We review simulations of dynamical domain wall fermions at a fixed inverse lattice spacing of 1.73GeV and with pion masses as light as 330MeV and spatial dimensions as large as 2.7fm performed by the RBC and UKQCD collaborations. These results include pseudoscalar masses and decay constants and low energy constants of the chiral effective lagrangian. We also review results for the neutral kaon mixing amplitude B K , the Kl3 form factor, pseudoscalar meson structure, and vector meson decay constants. In the baryon sector we review results for the spectrum, and nucleon form factors and structure functions. Highlights of our programme include preliminary quark masses, and determinations of V us from both f K / f π and from Kl3, and an updated result for B K. We find significant finite volume effects in the nucleon axial charge g A for our m π = 330 MeV ensemble on a (2.7fm) 3 lattice, and highlight the importance of large physical volumes for non-trivial nucleon physics.

We present a lattice QCD calculation of the ΔI ¼ 1=2, K → ππ decay amplitude A 0 and ε 0 , the measure of direct CP violation in K → ππ decay, improving our 2015 calculation [1] of these quantities. Both calculations were performed with physical kinematics on a 32 3 × 64 lattice with an inverse lattice spacing of a −1 ¼ 1.3784ð68Þ GeV. However, the current calculation includes nearly 4 times the statistics and numerous technical improvements allowing us to more reliably isolate the ππ ground state and more accurately relate the lattice operators to those defined in the standard model. We find ReðA 0 Þ ¼ 2.99ð0.32Þð0.59Þ × 10 −7 GeV and ImðA 0 Þ ¼ −6.98ð0.62Þð1.44Þ × 10 −11 GeV, where the errors are statistical and systematic, respectively. The former agrees well with the experimental result ReðA 0 Þ ¼ 3.3201ð18Þ × 10 −7 GeV. These results for A 0 can be combined with our earlier lattice calculation of A 2 [2] to obtain Reðε 0 =εÞ ¼ 21.7ð2.6Þð6.2Þð5.0Þ × 10 −4 , where the third error represents omitted isospin breaking effects, and ReðA 0 Þ=ReðA 2 Þ ¼ 19.9ð2.3Þð4.4Þ. The first agrees well with the experimental result of Reðε 0 =εÞ ¼ 16.6ð2.3Þ × 10 −4. A comparison of the second with the observed ratio ReðA 0 Þ=ReðA 2 Þ ¼ 22.45ð6Þ, demonstrates the standard model origin of this "ΔI ¼ 1=2 rule" enhancement.

In this proceedings we discuss the motivation, implementation details, and performance of a new physics code base called Grid. It is intended to be more performant, more general, but similar in spirit to QDP++ [6]. Our approach is to engineer the basic type system to be consistently fast, rather than bolt on a few optimised routines, and we are attempt to write all our optimised routines directly in the Grid framework. It is hoped this will deliver best known practice performance across the next generation of supercomputers, which will provide programming challenges to traditional scalar codes. We illustrate the programming patterns used to implement our goals, and advances in productivity that have been enabled by using new features in C++11.

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This paper presents two coupled software packages which receive widespread use in the field of numerical simulations of Quantum Chromo-Dynamics. These consist of the BAGEL library and the BAGEL Fermion sparse-matrix library, BFM.The Bagel library can generate assembly code for a number of architectures and is configurable -supporting several precision and memory pattern options to allow architecture specifig optimisation. It provides high performance on the QCDOC, BlueGene/L and BlueGene/P parallel computer architectures that are popular in the the field of lattice QCD. The code includes a complete conjugate gradient implementation for the Wilson and Domain Wall fermion actions, making it easy to use for third party codes including the Jefferson Laboratory's CHROMA, UKQCD's UKhadron, and the Riken-Brookhaven-Columbia collaboration's CPS packages.