M. Derrick et al., EXCLUSIVE RHO(0) PRODUCTION IN DEEP-INELASTIC ELECTRON-PROTON SCATTERING AT HERA, Physics letters. Section B, 356(4), 1995, pp. 601-616
The exclusive production of rho(0) mesons in deep inelastic electron-p
roton scattering has been studied using the ZEUS detector Cross sectio
ns have been measured in the range 7 < Q(2) < 25 GeV2 for gammap cent
re of mass (c.m.) energies from 40 to 130 GeV. The gammap --> rho(0)p
cross section exhibits a Q(-(4.2+/-0.8-0.5+14)) dependence and bath l
ongitudinally and transversely polarised rho(0)'s are observed. The ga
mmap --> rho(0)p cross section rises strongly with increasing c.m. en
ergy, when compared with NMC data at lower energy, which cannot be exp
lained by production through soft pomeron exchange. The data are compa
red with perturbative QCD calculations where the rise in the cross sec
tion reflects the increase in the gluon density at low x.