Speaker
Hamlet Zohrabian
Description
The production of photons at very small angles with respect to the proton
beam direction is studied in deep-inelastic positron-proton scattering at
HERA. The data are taken with the H1 detector in the years 2006 and 2007
and correspond to an integrated luminosity of $126 \mathrm{pb}^{-1}$. The
analysis covers the range of negative four momentum transfer squared at the
positron vertex $6<Q^2<100$ GeV$^2$ and inelasticity $0.05<y<0.6$. Cross
sections are measured for the most energetic photon with pseudorapidity
$\eta>7.9$ as a function of its transverse momentum $p_T^{lead}$ and
longitudinal momentum fraction of the incoming proton $x_L^{lead}$. In
addition, the cross sections are studied as a function of the sum of the
longitudinal momentum fraction $x_L^{sum}$ of all photons in the
pseudorapidity range $\eta>7.9$. The cross sections are normalised to the
inclusive deep-inelastic scattering cross section and compared to the
predictions of models of deep-inelastic scattering and models of the
hadronic interactions of high energy cosmic rays.
