Abstract
We present the first lattice-QCD calculation of the kaon distribution amplitude using the large-momentum effective theory (LaMET) approach. The momentum-smearing technique has been implemented to improve signals at large meson momenta. We subtract the power divergence due to Wilson line to high precision using multiple lattice spacings. The kaon structure clearly shows an asymmetry of the distribution amplitude around x=1/2, a clear sign of its skewness. Our result also prefers a broader distribution than the asymptotic form. We also study the leading SU(3) flavor symmetry breaking relations for the pion, kaon and eta meson distribution amplitudes, and the results are consistent with the prediction from chiral perturbation theory.
Highlights
Meson distribution amplitudes (DAs) φM are important universal quantities appearing in many factorization theorems which allow for the description of exclusive processes at large momentum transfers Q2
We have presented the first lattice calculation of the kaon distribution amplitude using the large-momentum effective theory (LaMET) approach with a pion mass of 310 MeV
We subtract the power divergence due to Wilson line using the counterterm δm determined to 2% accuracy using multiple lattice spacings—a significant improvement over our previous pion-DA work
Summary
Meson distribution amplitudes (DAs) φM are important universal quantities appearing in many factorization theorems which allow for the description of exclusive processes at large momentum transfers Q2. It will be interesting to investigate whether the above leading SU(3) breaking relations derived from ChPT emerge from direct computations of meson DAs in lattice QCD Such direct computations have become possible recently, thanks to the large-momentum effective theory (LaMET) [8,9,10]. It was suggested that one can study instead an Ioffe-time or pseudo distribution [36] which is related to the quasi-distribution through a simple Fourier transform While this method shows some interesting renormalization features [37], it is essentially equivalent to the LaMET approach [10,38,39] and offers no new physics regarding the factorization into PDFs. In addition, there are proposals using currentcurrent correlators to compute PDFs, the pion DA, etc.
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