We present the first measurement of the timelike Compton scattering process, γp→p′γ∗(γ∗→e+e-), obtained with the CLAS12 detector at Jefferson Lab. The photon beam polarization and the decay lepton angular asymmetries are reported in the range of timelike photon virtualities 2.25<9 GeV2, squared momentum transferred 0.1<-t<0.8 GeV2, and average total center-of-mass energy squared s=14.5 GeV2. The photon beam polarization asymmetry, similar to the beam-spin asymmetry in deep virtual Compton scattering, is sensitive to the imaginary part of the Compton form factors and provides a way to test the universality of the generalized parton distributions. The angular asymmetry of the decay leptons accesses the real part of the Compton form factors and thus the D-term in the parametrization of the generalized parton distributions.

First Measurement of Timelike Compton Scattering

Bianconi, A.;Costantini, G.;Leali, M.;Mascagna, V.;Migliorati, S.;Venturelli, L.;
2021-01-01

Abstract

We present the first measurement of the timelike Compton scattering process, γp→p′γ∗(γ∗→e+e-), obtained with the CLAS12 detector at Jefferson Lab. The photon beam polarization and the decay lepton angular asymmetries are reported in the range of timelike photon virtualities 2.25<9 GeV2, squared momentum transferred 0.1<-t<0.8 GeV2, and average total center-of-mass energy squared s=14.5 GeV2. The photon beam polarization asymmetry, similar to the beam-spin asymmetry in deep virtual Compton scattering, is sensitive to the imaginary part of the Compton form factors and provides a way to test the universality of the generalized parton distributions. The angular asymmetry of the decay leptons accesses the real part of the Compton form factors and thus the D-term in the parametrization of the generalized parton distributions.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11379/558321
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