出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We report on recent progress in the calculation of BK using HYP-smeared staggered fermions on the MILC asqtad lattices. Our main focus is on the continuum extrapolation, which is done using (up to) four different lattice spacings—a 0.12, 0.09, 0.06 and 0.045 fm. Since Lattice 2010, we have reduced the statistical errors on the a 0:09 fm lattices by a factor of 3, and roughly doubled the size of the a 0:045 fm ensemble. We find that these improvements have a very significant impact on the continuum extrapolation, with the a 0:12 fm data lying outside the range of applicability of simple functional forms. Hence we use only the three smallest lattice spacings to perform the extrapolation, finding ˆBK =BK(RGI)=0:7250:004(stat)0:038(sys). This value is consistent with our published value from 2010 (based the three coarsest lattice spacings), but has smaller errors.
