version française rss feed
HAL : in2p3-00639340, version 1

Fiche détaillée  Récupérer au format
29th International Symposium on Lattice Field Theory (Lattice 2011), Squaw Valley : États-Unis (2011)
K^0-\bar{K}^0 mixing in the Standard Model from Nf=2+1+1 Twisted Mass Lattice QCD
N. Carrasco, V. Gimenez, P. Dimopoulos, R. Frezzotti, D. Palao, G. C. Rossi, V. Lubicz, M. Papinutto1, F. Sanfilippo, S. Simula

We present preliminary results at {\beta} = 1.95 (a = 0.077 fm) on the first unquenched N_f=2+1+1 lattice computation of the B_K parameter which controls the neutral kaon oscillations in the Standard Model. Using N_f=2+1+1 maximally twisted sea quarks and Osterwalder-Seiler valence quarks we achieve O(a) improvement and a continuum-like renormalization pattern for the four-fermion operator. Our results are extrapolated/interpolated to the physical light/strange quark mass but not yet to the continuum limit. The computation of the relevant renormalization constants is performed non perturbatively in the RI'-MOM scheme using dedicated simulations with N_f=4 degenerate sea quark flavours produced by the ETM collaboration. We get B_K^{RGI} (a = 0.077) = 0.747(18), which when compared to our previous unquenched N_f=2 determination and most of the existing results, suggests a rather weak B_K^{RGI} dependence on the number of dynamical flavours. We are at the moment analysing lattice data at two additional {\beta} values which will allow us to perform an extrapolation to the continuum limit.
1 :  LPSC - Laboratoire de Physique Subatomique et de Cosmologie
Physique/Physique des Hautes Energies - Réseau
Lien vers le texte intégral :