Abstract
As part of the UKQCD and RBC collaborations' N_f=2+1 domain-wall fermion phenomenology programme, we calculate the first two moments of the light-cone distribution amplitudes of the pseudoscalar mesons pion and kaon and the (longitudinally-polarised) vector mesons rho, K-star and phi. We obtain the desired quantities with good precision and are able to discern the expected quark-mass dependence of SU(3)-flavour breaking effects. An important ingredient of the calculation is the nonperturbative renormalisation of lattice operators using the RI'/MOM technique.
Highlights
Light-cone distribution amplitudes (DAs) are important nonperturbative quantities which parameterise in partonic terms the components of the hadronic wavefunction that control hard exclusive processes
The result for ξ1 K in Table XI supercedes but is compatible with our earlier result in [41, 42], which was obtained on the 163 × 32 ensembles only and used perturbative renormalisation
Converting the lowest moment of the kaon distribution amplitude to the first Gegenbauer moment a1K = 0.061(2)(4), we find it in agreement with sum rule results from Eq (16) but with a much reduced uncertainty
Summary
Light-cone distribution amplitudes (DAs) are important nonperturbative quantities which (within the framework of collinear factorisation) parameterise in partonic terms the components of the hadronic wavefunction that control hard exclusive processes. Such processes provide hadron structure information complementary to that obtained from hard inclusive reactions. Hard exclusive processes are controlled at leading-order by the distribution amplitudes of leadingtwist (an operator’s twist is the difference between its dimension and its spin): essentially the overlap of the hadronic state with the valence Fock state in which, for a meson, the collinear quark-antiquark pair have small transverse separation and carry longitudinal momentum fractions u and u = 1 − u. The vector meson decay constant, fρ, and its coupling to the tensor current, fρT , are of interest in their own right and we have for V ∈ {ρ, previously K∗, φ} as calculated [13] the ratios part of our domain-wall fVT /fV , fermion (DWF) phenomenology programme
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