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arXiv · 1309.2040

Neutral kaon mixing from new physics: matrix elements in $N_f=2+1$ QCD

Taegil Bae·Yong-Chull Jang·Hwancheol Jeong·Chulwoo Jung·Hyung-Jin Kim·Jangho Kim·Jongjeong Kim·Kwangwoo Kim·Sunghee Kim·Weonjong Lee·Jaehoon Leem·Stephen R. Sharpe·Boram Yoon·SWME Collaboration
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Abstract

We present results for matrix elements of $ΔS=2$ four-fermion operators arising generically in models of new physics. These are needed to constrain such models using the measured values of $\varepsilon_K$ and $ΔM_K$. We use lattice QCD with 2+1 flavors of improved staggered fermions on lattices generated by the MILC collaboration. We extrapolate to the continuum from three lattice spacings ranging down to $a\approx 0.045\;$fm. Total errors are $\sim 5-6%$, arising primarily from our use of one-loop matching between lattice and continuum operators. For two of the matrix elements, our results disagree significantly from those obtained using different fermion discretizations.

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Taegil Bae, Yong-Chull Jang, Hwancheol Jeong, Chulwoo Jung, Hyung-Jin Kim, Jangho Kim, Jongjeong Kim, Kwangwoo Kim, Sunghee Kim, Weonjong Lee, Jaehoon Leem, Stephen R. Sharpe, Boram Yoon, SWME Collaboration. 2013-10-05. Neutral kaon mixing from new physics: matrix elements in $N_f=2+1$ QCD. https://doi.org/10.1103/physrevd.88.071503

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