Pion polarizabilities from a dispersive analysis of $γγ\to ππ$
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| Auteurs principaux: | , , |
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| Format: | Preprint |
| Publié: |
2024
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| _version_ | 1866913454031372288 |
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| author | Ermolina, Viktoriia Danilkin, Igor Vanderhaeghen, Marc |
| author_facet | Ermolina, Viktoriia Danilkin, Igor Vanderhaeghen, Marc |
| contents | 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 $γγ\to π^0π^0$, and a fit to the cross-section data. The extension to the single-virtual case is also discussed. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2407_21471 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Pion polarizabilities from a dispersive analysis of $γγ\to ππ$ Ermolina, Viktoriia Danilkin, Igor Vanderhaeghen, Marc High Energy Physics - Phenomenology 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 $γγ\to π^0π^0$, and a fit to the cross-section data. The extension to the single-virtual case is also discussed. |
| title | Pion polarizabilities from a dispersive analysis of $γγ\to ππ$ |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2407.21471 |