Bipasha Chakraborty

High-precision quark masses and QCD coupling from nf = 4 lattice QCD

We present a new lattice QCD analysis of heavy-quark pseudoscalar-pseudoscalar correlators, using gluon configurations from the MILC Collaboration that include vacuum polarization from u , d , s , and c quarks ( n f = 4 ). We extract new values for the QCD coupling and for the c quark’s MS ¯ mass: α MS ¯ ( M Z , n f = 5 ) = 0.11822 ( 74 ) and m c ( 3 GeV , n f = 4 ) = 0.9851 ( 63 ) GeV . These agree well with our earlier simulations using n f = 3 sea quarks, vindicating the perturbative treatment of c quarks in that analysis. We also obtain a new nonperturbative result for the ratio of c and s quark masses: m c / m s = 11.652 ( 65 ) . This ratio implies m s ( 2 GeV , n f = 3 ) = 93.6 ( 8 ) MeV when it is combined with our new c mass. Combining m c / m s with our earlier m b / m c gives m b / m s = 52.55 ( 55 ) , which is several standard deviations (but only 4%) away from the Georgi-Jarlskop prediction from certain grand unified theories. Finally we obtain an n f = 4 estimate for m b / m c = 4.528 ( 54 ) which agrees well with our earlier n f = 3 result. The new ratio implies m b ( m b , n f = 5 ) = 4.162 ( 48 ) GeV .

Lattice study of quark and glue momenta and angular momenta in the nucleon

We report a complete calculation of the quark and glue momenta and angular momenta in the proton. These include the quark contributions from both the connected and disconnected insertions. The quark disconnected insertion loops are computed with

The hadronic vacuum polarization contribution to

Z_4

a_{\mu}

noise, and the signal-to-noise is improved with unbiased subtractions. The glue operator is comprised of gauge-field tensors constructed from the overlap operator. The calculation is carried out on a

from full lattice QCD

16^3 \times 24

Estimate of the hadronic vacuum polarization disconnected contribution to the anomalous magnetic moment of the muon from lattice QCD

quenched lattice at

Quark and Glue Momenta and Angular Momenta in the Proton --- a Lattice Calculation

\beta = 6.0

Strong-Isospin-Breaking Correction to the Muon Anomalous Magnetic Moment from Lattice QCD at the Physical Point

for Wilson fermions with

The hadronic vacuum polarization contribution to a from full lattice QCD

\kappa=0.154, 0.155

Nonperturbative tests of the renormalisation of mixed clover-staggered currents in lattice QCD

, and