[Theory-seminars] Theory Seminar, Wednesday Dec 13, 2:00pm, Room F224-225 - Peter Stoffer

[Alessandro Pilloni]

Theory Center Seminar
Wednesday, Dec. 13, 2017
2:00 p.m. (coffee at 1:45 p.m.)
CEBAF Center, Room F224-225

Peter Stoffer (UCSD)

*Dispersion relation for hadronic light-by-light scattering*
**
The anomalous magnetic moment of the muon g-2 has been measured and 
computed to very high precision of about 0.5 ppm. For more than a 
decade, a discrepancy has persisted between experiment and Standard 
Model prediction, now of about 3-4 sigma. The main uncertainty of the 
theory prediction is due to strong interaction effects. With improved 
input for hadronic vacuum polarisation, the subleading hadronic 
light-by-light (HLbL) contribution starts to dominate the theory error. 
While some constraints from QCD exist, the calculation of the HLbL 
contribution to g-2 is plagued by a substantial model dependence. In 
this talk, I will present a dispersive approach to HLbL scattering, 
based on the fundamental principles of unitarity and analyticity. Our 
dispersive formalism recently allowed us to evaluate two-pion 
contributions including rescattering effects and it shows a path towards 
a data-driven determination of the HLbL contribution to g-2 of the muon.



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