$D$-meson semileptonic form factors at zero momentum transfer in (2+1+1)-flavor lattice QCD

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We present a calculation of the $D\to K \ell \nu$ and $D\to\pi \ell \nu$ semileptonic form factors at $q^2=0$, which enable determinations of the CKM matrix elements $\lvert{V_{cs}}\rvert$ and $\lvert{V_{cd}}\rvert$, respectively.

• We use gauge-field configurations generated by the MILC collaboration with four flavors of highly-improved staggered (HISQ) quarks, analyzing several ensembles including those with physical pion masses and approximate lattice spacings ranging from 0.12~fm to 0.042~fm.
• We also use the HISQ action for the valence quarks.
• We employ twisted boundary conditions to calculate the form factors at zero momentum transfer directly.