$K$ and $D$ oscillations in the Standard Model and its extensions from $N_f=2+1+1$ Twisted Mass LQCD

TL;DR

This paper reports the first $N_f=2+1+1$ lattice QCD calculations of matrix elements relevant for $K$ and $D$ meson mixing, using improved techniques to ensure accurate continuum and physical mass extrapolations.

Contribution

It provides novel $N_f=2+1+1$ results for neutral meson mixing matrix elements with non-perturbative renormalization and improved lattice methods.

Findings

Results extrapolated to continuum and physical quark masses.

Non-perturbative renormalization constants computed in RI-MOM scheme.

Simulations include three lattice spacings and a range of meson masses.

Abstract

We present the first $N_f=2+1+1$ results for the matrix elements of the operators describing neutral $K$ and $D$ mixing in the Standard Model and its extensions. The combination of maximally twisted sea quarks and Osterwalder-Seiler valence quarks ensures $\mathcal{O}(a)$-improvement and continuum like renormalization pattern. We have used the $N_f=2+1+1$ dynamical quark gauge configurations generated by ETMC. Simulations include three lattice spacings in the interval $[0.06:0.09]$ fm and pseudoscalar meson masses in the range $[230:500]$ MeV. Our results are extrapolated to the continuum limit and to the physical quark masses. The calculation of the renormalization constants has been performed non-perturbatively in the RI-MOM scheme.