BK using HYP-smeared staggered fermions in Nf = 2 + 1 unquenched QCD

Journal Article · Mon Dec 20 04:00:00 EST 2010 · Physical Review. D, Particles, Fields, Gravitation and Cosmology

OSTI ID:1025490

Jung, C; Bae, T; Jang, Y-C; Kim, H-J; Kim, J; Kim, K; Lee, W; Sharpe, S; Yoon, B

We present results for the kaon mixing parameter B{sub K} calculated using HYP (hypercubic fat link)-smeared improved staggered fermions on the asqtad lattices generated by the MILC collaboration. We use three lattice spacings (a{approx} 0.12, 0.09 and 0.06 fm), ten different valence-quark masses (m {approx} m{sub s}/10-m{sub s}), and several light sea-quark masses in order to control the continuum and chiral extrapolations. We derive the next-to-leading order staggered chiral perturbation theory (SChPT) results necessary to fit our data, and use these results to do extrapolations based both on SU(2) and SU(3) SChPT. The SU(2) fitting is particularly straightforward because parameters related to taste breaking and matching errors appear only at next-to-next-to-leading order. We match to the continuum renormalization scheme [naive dimensional regularization (NDR)] using one-loop perturbation theory. Our final result is from the SU(2) analysis, with the SU(3) result providing a (less accurate) cross check. We find B{sub K}(NDR, {mu} = 2 GeV) = 0.529 {+-} 0.009 {+-} 0.032 and B{sub K} = B{sub K}(RGI) = 0.724 {+-} 0.012 {+-} 0.043, where the first error is statistical and the second systematic. The error is dominated by the truncation error in the matching factor. Our results are consistent with those obtained using valence domain-wall fermions on lattices generated with asqtad or domain-wall sea quarks.

• Research Organization: BROOKHAVEN NATIONAL LABORATORY (BNL)
• Sponsoring Organization: DOE - OFFICE OF SCIENCE
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 1025490
• Report Number(s): BNL--95407-2011-JA; KA1401020
• Journal Information: Physical Review. D, Particles, Fields, Gravitation and Cosmology, Journal Name: Physical Review. D, Particles, Fields, Gravitation and Cosmology Journal Issue: 11 Vol. 82; ISSN PRVDAQ; ISSN 1550-7998
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BK
CP violation
FATS
FERMIONS
KAONS
PERTURBATION THEORY
QCD
QUANTUM CHROMODYNAMICS
QUARKS
RENORMALIZATION
SEAS
VALENCE
fermions
lattice
unquenched