Document Type

Article

Publication Date

2021

DOI

10.1103/PhysRevLett.127.262501

Publication Title

Physical Review Letters

Volume

127

Issue

26

Pages

262501 (1-7)

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 < Q2 < 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.

Comments

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

Original Publication Citation

Chatagnon, P., Niccolai, S., Stepanyan, S. ... Zachariou, N., Zhang, J., & Zhao, Z.W. (2021). First measurement of timelike compton scattering. Physical Review Letters, 127 (26), 1-7, Article 262501. https://doi.org/10.1103/PhysRevLett.127.262501

ORCID

0000-0001-7282-8120 (Hyde), 0000-0003-2243-6836 (Kuhn), 0000-0002-3598-4594 (Pandey)

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