Lattice QCD Inputs to the CKM Unitarity Triangle Analysis

By J. Laiho, R. V. D. Water, E. Lunghi. 2009

206 citations recorded by the source corpus.

We perform a global fit to the Cabibbo-Kobayashi-Maskawa unitarity triangle using the latest experimental and theoretical constraints. Our emphasis is on the hadronic weak matrix elements that enter the analysis, which must be computed using lattice QCD or other nonperturbative methods. Realistic lattice QCD calculations which include the effects of the dynamical up, down, and strange quarks are now available for all of the standard inputs to the global fit. We therefore present lattice averages for all of the necessary hadronic weak matrix elements. We attempt to account for correlations between lattice QCD results in a reasonable but conservative manner: whenever there are reasons to believe that an error is correlated between two lattice calculations, we take the degree of correlation to be 100%. These averages are suitable for use as inputs both in the global Cabibbo-Kobayashi-Maskawa unitarity triangle fit and other phenomenological analyses. In order to illustrate the impact of the lattice averages, we make standard model predictions for the parameters B-circumflex{sub K}, |V{sub cb}|, and |V{sub ub}|/|V{sub cb}|. We find a (2-3){sigma} tension in the unitarity triangle, depending upon whether we use the inclusive or exclusive determination of |V{sub cb}|. If we interpret the tension as a signmore » of new physics in either neutral kaon or B mixing, we find that the scenario with new physics in kaon mixing is preferred by present data.« less

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Citations in the corpus

Probing Novel Scalar and Tensor Interactions from (Ultra)Cold Neutrons to the LHC (2011, methodology): “It has been successfully employed to calculate hadron masses and their decay properties, such as matrix elements, with control over statistical and all systematic errors, in many cases at higher precision than can be measured experimentally [66, 67].”
Epsilon_K at Next-to-Next-to-Leading Order: The Charm-Top-Quark Contribution (2010, background): “is a renormalisation-group invariant quantity, which can be calculated on the lattice with high precision – see for instance [9].”
Model-independent constraints on new physics in b → s transitions (2011, background): “Since LCSR only give predictions for the B meson decay constant times a form factor, we add an additional relative uncertainty of twice the uncertainty of fB = (205 ± 12) MeV [21] to the branching ratio.”