DOI: 10.1140/epjc/s2002-01042-1
Exploring light-cone sum rules for pion and kaon form factors
J. Bijnens1 and A. Khodjamirian21 Department of Theoretical Physics, Lund University, Sölvegatan 14A, 223 62 Lund, Sweden
2 Institut für Theoretische Teilchenphysik, Universität Karlsruhe, 76128 Karlsruhe, Germany
(Received: 30 June 2002 / Published online: 7 October 2002 )
Abstract
We analyze the higher-twist effects and the
SU(3)-flavor symmetry
breaking
in the correlation functions used to calculate form factors of
pseudoscalar mesons in the QCD light-cone sum rule approach.
It is shown that the Ward identities for these correlation functions
yield
relations between twist-4 two- and three-particle distribution
amplitudes. In addition to the
relations already obtained from the QCD equations of motions,
we have found a new one. With the help of these relations, the
twist-4 contribution to the light-cone sum rule
for the pion electromagnetic form factor is reduced to a very
simple
form. Simultaneously, we correct a sign error in an earlier
calculation.
The updated light-cone sum rule prediction for the pion
form factor at intermediate
momentum transfers is compared with the recent Jefferson Lab
data.
Furthermore, from the correlation functions with strange-quark
currents
the kaon electromagnetic form factor and the
weak
transition
form factors are predicted with
accuracy.
© Società Italiana di Fisica, Springer-Verlag 2002
