UKQCD software for lattice quantum chromodynamics.

Quantum chromodynamics (QCD) is the quantum field theory of the strong nuclear interaction and it explains how quarks and gluons are bound together to make more familiar objects such as the proton and neutron, which form the nuclei of atoms. UKQCD is a collaboration of eight UK universities that have come together to obtain and pool sufficient resources, both computational and manpower, to perform lattice QCD calculations. This paper explains how UKQCD uses and develops this software, how performance critical kernels for diverse architectures such as quantum chromodynamics-on-a-chip, BlueGene and XT4 are developed and employed and how UKQCD collaborates both internally and externally, with, for instance, the US SciDAC lattice QCD community.

Building a scientific data grid with DiGS.

We provide an insight into the challenge of building and supporting a scientific data infrastructure with reference to our experience working with scientists from computational particle physics and molecular biology. We illustrate how, with modern high-performance computing resources, even small scientific groups can generate huge volumes (petabytes) of valuable scientific data and explain how grid technology can be used to manage, publish, share and curate these data. We describe the DiGS software application, which we have developed to meet the needs of smaller communities and we have highlighted the key elements of its functionality.

Kl3 semileptonic form factor from (2+1)-flavor lattice QCD.

We present the first results for the K13 form factor from simulations with 2+1 flavors of dynamical domain wall quarks. Combining our result, namely, f+(0)=0.964(5) with the latest experimental results for Kl3 decays leads to |V us|=0.

Neutral-kaon mixing from (2+1)-flavor domain-wall QCD.

We present the first results for neutral-kaon mixing using (2+1)-flavors of domain-wall fermions. A new approach is used to extrapolate to the physical up and down quark masses from our numerical studies with pion masses in the range 240-420 MeV; only SU(2)_{L}xSU(2)_{R} chiral symmetry is assumed and the kaon is not assumed to be light. Our main result is B_{K};{MS[over ]}(2 GeV)=0.

Simulation of the strong interaction.

In the Standard Model (SM) of particle physics, quarks are permanently confined by the strong interaction into bound states called hadrons. The values of some parameters, such as the quark masses and the strengths of the decays of one quark flavour into another, cannot be measured directly and must be deduced from experiments on hadrons. This requires calculations of the strong-interaction effects within the bound states, which are only possible using numerical simulations of quantum chromodynamics (QCD), the quantum field theory of the strong interaction.