https://doi.org/10.1007/s100520100881
Theoretical physics
Soft and hard QCD dynamics in hadroproduction of charmonium
1
High Energy Physics, Uppsala University, Box 535, 75121, Uppsala, Sweden
2
Institute of Physics, Univ. Fed. do Rio Grande do Sul, Box 15051, CEP 91501-960, Porto Alegre, Brazil
3
Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22603, Hamburg, Germany
Both hard and soft QCD dynamics are important in charmonium production, as presented here through a next-to-leading order QCD matrix element calculation combined with the color evaporation model. The observed 
and 
distributions of 
in hadroproduction at fixed target and 
collider energies are reproduced. Quite similar results can also be obtained in a more phenomenologically useful Monte Carlo event generator where the perturbative production of 
pairs is instead obtained through leading order matrix elements and the parton shower approximation of the higher order processes. The soft dynamics may alternatively be described by the soft color interaction model, originally introduced in connection with rapidity gaps. We also discuss the relative rates of different charmonium states and introduce an improved model for mapping the continuous 
mass spectrum on the physical charmonium resonances
© Springer-Verlag Berlin Heidelberg / Società Italiana di Fisica, 2002
