Eur. Phys. J. C (2015) 75: 45
https://doi.org/10.1140/epjc/s10052-015-3271-6

Regular Article - Theoretical Physics

Heavy pseudoscalar leading-twist distribution amplitudes within QCD theory in background fields

¹ Institute of High Energy Physics and Theoretical Physics Center for Science Facilities, Chinese Academy of Sciences, Beijing, 100049, People’s Republic of China
² Department of Physics, Chongqing University, Chongqing, 401331, People’s Republic of China

^* e-mail: zhongtao@ihep.ac.cn

Received: 30 September 2014
Accepted: 11 January 2015
Published online: 3 February 2015

Abstract

In this paper, we study the leading-twist distribution amplitude (DA) of the heavy pseudoscalars (HPs), such as , , and , within the QCD theory in the background fields. New sum rules up to dimension-six condensates for both the HP decay constants and their leading-twist DA moments are presented. From the sum rules for the HP decay constants, we obtain , , and . Based on the sum rules for the HPs’ leading-twist DA moments, we construct a new model for the , , and leading-twist DAs. Our present HP DA model is also adaptable for the light pseudoscalar DAs, such as the pion and kaon DAs. Thus, it shall be applicable for a wide range of QCD exclusive processes. As an application, we apply the leading-twist DA to calculate the transition form factor . At the maximum recoil region, we obtain . Furthermore we predict the branching ratio for the semi-leptonic decay and obtain for massless leptons, which is consistent with the light-cone sum rules estimation obtained in the literature.