Two-flavor QCD simulation with exact chiral symmetry

Abstract

We perform numerical simulations of lattice QCD with two flavors of dynamical overlap quarks, which have exact chiral symmetry on the lattice. While this fermion discretization is computationally demanding, we demonstrate the feasibility to simulate reasonably large and fine lattices by a careful choice of the lattice action and algorithmic improvements. Our production runs are carried out on a 16 3 × 32 lattice at a single lattice spacing around 0.12 fm. We explore the sea quark mass region down to m s /6, where m s is the physical strange quark mass, for a good control of the chiral extrapolation in future calculations of physical observables. We describe in detail our setup and algorithmic properties of the production simulations and present results for the static quark potential to fix the lattice scale and the locality of the overlap operator.

Topological susceptibility and axial symmetry at finite temperature

“…Accumulating the corresponding zero temperature configurations would have been a really demanding task so we do not have currently a measurement of the lattice spacing and pion mass for every β . At β = 2.30 and bare quark mass am = 0.015 was 286 MeV, 360 MeV at am = 0.025 [12]. By looking at the Dirac operator spectral density we observe that a gap is already opened at a temperature of around 192 MeV (β = 2.25) near the chiral limit, am = 0.01, confirmed by higher temperature simulations.…”

Flavor physics in the quark sector

“…Whatever one thinks of the rooted staggered sea, it should be clear that these calculations should be confirmed. Other methods for sea quarks are accumulating sufficiently high statistics, so one can anticipate competitive results not only with staggered sea quarks [106], but also with Symanzik-improved Wilson sea quarks [107,108], twistedmass Wilson sea quarks [109], domain-wall sea quarks [110], and overlap sea quarks [111].…”

Light meson physics from maximally twisted mass lattice QCD

“…The CDH formulae have a very similar form 5) where the I (i) m,f can be written in terms of basic integrals as discussed in ref. [65], where also m(n) is tabulated.…”

“…[1,2] for recent reviews). Simulations containing the dynamics of the light-quark flavours in the sea, as well as those due to the strange quark and recently also to the charm, using pseudo scalar masses below 300 MeV, spatial lattice extents L ≥ 2 fm and lattice spacings smaller than 0.1 fm are presently being performed by several lattice groups [3][4][5][6][7][8][9][10]. Such simulations will eventually allow for an extrapolation of the lattice data to the continuum limit and to the physical point while keeping also the finite volume effects under control.…”