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arXiv · 1505.06639

ΔS=2 and ΔC=2 bag parameters in the SM and beyond from Nf=2+1+1 twisted-mass LQCD

N. Carrasco·P. Dimopoulos·R. Frezzotti·V. Lubicz·G. C Rossi·S. Simula·C. Tarantino
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Abstract

We present unquenched lattice QCD results for the matrix elements of four-fermion operators relevant to the description of the neutral K and D mixing in the Standard Model and its extensions. We have employed simulations with Nf = 2 + 1 + 1 dynamical sea quarks at three values of the lattice spacings in the interval 0.06 - 0.09 fm and pseudoscalar meson masses in the range 210 - 450 MeV. Our results are extrapolated to the continuum limit and to the physical pion mass. Renormalization constants have been determined non-perturbatively in the RI-MOM scheme. In particular, for the Kaon bag-parameter, which is relevant for the \overline{K}^0-K^0 mixing in the Standard Model, we obtain B_K^{RGI} = 0.717(24).

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N. Carrasco, P. Dimopoulos, R. Frezzotti, V. Lubicz, G. C Rossi, S. Simula, C. Tarantino. 2015-08-07. ΔS=2 and ΔC=2 bag parameters in the SM and beyond from Nf=2+1+1 twisted-mass LQCD. https://doi.org/10.1103/physrevd.92.034516

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