Photon-pion transition form factor at high photon virtualities within the nonlocal chiral quark modelстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Recently, the BABAR collaboration reported the measurements of the photon–pion transition form factor
Fπγγ*(Q2), which are in strong contradiction to the predictions of the standard factorization approach to per
turbative QCD. In the present work, based on a nonperturbative approach to the QCD vacuum and on rather
universal assumptions, we show that there exist two asymptotic regimes for the pion transition form factor.
One regime with the asymptotic behavior Fπγ*γ(Q2) ~ 1/Q2 corresponds to the result of the standard QCD fac
torization approach, while other violates the standard factorization and leads to asymptotic behavior as
Fπγ*γ(Q2) ~ ln(Q2)/Q2. Furthermore, considering specific nonlocal chiral quark models, we find the region of
parameters, where the existing CELLO, CLEO and BABAR data for the pion transition form factor are suc
cessfully described.