Pion pair production in e + e − annihilation at next-to-leading order matched to Parton Shower
Abstract The pion pair production in e + e − annihilation at flavour factories plays a crucial role in the determination of the hadronic contribution to the muon anomalous magnetic moment. The recent CMD-3 measurement of the pion form factor via energy scan displays a significant difference with the...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2025-05-01
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| Series: | Journal of High Energy Physics |
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| Online Access: | https://doi.org/10.1007/JHEP05(2025)196 |
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| author | Ettore Budassi Carlo M. Carloni Calame Marco Ghilardi Andrea Gurgone Guido Montagna Mauro Moretti Oreste Nicrosini Fulvio Piccinini Francesco P. Ucci |
| author_facet | Ettore Budassi Carlo M. Carloni Calame Marco Ghilardi Andrea Gurgone Guido Montagna Mauro Moretti Oreste Nicrosini Fulvio Piccinini Francesco P. Ucci |
| author_sort | Ettore Budassi |
| collection | DOAJ |
| description | Abstract The pion pair production in e + e − annihilation at flavour factories plays a crucial role in the determination of the hadronic contribution to the muon anomalous magnetic moment. The recent CMD-3 measurement of the pion form factor via energy scan displays a significant difference with the previous experimental determinations. In order to contribute to an improved theoretical description and simulation of energy scan experiments, we present a calculation of the e + e − → π + π −(γ) hadronic channel at next-to-leading order matched to a Parton Shower algorithm in QED and sQED. According to the recent advances in the literature, particular attention is paid to the treatment of the pion composite structure in loop diagrams beyond the commonly used factorised sQED approach, as well as to the modelling of multiple photon radiation through the Parton Shower algorithm. In particular, we carry out a detailed discussion on the inclusion of the pion form factor in the virtual sQED corrections according to two independent methods, inspired by the generalised vector meson dominance model and the dispersive approach, respectively. We find the two methods to be in remarkable agreement. We show phenomenological results for inclusive and differential observables which are relevant for precision energy scan measurements, focusing on the impact of the radiative corrections and the effect of the various approaches for the treatment of the pion form factor. Our calculation is implemented in an updated version of the Monte Carlo event generator BabaYaga@NLO, that can be used for fully exclusive simulations in data analysis. |
| format | Article |
| id | doaj-art-eab3ea39de3442ccadef7fa62124febd |
| institution | DOAJ |
| issn | 1029-8479 |
| language | English |
| publishDate | 2025-05-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj-art-eab3ea39de3442ccadef7fa62124febd2025-08-20T03:10:27ZengSpringerOpenJournal of High Energy Physics1029-84792025-05-012025515110.1007/JHEP05(2025)196Pion pair production in e + e − annihilation at next-to-leading order matched to Parton ShowerEttore Budassi0Carlo M. Carloni Calame1Marco Ghilardi2Andrea Gurgone3Guido Montagna4Mauro Moretti5Oreste Nicrosini6Fulvio Piccinini7Francesco P. Ucci8Dipartimento di Fisica, Università di PaviaINFN, Sezione di PaviaDipartimento di Fisica, Università di PaviaDipartimento di Fisica, Università di PaviaDipartimento di Fisica, Università di PaviaDipartimento di Fisica e Scienze della Terra, Università di FerraraINFN, Sezione di PaviaINFN, Sezione di PaviaDipartimento di Fisica, Università di PaviaAbstract The pion pair production in e + e − annihilation at flavour factories plays a crucial role in the determination of the hadronic contribution to the muon anomalous magnetic moment. The recent CMD-3 measurement of the pion form factor via energy scan displays a significant difference with the previous experimental determinations. In order to contribute to an improved theoretical description and simulation of energy scan experiments, we present a calculation of the e + e − → π + π −(γ) hadronic channel at next-to-leading order matched to a Parton Shower algorithm in QED and sQED. According to the recent advances in the literature, particular attention is paid to the treatment of the pion composite structure in loop diagrams beyond the commonly used factorised sQED approach, as well as to the modelling of multiple photon radiation through the Parton Shower algorithm. In particular, we carry out a detailed discussion on the inclusion of the pion form factor in the virtual sQED corrections according to two independent methods, inspired by the generalised vector meson dominance model and the dispersive approach, respectively. We find the two methods to be in remarkable agreement. We show phenomenological results for inclusive and differential observables which are relevant for precision energy scan measurements, focusing on the impact of the radiative corrections and the effect of the various approaches for the treatment of the pion form factor. Our calculation is implemented in an updated version of the Monte Carlo event generator BabaYaga@NLO, that can be used for fully exclusive simulations in data analysis.https://doi.org/10.1007/JHEP05(2025)196Parton ShowerPrecision QEDProperties of HadronsHigher Order Electroweak Calculations |
| spellingShingle | Ettore Budassi Carlo M. Carloni Calame Marco Ghilardi Andrea Gurgone Guido Montagna Mauro Moretti Oreste Nicrosini Fulvio Piccinini Francesco P. Ucci Pion pair production in e + e − annihilation at next-to-leading order matched to Parton Shower Journal of High Energy Physics Parton Shower Precision QED Properties of Hadrons Higher Order Electroweak Calculations |
| title | Pion pair production in e + e − annihilation at next-to-leading order matched to Parton Shower |
| title_full | Pion pair production in e + e − annihilation at next-to-leading order matched to Parton Shower |
| title_fullStr | Pion pair production in e + e − annihilation at next-to-leading order matched to Parton Shower |
| title_full_unstemmed | Pion pair production in e + e − annihilation at next-to-leading order matched to Parton Shower |
| title_short | Pion pair production in e + e − annihilation at next-to-leading order matched to Parton Shower |
| title_sort | pion pair production in e e annihilation at next to leading order matched to parton shower |
| topic | Parton Shower Precision QED Properties of Hadrons Higher Order Electroweak Calculations |
| url | https://doi.org/10.1007/JHEP05(2025)196 |
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