T. Ahmed et al., EXPERIMENTAL-STUDY OF HARD PHOTON RADIATION PROCESSES AT HERA, Zeitschrift fur Physik. C, Particles and fields, 66(4), 1995, pp. 529-542
We present an experimental study of the ep --> e gamma + p and ep -->
e gamma + X processes using data recorded by the H1 detector in 1993 a
t the electron-proton collider HERA. These processes are employed to m
easure the luminosity with an accuracy of 4.5 %. A subsample of the ep
--> e gamma + X events in which the hard photon is detected at angles
theta'(gamma) less than or equal to 0.45 mrad with respect to the inc
ident electron direction is used to verify experimentally the size of
radiative corrections to the ep --> eX inclusive cross section and to
investigate the structure of the proton in the Q(2) domain down to 2 G
eV2, lower than previously attained at HERA.