Pion polarizabilities from a dispersive analysis of $\gamma\gamma \to \pi\pi$
| Autor: | Ermolina, Viktoriia, Danilkin, Igor, Vanderhaeghen, Marc |
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| Rok vydání: | 2024 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | 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 single-virtual photon-fusion reactions in the space-like region, offering insight into generalized pion polarizabilities. To improve predictions within an unsubtracted 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 $\gamma\gamma \to \pi^0\pi^0$, and a fit to the cross-section data. The extension to the single-virtual case is also discussed. Comment: 6 pages, 1 figure. Proceedings contribution to MENU2023 conference |
| Databáze: | arXiv |
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