Justus Tobias Tsang

Calculation of the hadronic vacuum polarization contribution to the muon anomalous magnetic moment

We present a first-principles lattice QCD+QED calculation at physical pion mass of the leading-order hadronic vacuum polarization contribution to the muon anomalous magnetic moment. The total contribution of up, down, strange, and charm quarks including QED and strong isospin breaking effects is a_{μ}^{HVP LO}=715.4(18.7)×10^{-10}. By supplementing lattice data for very short and long distances with R-ratio data, we significantly improve the precision to a_{μ}^{HVP LO}=692.5(2.7)×10^{-10}. This is the currently most precise determination of a_{μ}^{HVP LO}.

Improved lattice fermion action for heavy quarks

A bstractWe develop an improved lattice action for heavy quarks based on Brillouintype fermions, that have excellent energy-momentum dispersion relation. The leading discretization errors of O(a) and O(a2) are eliminated at tree-level. We carry out a scaling study of this improved Brillouin fermion action on quenched lattices by calculating the charmonium energy-momentum dispersion relation and hyperfine splitting. We present a comparison to standard Wilson fermions and domain-wall fermions.

Charm physics with physical light and strange quarks using domain wall fermions

We present a study of charm physics using RBC/UKQCD 2+1 flavour physical point domain wall fermion ensembles for the light quarks as well as for the valence charm quark. After a brief motivation of domain wall fermions as a suitable heavy quark discretisation we will show first results for masses and matrix elements.

Domain Wall Charm Physics with Physical Pion Masses: Decay Constants, Bag and

We provide an overview of RBC/UKQCD’s charm project on 2+1 flavour physical pion mass ensembles using Mobius Domain Wall Fermions for the light as well as for the charm quark. We discuss the analysis strategy in detail and present results at the different stages of the analysis for D and Ds decay constants as well as the bag and x parameters. We also discuss future approaches to extend the reach in the heavy quark mass.

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A bstractWe report on an exploratory study of domain wall fermions (DWF) as a lattice regularisation for heavy quarks. Within the framework of quenched QCD with the tree-level improved Symanzik gauge action we identify the DWF parameters which minimise discretisation effects. We find the corresponding effective 4d overlap operator to be exponentially local, independent of the quark mass. We determine a maximum bare heavy quark mass of amh ≈ 0.4, below which the approximate chiral symmetry and O(a)-improvement of DWF are sustained. This threshold appears to be largely independent of the lattice spacing. Based on these findings, we carried out a detailed scaling study for the heavy-strange meson dispersion relation and decay constant on four ensembles with lattice spacings in the range 2.0-5.7 GeV. We observe very mild a2 scaling towards the continuum limit. Our findings establish a sound basis for heavy DWF in dynamical simulations of lattice QCD with relevance to Standard Model phenomenology.

Parameters

We present a progress update on the RBC-UKQCD calculation of beyond the standard model (BSM) kaon mixing matrix elements at the physical point. Simulations are performed using 2+1 flavour domain wall lattice QCD with the Iwasaki gauge action at 3 lattice spacings and with pion masses ranging from 430 MeV to the physical pion mass.

An exploratory study of heavy domain wall fermions on the lattice

We present scaling studies for heavy-quark observables calculated with an

BSM Kaon Mixing at the Physical Point

O(a^2)

Scaling study of an improved fermion action on quenched lattices

-improved fermion action on tree-level Symanzik improved gauge configurations. Lattices of

Progress in the calculation of purely leptonic

1/a =