Photoproduction of heavy vector mesons at HERA – a test field for diffraction

R. Fiore; L. L. Jenkovszky; F. Paccanoni

doi:doi:10.1007/s100529900046

EPJ

a
b
c
d
e
ap
st
h
plus
ds
pv
ti
qt
am
n

2024 Impact factor 4.8

Particles and Fields

Eur. Phys. J. C 10, 461-467
DOI 10.1007/s100529900046

Photoproduction of heavy vector mesons at HERA - a test field for diffraction

R. Fiore¹ - L. L. Jenkovszky² - F. Paccanoni³

¹ Dipartimento di Fisica, Università della Calabria, Istituto Nazionale di Fisica Nucleare, Gruppo collegato di Cosenza,
Arcavacata di Rende, I-87030 Cosenza, Italy (e-mail: FIORE@CS.INFN.IT)
² Bogoliubov Institute for Theoretical Physics, Academy of Sciences of the Ukrain, 252143 Kiev, Ukrain
(e-mail: JENK@GLUK.APC.ORG)
³ Dipartimento di Fisica, Università di Padova, Istituto Nazionale di Fisica Nucleare, Sezione di Padova, F. Marzolo 8,
I-35131 Padova, Italy (e-mail: PACCANONI@PADOVA.INFN.IT)

Received: 11 January 1999 / Published online: 8 September 1999

Abstract
Exclusive diffractive photoproduction of heavy vector mesons (V= $\phi, J/\psi$ , and $\Upsilon$ ) at HERA is studied in a model employing a dipole Pomeron exchange (P) with an inelastic $\gamma PV$ vertex. The model is fitted to the data on ${\mathrm{d}\sigma/\mathrm{d}t}$ , B, and $\sigma_{\mathrm{e}l}$ for Q²=0 and beyond the threshold region. The elastic cross sections for both $\phi$ and $J/\psi$ photoproduction show a moderate increase within the HERA energy region. The flattening of the slope B(s) (indicating little or no shrinkage) for $J/\psi$ is not correlated with the slope of the Pomeron trajectory. Estimates for $\Upsilon$ photoproduction at HERA are given.