SearcharxivSearch

arXiv subjects

UKQCD collaborations

Publications and source records attributed to UKQCD collaborations.

4 recordsLinked to original sources

Domain wall QCD with physical quark masses

We present results for several light hadronic quantities ($f_π$, $f_K$, $B_K$, $m_{ud}$, $m_s$, $t_0^{1/2}$, $w_0$) obtained from simulations of 2+1 flavor domain wall lattice QCD with large physical volumes and nearly-physical pion masses at two lattice spacings. We perform a short, O(3)%, extrapolation in pion mass to the physical values by combining our new data in a simultaneous chiral/continuum `global fit' with a number of other ensembles with heavier pion masses. We use the physical values of $m_π$, $m_K$ and $m_Ω$ to determine the two quark masses and the scale - all other quantities are outputs from our simulations. We obtain results with sub-percent statistical errors and negligible chiral and finite-volume systematics for these light hadronic quantities, including: $f_π$ = 130.2(9) MeV; $f_K$ = 155.5(8) MeV; the average up/down quark mass and strange quark mass in the $\bar {\rm MS}$ scheme at 3 GeV, 2.997(49) and 81.64(1.17) MeV respectively; and the neutral kaon mixing parameter, $B_K$, in the RGI scheme, 0.750(15) and the $\bar{\rm MS}$ scheme at 3 GeV, 0.530(11).

hep-lat

Preliminary results of $ΔI=1/2$ and $3/2$, $K$ to $ππ$ Decay Amplitudes from Lattice QCD

We report a direct lattice calculation of the $K$ to $ππ$ decay matrix elements for both $ΔI=1/2$ and $3/2$ channels on 2+1 flavor, domain wall fermion, $16^3\times32$ lattices with zero $ππ$ relative momentum and $m_π=420$ MeV. All $K^0$ to $ππ$ contractions are carefully listed and calculated. The decay into the isospin zero $ππ$ final state, which receives contributions from the disconnected graphs, is very difficult to calculate, but a clear signal in the similar disconnected $ππ$ correlator can be seen. Preliminary results, some with large errors, will be presented for the various contributions to the renormalized weak matrix elements $A_0$ and $A_2$. We obtain Re$(A_0)$ with $25%$ error in the case of zero momentum on shell decay, and find a factor of 6 enhancement for the $ΔI=1/2$ rule in the $420$ MeV pion system.

hep-lat

Status of 2+1 flavor, 32^3x64 domain wall fermion simulations

We describe details of 1/a ~ 2.2Gev, L ~ 3 fm dynamical domain wall fermion simulations which will allow us to do a more systematic continuum extrapolation in combination with existing simu- lations. Details of the simulations such as algorithm choices and machine performance, as well as results of basic measurements are presented. These configurations are presently being generated on the QCDOC machine at Edinburgh and the DOE QCDOC machine at Brookhaven as part of a joint project with LHPC.

hep-lat