Speaker
Sergey Levonian
(Deutsches Elektronen-Synchrotron (DE))
Description
The first measurement of exclusive photoproduction of rho meson
associated with the leading neutron at HERA is presented.
The data are taken with the H1 detector in the years 2006-2007
and correspond to an integrated luminosity of 1.16 pb-1.
The rho mesons are reconstructed from decay pions in the central
tracking chamber, while the leading neutrons, carrying a large
fraction of the incoming proton momentum x_L>0.4, are detected in the
Forward Neutron Calorimeter. The phase space of the measurement is
restricted to by photon virtualities Q$^{2}$<2 GeV$^{2}$, total energies of the
gamma-p system 20 < W_gp < 100 GeV and polar angles of the leading
neutrons, theta_n < 0.75 mrad. The cross section of the reaction
gamma+p -> rho+n+Y, where Y is a small mass system escaping undetected
in the proton direction, is measured as a function of the neutron
energy, the invariant mass of the pi+pi- system and the
transverse momentum and the pseudorapidity of the rho meson. The data are
interpreted in terms of a double peripheral process, involving a
pion exchange at the proton vertex followed by elastic photoproducton
of a rho meson on a virtual pion.
Authors
Karin Daum
(University of Wuppertal/DESY)
Stefan Schmitt
(Deutsches Elektronen-Synchrotron (DE))
