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Article
Report number arXiv:2005.14471 ; DESY-20-080
Title Measurement of exclusive π+π and ρ0 meson photoproduction at HERA
Related titleMeasurement of Exclusive π+π and ρ0 Meson Photoproduction at HERA
Author(s) H1 Collaboration  Zeige alle 138 Autoren
Publication 2020-12-23
Imprint 2020-05-29
Number of pages 54
Note 74 pages, 20 figures, 23 tables, accepted by EPJC. Figure numbering updated. Ancillary material has been updated
In: Eur. Phys. J. C 80 (2020) 1189
DOI 10.1140/epjc/s10052-020-08587-3
Subject category hep-ph ; Particle Physics - Phenomenology ; hep-ex ; Particle Physics - Experiment
Accelerator/Facility, Experiment DESY HERA H1
Abstract Exclusive photoproduction of ρ0(770) mesons is studied using the H1 detector at the ep collider HERA. A sample of about 900000 events is used to measure single- and double-differential cross sections for the reaction γpπ+πY. Reactions where the proton stays intact (mY=mp) are statistically separated from those where the proton dissociates to a low-mass hadronic system (mp<mY<10 GeV). The double-differential cross sections are measured as a function of the invariant mass mππ of the decay pions and the squared 4-momentum transfer t at the proton vertex. The measurements are presented in various bins of the photon-proton collision energy Wγp. The phase space restrictions are 0.5<mππ<2.2 GeV, |t|<1.5 GeV2, and 20<Wγp<80 GeV. Cross section measurements are presented for both elastic and proton-dissociative scattering. The observed cross section dependencies are described by analytic functions. Parametrising the mππ dependence with resonant and non-resonant contributions added at the amplitude level leads to a measurement of the ρ0(770) meson mass and width at mρ=770.8 2.7+2.6 (tot) MeV and Γρ=151.3 3.6+2.7 (tot) MeV, respectively. The model is used to extract the ρ0(770) contribution to the π+π cross sections and measure it as a function of t and Wγp. In a Regge asymptotic limit in which one Regge trajectory α(t) dominates, the intercept α(t=0)=1.0654 0.0067+0.0098 (tot) and the slope α(t=0)=0.233 0.074+0.067 (tot) GeV2 of the t dependence are extracted for the case mY=mp.
Copyright/License preprint: (License: arXiv nonexclusive-distrib 1.0)
publication: © 2020-2024 The Author(s) (License: CC-BY-4.0), sponsored by SCOAP³



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