Pion polarizabilities from a γ γ →π π analysis
Abstract
We present results for pion polarizabilities predicted using dispersion relations from our earlier amplitude analysis of world data on two photon production of meson pairs. The helicity-zero polarizabilities are rather stable and insensitive to uncertainties in cross-channel exchanges. The need is first to confirm the recent result on (α1-β1) for the charged pion by COMPASS at CERN to an accuracy of 10% by measuring the γ γ →π+π- cross section to an uncertainty of 1%. Then the same polarizability, but for π0, is fixed to be (α1-β1)π0=(0.9 ±0.2 )×10-4 fm3 . By analyzing the correlation between uncertainties in the meson polarizability and those in γ γ cross sections, we suggest experiments need to measure these cross sections between √{s }≃350 and 600 MeV. The π0π0 cross section then makes the (α2-β2)π0 the easiest helicity-two polarizability to determine.
- Publication:
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Physical Review D
- Pub Date:
- December 2016
- DOI:
- 10.1103/PhysRevD.94.116021
- arXiv:
- arXiv:1611.04441
- Bibcode:
- 2016PhRvD..94k6021D
- Keywords:
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- High Energy Physics - Phenomenology
- E-Print:
- 18 pages, 4 figures, a few typos corrected