arXiv subjects
Publications and source records attributed to Jon-Ivar Skullerud.
A new method for computing all elements of the lattice quark propagator is proposed. The method combines the spectral decomposition of the propagator, computing the lowest eigenmodes exactly, with noisy estimators which are 'diluted', i.e. taken to have support only on a subset of time, space, spin or colour. We find that the errors are dramatically reduced compared to traditional noisy estimator techniques.
The static-light matrix element needed to determine $f_B$ is studied on an anisotropic lattice with $N_f=2$. The improvement in precision due to stout links and all-to-all propagators is investigated.
We present a new exact algorithm for estimating all elements of the quark propagator. The advantage of the method is that the exact all-to-all propagator is reproduced in a large but finite number of inversions. The efficacy of the algorithm is tested in Monte Carlo simulations of Wilson quarks in quenched QCD. Applications that are difficult to probe with point propagators are discussed.
We compute the quark-gluon vertex in quenched lattice QCD, in the Landau gauge using an off-shell mean-field O(a)-improved fermion action. The complete vertex is computed in two specific kinematical limits, while the Dirac-vector part is computed for arbitrary kinematics. We find a nontrivial and rich tensor structure, including a substantial infrared enhancement of the interaction strength regardless of kinematics.
We report on the status of our simulations of two-colour QCD with two flavours of Wilson quarks, at nonzero chemical potential and diquark source. Preliminary results are presented for the static quark potential, gluon propagator, and meson and diquark spectrum.
The classical approximation may be applied to a number of problems in non-equilibrium field theory. The principles and limits of classical real-time lattice simulations are presented, with particular emphasis on the definition of particle numbers and energies and on applications to the earliest stages of heavy-ion collisions.
We consider the out-of-equilibrium (quasi-) particle number distributions of the Higgs and W-fields during electroweak tachyonic preheating. We model this process by a fast quench, and perform classical real-time lattice simulations in the SU(2)-Higgs model in three dimensions. We discuss how to define particle numbers and effective energies using two-point functions in Coulomb and unitary gauge, and consider some of the associated problems. After an initial exponential growth in effective particle numbers, the system stabilises, allowing us to extract effective masses, temperatures and chemical potentials for the particles.
We study out-of-equilibrium quasi-particle distributions of the Higgs and W fields during the zero-temperature tachyonic electroweak transition that has been assumed in recent scenarios of baryogenesis. Approximating the process by a fast quench, we perform classical real-time lattice simulations in the SU(2)-Higgs model. The emerging quasi-particle numbers and energies are then used to determine the effective temperatures, chemical potentials and masses of the particles shortly after the transition.