Vincent Drach

Light hadrons from lattice QCD with light (u, d), strange and charm dynamical quarks

We present results of lattice QCD simulations with mass-degenerate up and down and mass-split strange and charm (Nf = 2 + 1 + 1) dynamical quarks using Wilson twisted mass fermions at maximal twist. The tuning of the strange and charm quark masses is performed at two values of the lattice spacing a ≈ 0:078 fm and a ≈ 0:086 fm with lattice sizes ranging from L ≈ 1:9 fm to L ≈ 2:8 fm. We measure with high statistical precision the light pseudoscalar mass mPS and decay constant fPS in a range 270 ≲ mPS ≲ 510 MeV and determine the low energy parameters f0 and

Computing K and D meson masses with N_f = 2+1+1 twisted mass lattice QCD

{\bar{l}_{3,4}}

Light baryon masses with dynamical twisted mass fermions

of SU(2) chiral perturbation theory. We use the two values of the lattice spacing, several lattice sizes as well as different values of the light, strange and charm quark masses to explore the systematic effects. A first study of discretisation effects in light-quark observables and a comparison to Nf = 2 results are performed.

Lattice calculation of parton distributions

We discuss the computation of the mass of the K and D mesons within the framework of N-f = 2 + 1 + 1 twisted mass lattice QCD from a technical point of view. These quantities are essential, already at the level of generating gauge configurations, being obvious candidates to tune the strange and charm quark masses to their physical values. In particular, we address the problems related to the twisted mass flavor and parity symmetry breaking, which arise when considering a non-degenerate (c, s) doublet. We propose and verify the consistency of three methods to extract the K and D meson masses in this framework. (c) 2010 Elsevier By. All rights reserved.

Light hadrons from Nf=2+1+1 dynamical twisted mass fermions

We present results on the mass of the nucleon and the

Low-lying baryon spectrum with two dynamical twisted mass fermions

\ensuremath{\Delta}

Disconnected quark loop contributions to nucleon observables in lattice QCD

using two dynamical degenerate twisted mass quarks and the tree-level Symanzik improved gauge action. The evaluation is performed at four quark masses corresponding to a pion mass in the range of about 300\char21{}600 MeV on lattices of 2.1\char21{}2.7 fm at three lattice spacings less than 0.1 fm. We check for cutoff effects by evaluating these baryon masses on lattices of spatial size 2.1 fm at

Computing K and D meson masses with N-f=2+1+1 twisted mass lattice QCD

\ensuremath{\beta}=3.9

Baryon spectrum with

and

N_f = 2 + 1 + 1

\ensuremath{\beta}=4.05