Unquenched determination of the kaon parameter B_K from improved staggered fermions

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dc.creatorGamiz, E.
dc.creatorCollins, S.
dc.creatorDavies, C. T. H.
dc.creatorLepage, G. P.
dc.creatorShigemitsu, J.
dc.creatorWingate, M.
dc.date2006-03-27
dc.date.accessioned2026-07-07T10:28:44Z
dc.date.available2026-07-07T10:28:44Z
dc.descriptionThe use of improved staggered actions (HYP, Asqtad) has been proved to reduce the scaling corrections that affected previous calculations of B_K with unimproved (standard) staggered fermions in the quenched approximation. This improved behaviour allows us to perform a reliable calculation of B_K including quark vacuum polarization effects, using the MILC configurations with n_f=2+1 flavours of sea fermions. We perform such a calculation for a single lattice spacing, a=0.125 fm, and with kaons made up of degenerate quarks with m_s/2. The valence strange quark mass m_s is fixed to its physical value and we use two different values of the light sea quark masses. After a chiral extrapolation of the results to the physical value of the sea quark masses, we find \hat B_K = 0.83+-0.18, where the error is dominated by the uncertainty in the lattice to continuum matching at O(α_s^2). The matching will need to be improved to get the precision needed to make full use of the experimental data on ε_K to constrain the unitarity triangle.
dc.description15 pages, 6 figures
dc.identifierhttps://arxiv.org/abs/hep-lat/0603023
dc.identifierhttp://arxiv.org/abs/hep-lat/0603023
dc.identifierPhys.Rev.D73:114502,2006
dc.identifierdoi:10.1103/PhysRevD.73.114502
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/177551
dc.subjectHigh Energy Physics - Lattice
dc.subjectHigh Energy Physics - Phenomenology
dc.titleUnquenched determination of the kaon parameter B_K from improved staggered fermions
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