Speaker
Description
In the recent years COMPASS at CERN has started to investigate the
proton structure using exclusive reactions like Deeply Virtual Compton
Scattering (DVCS), where high energy muons are scattered off a hydrogen
target. This reaction allows to access Generalised Parton Distributions
and thus the 3-dimensional structure of the proton. From a pilot
measurement in 2012 first results were obtained for the dependence of
the DVCS cross section on the momentum transfer. The exponential slope
of this cross section is related to the transverse extension of the
parton distributions in the nucleon.
Further investigations of the proton structure are proposed for the time
after the LS2 shutdown of the CERN accelerator complex. To obtain new
input in the current puzzle of the proton radius we plan a measurement
of elastic muon-proton scattering using the CERN high energy muon
beam. As will be discussed such a measurement is complementary and
can reach the same precision as the planned experiments at Mainz and
PSI using elastic scattering of low energy electrons and muons,
respectively, but with different sources of systematic uncertainties.
