scholarly journals Chiral anomaly transition form factor of γ → 3π in nonlocal quark model

2019 ◽  
Vol 204 ◽  
pp. 02001
Author(s):  
Alexey Zhevlakov
Keyword(s):  
Form Factor ◽  
Quark Model ◽  
Transition Form Factor ◽  
Local Limit ◽  
Gamma Transition ◽  
Chiral Anomaly ◽  
Chiral Quark Model ◽  
Transition Form

Chiral anomaly of gamma transition into three pions are studied in a framework of nonlocal chiral quark model. In the local limit the result is in agreement with chiral perturbative theory and reproducesWess-Zumino-Witten anomaly. Transition form factor of gamma into three pions in nonlocal quark model has a correction which vanishes in local limit.

THE ANOMALOUS PROCESS γπ → ππ AND ITS IMPACT ON THE π0 TRANSITION FORM FACTOR

2014 ◽  
Vol 35 ◽  
pp. 1460397
Author(s):  
BASTIAN KUBIS
Keyword(s):  
Form Factor ◽  
Phase Shift ◽  
Theoretical Analysis ◽  
Cross Section ◽  
Transition Form Factor ◽  
P Wave ◽  
Chiral Anomaly ◽  
Transition Form ◽  
Dispersive Representation ◽  
Important Input

The process γπ → ππ, in the limit of vanishing photon and pion energies, is determined by the chiral anomaly. This reaction can be investigated experimentally using Primakoff reactions, as currently done at COMPASS. We derive a dispersive representation that allows one to extract the chiral anomaly from cross-section measurements up to 1 GeV, where effects of the ρ resonance are included model-independently via the ππ P-wave phase shift. We discuss how this amplitude serves as an important input to a dispersion-theoretical analysis of the π0 transition form factor, which in turn is a vital ingredient to the hadronic light-by-light contribution to the anomalous magnetic moment of the muon.

scholarly journals CHIRAL ANOMALY EFFECTS AND THE BABAR MEASUREMENTS OF THE γγ* → π0 TRANSITION FORM-FACTOR

2011 ◽  
Vol 26 (23) ◽  
pp. 4125-4131 ◽  
Author(s):  
T. N. PHAM ◽  
X. Y. PHAM
Keyword(s):  
Form Factor ◽  
Perturbative Qcd ◽  
Virtual Photon ◽  
Transition Form Factor ◽  
High Energy ◽  
Chiral Anomaly ◽  
Steady Increase ◽  
Transition Form ◽  
Babar Data ◽  
Energy Processes

The recent BaBar measurements of the γγ*→π0 transition form-factor show spectacular deviation from perturbative QCD prediction for large spacelike Q2 up to 34 GeV2. When plotted against Q2, Q2F(Q2) shows steady increase with Q2 in contrast with the flat Q2 behavior predicted by perturbative QCD, and at 34 GeV2 is more than 50% larger than the QCD prediction. Stimulated by the BaBar measurements, we revisit our previous paper on the cancellation of anomaly effects in high energy processes Z0→π0γ, e+e- → π0γ and apply our results to the γ*γ→π0 transition form-factor measured in the e+e- → e+e-π0 process with one highly virtual photon. We find that, the transition form-factor F(Q2) behaves as [Formula: see text] and produces a striking agreement with the BaBar data for Q2F(Q2) with m = 132 MeV which also reproduces very well the CLEO data at lower Q2.

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