28 research outputs found
Disconnected hadronic vacuum polarization contribution to the muon g-2 with HISQ
7 pages, 4 figures, The 36th Annual International Symposium on Lattice Field Theory - LATTICE2018We describe a computation of the contribution to the anomalous magnetic moment of the muon from the disconnected part of the hadronic vacuum polarization. We use the highly-improved staggered quark (HISQ) formulation for the current density with gauge configurations generated with four flavors of HISQ sea quarks. The computation is performed by stochastic estimation of the current density using the truncated solver method combined with deflation of low-modes. The parameters are tuned to minimize the computational cost for a given target uncertainty in the current-current correlation function. The calculation presented here is carried out on a single gauge-field ensemble of size with an approximate lattice spacing of fm and with physical sea-quark masses. We describe the methodology and the analysis procedur
Calculating the QED correction to the hadronic vacuum polarisation on the lattice
Isospin-breaking corrections to the hadron vacuum polarization component of the anomalous magnetic moment of the muon are needed to ensure the theoretical precision of gμ - 2 is below the experimental precision. We describe the status of our work calculating, using lattice QCD, the QED correction to the light and strange connected hadronic vacuum polarization in a Dashen scheme. We report results using physical N f = 2 + 1 + 1 HISQ ensembles at three lattice spacings and three heavier-than-light valence quark masses
Predictions from Lattice QCD
In the past year, we calculated with lattice QCD three quantities that were
unknown or poorly known. They are the dependence of the form factor in
semileptonic decay, the decay constant of the meson, and the
mass of the meson. In this talk, we summarize these calculations, with
emphasis on their (subsequent) confirmation by experiments.Comment: v1: talk given at the International Conference on QCD and Hadronic
Physics, Beijing, June 16-20, 2005; v2: poster presented at the XXIIIrd
International Symposium on Lattice Field Theory, Dublin, July 25-3
Hadronic-vacuum-polarization contribution to the muon's anomalous magnetic moment from four-flavor lattice QCD
19 pages, 12 figures, 6 tabesWe 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 , , , and quarks and the physical pion mass, and analyze five ensembles with lattice spacings ranging from a~0.06-0.15 fm. The up- and down-quark masses in our simulations have equal masses . We obtain, in this world where all pions have the mass of the , , 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. We obtain for the total order hadronic-vacuum polarization to the muon's anomalous magnetic moment , where the errors are from the light-quark connected contribution, heavy-flavor connected contributions, and omitted effects listed above, respectively. Our result agrees with both lattice-QCD calculations and phenomenological determinations from experimental -scattering data. It is 1.7 below the "no new physics" value of the hadronic-vacuum-polarization contribution inferred from combining the BNL E821 measurement of with theoretical calculations of the other contributions
Cosmic Flows on 100 Mpc/h Scales: Standardized Minimum Variance Bulk Flow, Shear and Octupole Moments
The low order moments, such as the bulk flow and shear, of the large scale
peculiar velocity field are sensitive probes of the matter density fluctuations
on very large scales. In practice, however, peculiar velocity surveys are
usually sparse and noisy, which can lead to the aliasing of small scale power
into what is meant to be a probe of the largest scales. Previously, we
developed an optimal ``minimum variance'' (MV) weighting scheme, designed to
overcome this problem by minimizing the difference between the measured bulk
flow (BF) and that which would be measured by an ideal survey. Here we extend
this MV analysis to include the shear and octupole moments, which are designed
to have almost no correlations between them so that they are virtually
orthogonal. We apply this MV analysis to a compilation of all major peculiar
velocity surveys, consisting of 4536 measurements. Our estimate of the BF on
scales of ~ 100 Mpc/h has a magnitude of |v|= 416 +/- 78 km/s towards Galactic
l = 282 degree +/- 11 degree and b = 6 degree +/- 6 degree. This result is in
disagreement with LCDM with WMAP5 cosmological parameters at a high confidence
level, but is in good agreement with our previous MV result without an
orthogonality constraint, showing that the shear and octupole moments did not
contaminate the previous BF measurement. The shear and octupole moments are
consistent with WMAP5 power spectrum, although the measurement noise is larger
for these moments than for the BF. The relatively low shear moments suggest
that the sources responsible for the BF are at large distances.Comment: 13 Pages, 7 figures, 4 tables. Some changes to reflect the published
versio