Hadronic light-by-light scattering in the muon g-2: A new short-distance constraint on pion exchange
- Regional Centre for Accelerator-based Particle Physics, Harish-Chandra Research Institute, Chhatnag Road, Jhusi, Allahabad - 211 019 (India)
Recently it was pointed out that for the evaluation of the numerically dominant pion-exchange contribution to the hadronic light-by-light scattering correction in the muon g-2, a fully off-shell pion-photon-photon form factor should be used. Following this proposal, we first derive a new short-distance constraint on the off-shell form factor which enters at the external vertex for the muon g-2 and show that it is related to the quark condensate magnetic susceptibility in QCD. We then evaluate the pion-exchange contribution in the framework of large-N{sub C} QCD using an off-shell form factor which fulfills all short-distance constraints. With a value for the magnetic susceptibility as estimated in the same large-N{sub C} framework, we obtain the result a{sub {mu}}{sup LbyL;{pi}{sup 0}}=(72{+-}12)x10{sup -11}. Updating our earlier results for the contributions from the exchanges of the {eta} and {eta}{sup '} using simple vector-meson dominance form factors, we obtain a{sub {mu}}{sup LbyL;PS}=(99{+-}16)x10{sup -11} for the sum of all light pseudoscalars. Combined with available evaluations for the other contributions to hadronic light-by-light scattering this leads to the new estimate a{sub {mu}}{sup LbyL;had}=(116{+-}40)x10{sup -11}.
- OSTI ID:
- 21308153
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 79, Issue 7; Other Information: DOI: 10.1103/PhysRevD.79.073012; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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