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arXiv · 1410.7159

Kaon semileptonic vector form factor with $N_f=2+1+1$ Twisted Mass fermions

Nuria Carrasco·Paolo Lami·Vittorio Lubicz·Eleonora Picca·Lorenzo Riggio·Silvano Simula·Cecilia Tarantino
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Abstract

We investigate the vector form factor relevant for the $K_{\ell 3}$ semileptonic decay using maximally twisted-mass fermions with 4 dynamical flavours ($N_f=2+1+1$). Our simulations feature pion masses ranging from $210$ MeV to approximately $450$ MeV and lattice spacing values as small as $0.06$fm. Our main result for the vector form factor at zero 4-momentum transfer is $f_+(0)=0.9683(65)$ where the uncertainty is both statistical and systematic. By combining our result with the experimental value of $f_+(0)|V_{us}|$ we obtain $|V_{us}|=0.2234(16)$, which satisfies the unitarity constraint of the Standard Model at the permille level.

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Nuria Carrasco, Paolo Lami, Vittorio Lubicz, Eleonora Picca, Lorenzo Riggio, Silvano Simula, Cecilia Tarantino. 2014-10-27. Kaon semileptonic vector form factor with $N_f=2+1+1$ Twisted Mass fermions. https://arxiv.org/abs/1410.7159

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