Related papers: Prompt Upsilon and Psi Production at LEP
Gluon fragmentation represents the dominant source of high energy prompt quarkonia at hadron colliders. Fragmentation approximations break down, however, when a quarkonium's transverse momentum becomes comparable to its mass. In this paper,…
We consider the energy and the polar angle distributions of J/\psi's produced via the color-singlet and the color-octet (^3S_1^{(8)}) mechanisms in Z^0 \to J/\psi +X at LEP. Since both distributions of the J/\psi produced via color-octet…
We report that, unlike most inclusive quarkonium-production processes, the production rate for p p -> J/psi+Upsilon+X dominantly depends on two not well-known long-distance nonrelativistic QCD matrix elements, <O_8^{J/psi}(^3S_1)> and…
It has been proposed that the large cross sections for prompt $\psi$, $\psi'$, and $\chi_c$ production at the Fermilab Tevatron $p\bar p$ collider can be explained by a dominant color-octet term in the fragmentation function for a gluon to…
We calculate the lowest order hadronic cross sections for producing colored heavy quark-antiquark pairs in $L=S=0$ and $L=S=1$ configurations. Such $Q\Qbar[{}^1S_0^{(8)}]$ and $Q\Qbar[{}^3P_J^{(8)}]$ states hadronize into $\psi_\Q$…
The conventional color-singlet model was challenged by the recent data on quarkonium production. Discrepancies in production rates were observed at the Tevatron, at LEP, and in fixed-target experiments. The newly advocated color-octet…
We investigate the SM Higgs decays into heavy quarkonia J/\psi and \Upsilon in both color-singlet and color-octet mechanisms. It is found that in J/\psi production the contribution through color-octet processes overwhelm that in…
We calculate the polarisation of $\psi$'s and $\Upsilon$'s produced by the fragmentation of heavy quarks. We find that fragmentation to transversely aligned quarkonium is slightly enhanced relative to longitudinally polarised. This net…
The production rate of prompt $\psi'$'s at large transverse momentum at the Tevatron is larger than theoretical expectations by about a factor of 30. As a solution to this puzzle, we suggest that the dominant $\psi'$ production mechanism is…
We investigate the pair production of S-wave heavy quarkonium at the LHC in the color-singlet mechanism (CSM) and estimate the contribution from the gluon fragmentation process in the color-octet mechanism (COM) for comparison. With the…
We consider the prompt hadroproduction of J/psi, psi' and the Upsilon (1S,2S,3S) states caused by the fusion of a symmetric colour-octet two-gluon state and an additional gluon. The cross sections are calculated in leading-order…
We study contributions from color-octet quarkonium formation mechanisms to $p_\perp$-integrated $\psi'$ production cross sections in pion-nucleon reactions. The observed polarization of the $\psi'$ is not reproduced by the lowest-order…
The precise mechanism for production of quarkonium at hadron colliders is still an open question. Within non-relativistic quantum chromodynamics, quarkonium production cross sections can be factorized into short-distance, perturbative…
To test a possible color-octet contribution of heavy quarkonium productions, we propose $\psi$'-productions for small-$p_T$ regions, where the color-singlet $\psi$' state cannot be produced by the gluon-gluon fusion owing to charge…
With nonrelativistic QCD factorization, we calculate the $\Upsilon(1S)$ prompt production at hadron colliders at next-to-leading order in $\alpha_s$. In addition to the color-singlet contribution, color-octet channels (especially the P-wave…
Using data collected with the CLEO III detector at the Cornell Electron Storage Ring, we have compared proton, lambda (charged conjugate modes are implicit) and meson (phi and f2(1270)) production observed in gluon fragmentation vs. quark…
Color-octet contributions to the associate $J/\psi+\gamma$ production are found to be negligible, compared to the ordinary color-singlet contribution. Within the color-singlet model the $J/\psi+\gamma$ production in the leading order is…
This thesis can be divided into several parts. The first one consists in a detailed historical review of quarkonium physics, centered on the different production models successively introduced. Then comes a review of the currently available…
Color-octet contributions to the associate J/psi+gamma hadroproduction are studied in detail, and found to be negligible, compared to the ordinary color-singlet contribution. Within the color-singlet model the J/psi+gamma production in the…
The photoproduction of quarkonium in coherent hadron-hadron (pp/pA/AA$) interactions for LHC energies is an important tool to investigate the QCD dynamics at high energies. In this paper we estimate the integrated cross section and rapidity…