First Measurement of Timelike Compton Scattering.

DOI

10.1103/PhysRevLett.127.262501

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 < Q'2 < 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.

Document Type

Article

Publication Date

12-22-2021

Publisher Statement

Copyright © 2021, APS Physics.

DOI: https://doi.org/10.1103/PhysRevLett.127.262501.

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