1 research outputs found
Measurement of the Generalized Polarizabilities of the Proton in Virtual Compton Scattering
We propose to conduct a measurement of the Virtual Compton Scattering
reaction in Hall C that will allow the precise extraction of the two scalar
Generalized Polarizabilities (GPs) of the proton in the region of
to . The Generalized Polarizabilities
are fundamental properties of the proton, that characterize the system's
response to an external electromagnetic (EM) field. They describe how easily
the charge and magnetization distributions inside the system are distorted by
the EM field, mapping out the resulting deformation of the densities in the
proton. As such, they reveal unique information regarding the underlying system
dynamics and provide a key for decoding the proton structure in terms of the
theory of the strong interaction that binds its elementary quark and gluon
constituents together. Recent measurements of the proton GPs have challenged
the theoretical predictions, particularly in regard to the electric
polarizability. The magnetic GP, on the other hand, can provide valuable
insight to the competing paramagnetic and diamagnetic contributions in the
proton, but it is poorly known within the region where the interplay of these
processes is very dynamic and rapidly changing.The unique capabilities of Hall
C, namely the high resolution of the spectrometers combined with the ability to
place the spectrometers in small angles, will allow to pin down the dynamic
signature of the GPs through high precision measurements combined with a fine
mapping as a function of . The experimental setup utilizes standard Hall C
equipment, as was previously employed in the VCS-I (E12-15-001) experiment,
namely the HMS and SHMS spectrometers and a 10 cm liquid hydrogen target. A
total of 59 days of unpolarized 75 electron beam with energy of 1100
MeV (6 days) and 2200 MeV (53 days) is requested for this experiment