Study of dimuon production in photon-photon collisions and measurement of QED photon structure functions at LEP

The DELPHI Collaboration P. Abreu; et al.

doi:doi:10.1007/s100520100592

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2023 Impact factor 4.2

Particles and Fields

Eur. Phys. J. C 19, 15-28
DOI: 10.1007/s100520100592

Study of dimuon production in photon-photon collisions and measurement of QED photon structure functions at LEP

The DELPHI Collaboration
P. Abreu²² and et al.

²² LIP, IST, FCUL - Av. Elias Garcia, 14-1^o, 1000 Lisboa Codex, Portugal

(Received: 23 February 2000 / Revised version: 7 December 2000 / Published online: 23 February 2001 -© Springer-Verlag 2001)

Abstract
Muon pair production in the process $e^+e^-\to e^+e^-\mu^+\mu^-$ is studied using the data taken at LEP1 ( $\sqrt{s}\simeq m_Z$ ) with the DELPHI detector during the years 1992-1995. The corresponding integrated luminosity is 138.5 pb^-1. The QED predictions have been tested over the whole Q² range accessible at LEP1 (from several GeV²/c⁴ to several hundred GeV²/c⁴) by comparing experimental distributions with distributions resulting from Monte Carlo simulations using various generators. Selected events are used to extract the leptonic photon structure function $F_2^\gamma$ . Azimuthal correlations are used to obtain information on additional structure functions, $F_A^\gamma$ and $F_B^\gamma$ , which originate from interference terms of the scattering amplitudes. The measured ratios $F_A^\gamma/F_2^\gamma$ and $F_B^\gamma/F_2^\gamma$ are significantly different from zero and consistent with QED predictions.