Stochastic locality and master-field simulations of very large lattices

In lattice QCD and other field theories with a mass gap, the field variables in distant regions of a physically large lattice are only weakly correlated. Accurate stochastic estimates of the expectation values of local observables may therefore be obtained from a single representative field. Such master-field simulations potentially allow very large lattices to be simulated, but require various conceptual and technical issues to be addressed. In this talk, an introduction to the subject is provided and some encouraging results of master-field simulations of the SU(3) gauge theory are reported.Comment: Talk given at the 35th International Symposium on Lattice Field Theory, 18-24 June 2017, Granada, Spain; LaTeX source with 6 figure

Simulations of QCD and QED with C* boundary conditions

We present exploratory results from dynamical simulations of QCD in isolation, as well as QCD coupled to QED, with C* boundary conditions. In finite volume, the use of C* boundary conditions allows for a gauge invariant and local formulation of QED without zero modes. In particular we show that the simulations reproduce known results and that masses of charged mesons can be extracted in a completely gauge invariant way. For the simulations we use a modified version of the HiRep code. The primary features of the simulation code are presented and we discuss some details regarding the implementation of C* boundary conditions and the simulated lattice action

Ergodicity of the LLR method for the Density of States

The LLR method is a novel algorithm that enables us to evaluate the density of states in lattice gauge theory. We present our study of the ergodicity properties of the LLR algorithm for the model of Yang-Mills SU(3). We show that the use of the replica exchange method alleviates significantly the topological freeze-out that severely affects other algorithms

Higgs compositeness in Sp(2N) gauge theories — The pure gauge model

As a first step in the study of Sp(2N) composite Higgs models, we obtained aset of novel numerical results for the pure gauge Sp(4) lattice theory in 3+1 space-timedimensions. Results for the continuum extrapolations of the string tension and the glueballmass spectrum are presented and their values are compared with the same quantitiesin neighbouring SU(N) models