Light quark masses and pseudoscalar decay constants from Nf=2 Lattice QCD with twisted mass fermions

B. Blossier (1) , Ph. Boucaud (2) , P. Dimopoulos , F. Farchioni , R. Frezzotti , V. Gimenez , G. Herdoiza (2, 3) , K. Jansen (4) , V. Lubicz (5) , C. Michael , D. Palao , M. Papinutto , A. Shindler , S. Simula , C. Tarantino , C. Urbach , U. Wenger , Etm Collaboration

1 DESY - Deutsches Elektronen-Synchrotron [Zeuthen]
2 LPT - Laboratoire de Physique Théorique d'Orsay [Orsay]
3 Dipartimento de Fisica, Università degli studi di Roma II
4 NIC [Zeuthen]
5 INFN, Sezione di Roma 3 - Istituto Nazionale di Fisica Nucleare, Sezione di Roma 3

We present the results of a lattice QCD calculation of the average up-down and strange quark masses and of the light meson pseudoscalar decay constants with Nf=2 dynamical fermions. The simulation is carried out at a single value of the lattice spacing with the twisted mass fermionic action at maximal twist, which guarantees automatic O(a)-improvement of the physical quantities. Quark masses are renormalized by implementing the non-perturbative RI-MOM renormalization procedure. Our results for the light quark masses are m_ud^{msbar}(2 GeV)= 3.85 +- 0.12 +- 0.40 MeV, m_s^{msbar}(2 GeV) = 105 +- 3 +- 9 MeV and m_s/m_ud = 27.3 +- 0.3 +- 1.2. We also obtain fK = 161.7 +- 1.2 +- 3.1 MeV and the ratio fK/fpi=1.227 +- 0.009 +- 0.024. From this ratio, by using the experimental determination of Gamma(K-> mu nu (gamma))/Gamma(pi -> mu nu (gamma)) and the average value of |Vud| from nuclear beta decays, we obtain |Vus|=0.2192(5)(45), in agreement with the determination from Kl3 decays and the unitarity constraint.

Domaines: Physique des Hautes Energies - Réseau [hep-lat]; Physique des Hautes Energies - Phénoménologie [hep-ph]

B. Blossier, Ph. Boucaud, P. Dimopoulos, F. Farchioni, R. Frezzotti, et al.. Light quark masses and pseudoscalar decay constants from Nf=2 Lattice QCD with twisted mass fermions. 2007. ⟨hal-00185775⟩