production at the LHC

Abstract

We firstly re-examine hadroproduction of prompt J/ψ's at the Fermilab Tevatron finding that those colour-octet matrix elements presented in literature are systematically overestimated due to the overlooking of the effective primordial transverse momentum of partons (i.e. dynamically generated via initial-state radiation). We estimate the size of these effects using different parton distribution functions in a Monte Carlo framework. Finally, we extrapolate up to LHC energies making a prediction on the expected p t differential cross-section for charmonium.

Erratum: PolarizedJ/ψproduction in deep inelastic scattering at DESY HERA [Phys. Rev. D 63, 034017 (2001)]

“…However, there are other sets of parameterizations for the two color-octet matrix elements O ψ 8 ( 1 S 0 ) and O ψ 8 ( 3 P 0 ) in the literature [12,13]. With these rather small values for the two color-octet matrix elements [12,13], the above predictions of α in the NRQCD FA will be changed. For example, if we follow the values obtained in [13], the two equations of (23) and (24) will be changed to…”

“…Recently, the photoproduction data from HERA [8,9] put a question about the color-octet predictions for the inelastic photoproduction of J/ψ [10,11] (possible solutions for this problem have been suggested in [12][13][14][15]). Most recently, the CDF collaboration have reported their preliminary measurements on the polarizations of the promptly produced charmonium and bottomonium states [16], which appear not to support the color-octet predictions that the directly produced S-wave quarkonia have transverse polarization at large p T [17,18].…”

New extraction of color-octet NRQCD matrix elements from charmonium hadroproduction

“…In a series of previous papers [1][2][3][4] we analyzed charmonium hadroproduction in the light of the color-octet model [5]. We employed a Monte Carlo generator (PYTHIA 5.7) [6] to assess the importance of some higher-order QCD effects.…”

Bottomonium production at the Tevatron and the LHC

“…In a series of previous papers [2,3,4,5] we examined charmonium hadroproduction in a Monte Carlo framework, using PYTHIA 5.7 [6] event generator with the colour-octet model (COM) [7] implemented in. Basically, such a production mechanism is based on the formation of an intermediate coloured state during the hard partonic interaction, evolving non-perturbatively into physical heavy resonances in the final state with certain probabilities governed by NRQCD [8].…”