Measurement of electromagnetic transition form factors in two-photon collisions at BESIII

10 Jun 2026, 12:20
20m
Scuola Normale Superiore, Aula Dini, Palazzo del Castelletto (Pisa)

Scuola Normale Superiore, Aula Dini, Palazzo del Castelletto

Pisa

Via del Castelletto, 11, 56126 Pisa PI

Speaker

Max Lellmann

Description

Electromagnetic transition form factors of light mesons are important inputs to the calculations of the hadronic light-by-light scattering contribution to the Standard Model prediction of the anomalous magnetic moment of the muon. However, data in the relevant regions of momentum transfer are scarce. The BESIII experiment at the $e^+ e^-$ collider BEPCII has collected the world's largest data sets in the tau-charm energy region, including, but not limited to more than 20 $fb^{-1}$ of data at a center-of-mass energy of 3.773 GeV/c^2. The data are analyzed for two-photon collisions in events of the type $e^+ e^-→e^+ e^- P$, with $P=π^0,η^{(') },f_1 (1285),π^0 π^0$, and $π^+ π^-$. The aim is to study the momentum dependence of the respective space-like electromagnetic transition form factors. In this presentation we discuss recent results and prospects of ongoing analyses.

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Author

Max Lellmann

Co-author

Fabrizio Umberto Bianchi (INFN - Torino)

Presentation materials