 2+1 dynamical quark flavors at a lattice spacing of 0.09 fm are combined with earlier results at a = 0.13 fm. We examine the approach to the continuum limit and investigate the dependence of the pseudoscalar masses and decay constants as the sea and valence quark masses are separately varied. [Copyright &y& Elsevier]

We present preliminary results for the heavy-light leptonic decay constants in the presence of three light dynamical flavors. We generate dynamical configurations with improved staggered and gauge actions and analyze them for heavy-light physics with tadpole improved clover valence quarks. When the scale is set by mρ, we find an increase of ≈23% in fB with three dynamical flavors over the quenched case. Discretization errors appear to be small (≲3%) in the quenched case but have not yet been measured in the dynamical case. [Copyright &y& Elsevier]

We present a lattice calculation of the electromagnetic (EM) effects on the masses of light pseudoscalar mesons. The simulations employ 2+1 dynamical flavors of asqtad QCD quarks and quenched photons. Lattice spacings vary from ≈0.12 fm to ≈0.045 fm. We compute the quantity ε, which parametrizes the corrections to Dashen's theorem for the K+-K0 EM mass splitting, as well as εK0, which parametrizes the EM contribution to the mass of the K0 itself. An extension of the nonperturbative EM renormalization scheme introduced by the BMW group is used in separating EM effects from isospin-violating quark mass effects. We correct for leading finite-volume effects in our realization of lattice electrodynamics in chiral perturbation theory, and remaining finite-volume errors are relatively small. While electroquenched effects are under control for ε, they are estimated only qualitatively for εK0 and constitute one of the largest sources of uncertainty for that quantity. We find ε=0.78(1)stat(+8-11)syst and εK0=0.035(3)stat(20)syst. We then use these results on 2+1+1 flavor pure QCD highly improved staggered quark (HISQ) ensembles and find mu/md=0.4529(48)stat(+150-67)syst. [ABSTRACT FROM AUTHOR]

We calculate the leptonic decay constants of heavy-light pseudoscalar mesons with charm and bottom quarks in lattice quantum chromodynamics on four-flavor QCD gauge-field configurations with dynamical u, d, s, and c quarks. We analyze over twenty isospin-symmetric ensembles with six lattice spacings down to a≈0.03 fm and several values of the light-quark mass down to the physical value 1/2(mu+md). We employ the highly-improved staggered-quark (HISQ) action for the sea and valence quarks; on the finest lattice spacings, discretization errors are sufficiently small that we can calculate the B-meson decay constants with the HISQ action for the first time directly at the physical b-quark mass. We obtain the most precise determinations to-date of the D- and B-meson decay constants and their ratios, fD+=212.7(0.6) MeV, fDs=249.9(0.4) MeV, fDs/fD+=1.1749(16), fB+=189.4(1.4) MeV, fBs=230.7(1.3) MeV, fBs/fB+=1.2180(47), where the errors include statistical and all systematic uncertainties. Our results for the B¯meson decay constants are three times more precise than the previous best lattice-QCD calculations, and bring the QCD errors in the standard model predictions for the rare leptonic decays ¯B(Bs→μ+μ-)=3.64(11)×10-9, ¯B(B0→μ+μ-)=1.00(3)×10-11, and ¯B(B0→μ+μ-)/¯B(Bs→μ+μ-)=0.00264(8) to well below other sources of uncertainty. As a byproduct of our analysis, we also update our previously published results for the light-quark-mass ratios and the scale-setting quantities fp4s, Mp4s, and Rp4s. We obtain the most precise lattice-QCD determination to date of the ratio fK+/fπ+=1.1950(+16-23) MeV. [ABSTRACT FROM AUTHOR]

