Speaker
Description
Time-Like Compton Scattering (TCS) is a hard, exclusive scattering process, in which a real photon scatters from a target nucleon, producing a virtual
(timelike) photon, which couples to a lepton pair in the final state [1].
TCS, via cross section and asymmetry observables, gives access to Gener-
alised Parton Distributions (GPDs), through which we can develop a tomo-
graphic mapping of nucleon structure, and access information pertaining to
the mechanical properties of hadrons, such as shear forces and pressure dis-
tributions. The first published result of TCS in 2021 [2] was measured on an
unpolarised hydrogen target. This work seeks to present another first measure-
ment by performing the analysis on a longitudinally polarised target, from which
Target Spin Asymmetries (TSA) and Double Spin Asymmetries (DSA) can be
measured, allowing access to the GPDs $H$ and $\tilde{H}$ .
To this end, I present a preliminary extraction of a TCS signal from recent
data taking at Jefferson Lab during Run Group C, using quasi-real photons
from the 10.6 GeV electron beam and the CLAS12 detector.
References
[1] E.R. Berger, M. Diehl, and B. Pire. Timelike compton scattering: exclu-
sive photoproduction of lepton pairs. The European Physical Journal C,
23(4):675–689, apr 2002.
[2] P. Chatagnon et al. First measurement of timelike compton scattering. Phys. Rev. Lett., 127:262501, Dec 2021.
