Higher-twist corrections to $D\to\pi,K$ form factors from light-cone sum rules

TL;DR

This paper computes $D o ext{pion, kaon}$ form factors using light-cone sum rules, emphasizing higher-twist corrections and SU(3) breaking effects, leading to improved understanding of CKM matrix elements.

Contribution

It introduces the calculation of higher-twist corrections to $D o P$ form factors within LCSR, including SU(3) breaking effects, and provides updated CKM matrix element estimates.

Findings

Higher-twist contributions are significant for form factors.

SU(3) breaking effects are quantified and confirmed.

Predicted CKM elements have sizable uncertainties.

Abstract

We calculate the $D\to P$ transition form factors within the framework of the light-cone QCD sum rules (LCSR) with the $D$-meson light-cone distribution amplitudes (LCDAs). The next-to-leading power (NLP) corrections to the vacuum-to-$D$-meson correlation function are considered, and the NLP corrections from the high-twist $D$-meson LCDAs and the SU(3) breaking effect from strange quark mass are investigated. Adopting the exponential model of the $D$-meson LCDAs,the predicted SU(3) flavor symmetry breaking effects are $R_{SU(3)}^{+,0}=1.12$ and $R_{SU(3)}^{T}=1.39$, respectively, which confirms the results from LCSR with pion LCDA. The numerical predictions of the form factors show that the contribution from two-particle higher-twist contributions is of great importance and the uncertainties are dominated by the inverse moment of $\phi_D^+(\omega, \mu)$. With the obtained form factors, the predicted Cabibbo-Kobayashi-Maskawa (CKM) matrix elements are $|V_{cd}|=0.151\,{}^{+0.091}_{-0.043} \big |_{\rm th.}\,{}^{+0.017}_{-0.02} \big |_{\rm exp.}$ and $|V_{cs}|=0.89\,{}^{+0.467}_{-0.234} \big |_{\rm th.}\,{}^{+0.008}_{-0.008} \big |_{\rm exp.}$.