We calculate the up-, down-, strange-, charm-, and bottom-quark masses using the MILC highly improved staggered-quark ensembles with four flavors of dynamical quarks. We use ensembles at six lattice spacings ranging from a≈0.15 to 0.03 fm and with both physical and unphysical values of the two light and the strange sea-quark masses. We use a new method based on heavy-quark effective theory (HQET) to extract quark masses from heavy-light pseudoscalar meson masses. Combining our analysis with our separate determination of ratios of light-quark masses we present masses of the up, down, strange, charm, and bottom quarks. Our results for the MS-renormalized masses are mu(2 GeV)=2.130(41) MeV, md(2 GeV)=4.675(56) MeV, ms(2 GeV)=92.47(69) MeV, mc(3 GeV)=983.7(5.6) MeV, and mc(mc)=1273(10) MeV, with four active flavors; and mb(mb)=4195(14) MeV with five active flavors. We also obtain ratios of quark masses mc/ms=11.783(25), mb/ms=53.94(12), and mb/mc=4.578(8). The result for mc matches the precision of the most precise calculation to date, and the other masses and all quoted ratios are the most precise to date. Moreover, these results are the first with a perturbative accuracy of α4s. As byproducts of our method, we obtain the matrix elements of HQET operators with dimension 4 and 5: ΛMRS=555(31) MeV in the minimal renormalon-subtracted (MRS) scheme, μ²π=0.05(22) GeV², and μ²G(mb)=0.38(2) GeV². The MRS scheme [Phys. Rev. D 97, 034503 (2018)] is the key new aspect of our method. [ABSTRACT FROM AUTHOR]

We calculate in three-flavor lattice QCD the short-distance hadronic matrix elements of all five ΔC=2 four-fermion operators that contribute to neutral D-meson mixing both in and beyond the Standard Model. We use the MILC Collaboration's Nf=2+1 lattice gauge-field configurations generated with asqtad-improved staggered sea quarks. We also employ the asqtad action for the valence light quarks and use the clover action with the Fermilab interpretation for the charm quark. We analyze a large set of ensembles with pions as light as Mπ≈180 MeV and lattice spacings as fine as a≈0.045 fm, thereby enabling good control over the extrapolation to the physical pion mass and continuum limit. We obtain for the matrix elements in the MS-NDR scheme using the choice of evanescent operators proposed by Beneke et al., evaluated at 3 GeV, ⟨D0|Oi|D0⟩={0.0805(55)(16),-0.1561(70)(31),0.0464(31)(9),0.2747(129)(55),0.1035(71)(21)} GeV4 (i=1-5). The errors shown are from statistics and lattice systematics, and the omission of charmed sea quarks, respectively. To illustrate the utility of our matrix-element results, we place bounds on the scale of CP-violating new physics in D0 mixing, finding lower limits of about 10-50×10³ TeV for couplings of O(1). To enable our results to be employed in more sophisticated or model-specific phenomenological studies, we provide the correlations among our matrix-element results. For convenience, we also present numerical results in the other commonly used scheme of Buras, Misiak, and Urban. [ABSTRACT FROM AUTHOR]

Dramatic progress has been made over the last decade in the numerical study of quantum chromodynamics (QCD) through the use of improved formulations of QCD on the lattice (improved actions), the development of new algorithms, and the rapid increase in computing power available to lattice gauge theorists. In this article simulations of full QCD are described using the improved staggered quark formalism, "asqtad" fermions. These simulations were carried out with two degenerate flavors of light quarks (up and down) and with one heavier flavor, the strange quark. Several light quark masses, down to about three times the physical light quark mass, and six lattice spacings have been used. These enable controlled continuum and chiral extrapolations of many low energy QCD observables. The improved staggered formalism is reviewed, emphasizing both advantages and drawbacks. In particular, the procedure for removing unwanted staggered species in the continuum limit is reviewed. Then the asqtad lattice ensembles created by the MILC Collaboration are described. All MILC lattice ensembles are publicly available, and they have been used extensively by a number of lattice gauge theory groups. The physics results obtained with them are reviewed, and the impact of these results on phenomenology is discussed. Topics include the heavy quark potential, spectrum of light hadrons, quark masses, decay constants of light and heavy-light pseudoscalar mesons, semileptonic form factors, nucleon structure, scattering lengths, and more. [ABSTRACT FROM AUTHOR]