Physics – High Energy Physics – High Energy Physics - Lattice
Scientific paper
2011-06-16
Physics Letters B 705 (2011), pp. 477-481
Physics
High Energy Physics
High Energy Physics - Lattice
10 pages, 7 figures. v2: Added one reference and one figure, replaced 2 figures for better readability and updated ensembles,
Scientific paper
10.1016/j.physletb.2011.10.043
Indirect CP violation in K \rightarrow {\pi}{\pi} decays plays a central role in constraining the flavor structure of the Standard Model (SM) and in the search for new physics. For many years the leading uncertainty in the SM prediction of this phenomenon was the one associated with the nonperturbative strong interaction dynamics in this process. Here we present a fully controlled lattice QCD calculation of these effects, which are described by the neutral kaon mixing parameter B_K . We use a two step HEX smeared clover-improved Wilson action, with four lattice spacings from a\approx0.054 fm to a\approx0.093 fm and pion masses at and even below the physical value. Nonperturbative renormalization is performed in the RI-MOM scheme, where we find that operator mixing induced by chiral symmetry breaking is very small. Using fully nonperturbative continuum running, we obtain our main result B_K^{RI}(3.5GeV)=0.531(6)_{stat}(2)_{sys}. A perturbative 2-loop conversion yields B_K^{MSbar-NDR}(2GeV)=0.564(6)_{stat}(3)_{sys}(6)_{PT}, which is in good agreement with current results from fits to experimental data.
Dürr Stephan
Fodor Zoltan
Hoelbling Christian
Katz Sandor D.
Krieg Stefan
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