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Electromagnetic pion and kaon form factors in light-cone resummed perturbative QCD Udit Raha* and Andreas Aste
 

Summary: Electromagnetic pion and kaon form factors in light-cone resummed perturbative QCD
Udit Raha* and Andreas Aste
Department of Physics, University of Basel, Switzerland
(Received 11 December 2008; published 18 February 2009)
We analyze the electromagnetic pion and kaon form factor by including radiative and higher-twist
effects within the framework of resummed perturbative QCD in the spacelike region. We focus on the
transition from the perturbative to nonperturbative behavior in the phenomenological intermediate-energy
regime. Using a modified ``kT'' factorization scheme with transverse degrees of freedom, we evaluate the
nonperturbative soft contributions as distinct from the hard contributions, ensuring no double counting via
the Ward identity at Q2 ¼ 0. The soft contributions are obtained via local quark-hadron duality, while the
hard contributions rest on the well-known collinear factorization theorem using model wave functions
with modified Brodsky-Huang-Lepage­type ansatz and distribution amplitudes derived from light-cone
QCD sum rules. Our analysis shows that the perturbative hard part prevails for large Q2
beyond
50­100 GeV2
, while for low and moderate momentum transfers below 10­16 GeV2
, the soft contribu-
tions dominate over the hard part. Thus, we demonstrate the importance of including the soft contributions
for explaining the experimental form-factor data.
DOI: 10.1103/PhysRevD.79.034015 PACS numbers: 12.38.Bx, 12.38.Cy, 12.39.St, 13.40.Gp

  

Source: Aste, Andreas - Institut für Physik, Universität Basel

 

Collections: Physics