| Issue |
EPJ Web Conf.
Volume 303, 2024
The 16th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon (MENU 2023)
|
|
|---|---|---|
| Article Number | 01007 | |
| Number of page(s) | 6 | |
| Section | Hadron Spectroscopy | |
| DOI | https://doi.org/10.1051/epjconf/202430301007 | |
| Published online | 25 September 2024 | |
https://doi.org/10.1051/epjconf/202430301007
Pion polarizabilities from a dispersive analysis of γγ → ππ
Institut für Kernphysik, Johannes Gutenberg Universität, D-55099 Mainz, Germany
* e-mail: vermolin@uni-mainz.de
Published online: 25 September 2024
We present results for the charged and neutral pion polarizabilities, obtained through a dispersive analysis of photon-fusion reactions with two pions in the final state. This analysis is motivated by current and future measurements at COMPASS, JLab (Hall D), and the BESIII measurement of singlevirtual photon-fusion reactions in the space-like region, offering insight into generalized pion polarizabilities. To improve upon predictions within an un-subtracted dispersion formalism with only the pion left-hand cut, one needs to consider the influence of heavier left-hand cuts. We parametrize the latter using an expansion in a suitably constructed conformal variable, capturing the analytical structure of the left-hand cuts. The coefficients in this expansion are determined from the matching with the Lagrangian-based approach, the Adler zero constraint for γγ → π0π0, and a fit to the cross-section data. The extension to the single-virtual case is also discussed.
© The Authors, published by EDP Sciences, 2024
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