Photon-pion Transition Form Factor and Pion Distribution Amplitude
The pion distribution amplitude (DA) ??(x) [1,2] is an important function accumulating information about momentum sharing between the quarks of the pion when the latter is in its valence q¯q configuration. It is an inherent element of perturbative QCD calculations of hard exclusive reactions involving the pion. A scenario is investigated in which the leading-twist pion DA ??(x) is approximated by the pion decay constant f? for all essential values of the light-cone fraction x. A model for the light-front wave function ?(x,k?) is proposed that produces such a DA and has a rapidly decreasing (exponential for definiteness) dependence on the light-front energy combination k2?/x(1?x). It is shown that this model easily reproduces the fit of recent large-Q2 {\sc BaBar} data [3] on the photon-pion transition form factor. Some aspects of scenario with flat pion distribution amplitude are discussed. \\[4pt] [1]~A.~V.~Radyushkin, JINR-P2-10717 (1977); English translation: arXiv:hep-ph/0410276.\\[0pt] [2] G.~P.~Lepage and S.~J.~Brodsky, Phys.\ Lett.\ B {\bf 87}, 359 (1979).\\[0pt] [3] B.~Aubert {\it et al.} [{\sc BaBar} Collaboration], arXiv:0905.4778 [hep-ex].
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP)
- DOE Contract Number:
- AC05-06OR23177
- OSTI ID:
- 2001474
- Report Number(s):
- JLAB-THY-09-1141; DOE/OR/23177-7158
- Resource Relation:
- Conference: 3rd Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan, October 13–17, 2009; Waikoloa, Hawaii
- Country of Publication:
- United States
- Language:
- English
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