We present an unquenched N(f) = 2 lattice computation of the B(K) parameter which controls K(0) - (K) over bar (0) oscillations. A partially quenched setup is employed with two maximally twisted dynamical (sea) light Wilson quarks, and valence quarks of both the maximally twisted and the Osterwalder-Seiler variety. Suitable combinations of these two kinds of valence quarks lead to a lattice definition of the B(K) parameter which is both multiplicatively renormalizable and O(a) improved. Employing the nonperturbative RI-MOM scheme, in the continuum limit and at the physical value of the pion mass we get B(K)(RGI) = 0.729 +/- 0.030, a number well in line with the existing quenched and unquenched determinations.
Constantinou, M., Dimopoulos, P., Frezzotti, R., Jansen, K., Gimenez, V., Lubicz, V., et al. (2011). BK-parameter from Nf=2 twisted mass lattice QCD. PHYSICAL REVIEW D, PARTICLES, FIELDS, GRAVITATION, AND COSMOLOGY, 83(1) [10.1103/PhysRevD.83.014505].
BK-parameter from Nf=2 twisted mass lattice QCD
LUBICZ, Vittorio;
2011-01-01
Abstract
We present an unquenched N(f) = 2 lattice computation of the B(K) parameter which controls K(0) - (K) over bar (0) oscillations. A partially quenched setup is employed with two maximally twisted dynamical (sea) light Wilson quarks, and valence quarks of both the maximally twisted and the Osterwalder-Seiler variety. Suitable combinations of these two kinds of valence quarks lead to a lattice definition of the B(K) parameter which is both multiplicatively renormalizable and O(a) improved. Employing the nonperturbative RI-MOM scheme, in the continuum limit and at the physical value of the pion mass we get B(K)(RGI) = 0.729 +/- 0.030, a number well in line with the existing quenched and unquenched determinations.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
