Quark mass dependence of pseudoscalar masses and decay constants

The dependence of the pseudoscalar meson masses and decay constants on sea and valence quark masses is compared to next-to-leading order (NLO) Chiral Perturbation Theory (ChPT). The numerical simulations with two light dynamical quark flavors are performed with the Wilson-quark lattice action at gauge coupling beta=5.1 and hopping parameters kappa=0.176, 0.1765, 0.177 on a 16^4 lattice. O(a) lattice artifacts are taken into account by applying chiral perturbation theory for t...

Our previous calculations of the sea- and valence-quark mass dependence of the pseudoscalar meson masses and decay constants is repeated on a 16^3x32 lattice which allows for a better determination of the quantities in question. The conclusions are similar as before on the 16^4 lattice [1]. The two light dynamical quark flavours we simulate have masses in the range 1/4 m_s < m_{u,d} < 2/3 m_s. The sea quark mass dependence of f_pi and m_pi^2/m_q is well described by the...

We present the latest preliminary results of the MILC collaboration's analysis of the light pseudoscalar meson sector. The analysis includes data from new ensembles with smaller lattice spacings, smaller light quark masses and lighter-than-physical strange quark masses. Both SU(2) and SU(3) chiral fits, including NNLO chiral logarithms, are shown. We give results for decay constants, quark masses, Gasser-Leutwyler low energy constants, and condensates in the two- and three-fl...

Due to improvements in computer performance and algorithms, the rapidly increasing cost for unquenched Wilson-type fermions with lighter quarks has been ameliorated and new simulations are now possible. Here we present results using two flavours of O(a)-improved Wilson fermions for meson decay constants at pseudoscalar masses down to 320MeV. Results are at several lattice spacings down to about 0.07fm and include a non-perturbative determination of the renormalisation constan...

This paper presents a first study of the masses and decay constants of the charged, or flavor-off-diagonal, pseudoscalar mesons to two loops for two flavors of sea-quarks, in Partially Quenched Chiral Perturbation Theory (PQ$\chi$PT). Explicit analytical expressions up to ${\cal O}(p^6)$ in the momentum expansion are given. The calculations have been performed within the supersymmetric formulation of PQ$\chi$PT. A numerical analysis is done to indicate the size of the correct...

As part of our program of lattice simulations of three flavor QCD with improved staggered quarks, we have calculated pseudoscalar meson masses and decay constants for a range of valence quark masses and sea quark masses on lattices with lattice spacings of about 0.125 fm and 0.09 fm. We fit the lattice data to forms computed with staggered chiral perturbation theory. Our results provide a sensitive test of the lattice simulations, and especially of the chiral behavior, includ...

We calculate various properties of pseudoscalar mesons in partially quenched QCD using chiral perturbation theory through next-to-leading order. Our results can be used to extrapolate to QCD from partially quenched simulations, as long as the latter use three light dynamical quarks. In other words, one can use unphysical simulations to extract physical quantities - in this case the quark masses, meson decay constants, and the Gasser-Leutwyler parameters L_4-L_8. Our proposal ...

I review recent lattice QCD results on light hadron spectroscopy and pseudoscalar decay constants.

We explore sea quark effects in the light hadron mass spectrum in a simulation of two-flavor QCD using the nonperturbatively O(a)-improved Wilson fermion action. In order to identify finite-size effects, light meson masses are measured on 12^3x48, 16^3x48 and 20^3x48 lattices with a~0.1 fm. On the largest lattice, where the finite-size effect is negligible, we find a significant increase of the strange vector meson mass compared to the quenched approximation. We also investig...

This paper summarizes the recent calculations of the masses and decay constants of the pseudoscalar mesons at the two-loop level, or NNLO, in Partially Quenched Chiral Perturbation Theory (PQxPT). Possible applications include chiral extrapolations of Lattice QCD, as well as the determination of the low-energy constants (LEC:s) of QCD.