The asymptotics of the transition form factor {gamma}{gamma}{sup *} {r_arrow} {pi}{sup 0}
Conference
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OSTI ID:756324
In this paper the authors present the result of a direct QCD sum rule calculation of the transition form factor {gamma}{gamma}{sup *} {r_arrow} {pi}{sup 0} in the region of moderately large invariant momentum Q{sup 2} > 1GeV{sup 2} of the virtual photon. In contrast to pQCD, they make no assumptions about the shape of the pion distribution amplitude {var_phi}{sub {pi}}(x). Their results agree with the Brodsky-Lepage proposal that the Q{sup 2}-dependence of this form factor is given by an interpolation between its Q{sup 2}=0 value fixed by the axial anomaly and 1/Q{sup 2} pQCD behavior for large Q{sup 2}, with normalization corresponding to the asymptotic form {var_phi}{sub pi}{sup as}(x)=6 f{sub {pi}}x(1{minus}x) of the pion distribution amplitude. Their prediction for the from factor F{sub {gamma}}{sup *}{gamma}{sup *}{pi}{sup 0}(q{sub 1}{sup 2} = 0,q{sub 2}{sup 2} = {minus}Q{sup 2}) is in good agreement with new CLEO data.
- Research Organization:
- Thomas Jefferson National Accelerator Facility, Newport News, VA (US)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC05-84ER40150
- OSTI ID:
- 756324
- Report Number(s):
- DOE/ER/40150-1559; JLAB-THY-97-24; hep-ph/9706518
- Country of Publication:
- United States
- Language:
- English
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