Bottomonium Production at the Tevatron and the LHC

Inclusive bottomonium hadroproduction at the Tevatron is firstly examined in a Monte Carlo framework with the colour-octet mechanism implemented in the event generation. We extract some NRQCD colour-octet matrix elements relevant for $\Upsilon(1S)$ hadroproduction. Remarkably we find a quite small contribution (compatible with zero) from feeddown of $\chi_{bJ}$ states produced through the colour-octet mechanism: $\Upsilon(1S)$ indirect production via $\chi_{bJ}$ decays should be mainly ascribed to the colour-singlet model. Finally we extrapolate to LHC energies to predict prompt $\Upsilon(1S)$ production rates.Comment: LaTeX, 11 pages, 6 EPS figure

Bottomonia Hadroproduction

We analyze Tevatron data of bottomonium hadroproduction in the framework of the colour-octet model (COM) implemented in the event generator PYTHIA using CTEQ4L PDF taking into account initial-state radiation of gluons and Altarelli-Parisi evolution of final-state gluons. We obtain new values for the colour-octet matrix elements relevant to this production process for the Upsilon(nS) family (n=1,2,3), finding that the ^1S_0^{(8)}+^3P_J^{(8)} contributions are not needed in the fit. We show the different contributions to Upsilon(1S) production at Tevatron for p_T>8 GeV, comparing them with CDF data. Finally we extrapolate to LHC energies to predict Upsilon(nS) production rates.Comment: Talk given at 4th International Conference on Hyperons, Charm and Beauty Hadrons, Valencia, Spain, 27-30 Jun 2000. LaTeX, 4 pages, 4 EPS figure

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

We re-analyze Tavatron data on charmonium hadroproduction in the framework of the color-octet model implemented in the event generator PYTHIA taking into account initial-state radiation of gluons and Altarelli-Parisi evolution of final-state gluons fragmenting into cc¯ pairs. We obtain new values for the color-octet matrix elements relevant to this production process. We discuss the sensitivity of our results to the transverse momentum lower cut-off employed in the generation to avoid the problematic pt→0 region, arguing about the reliability of our previous extraction of the NRQCD matrix elements for the 3S(8)1 and 1S(8)0+3P(8)J contributions. Finally we extrapolate to LHC energies to get predictions on the J/ψ direct production rate

Results from Bottomonia Production at the Tevatron and Prospects for the LHC

We extend our previous analysis on inclusive heavy quarkonia hadroproduction to the whole Upsilon(nS) (n=1,2,3) resonance family. We use a Monte Carlo framework with the colour-octet mechanism implemented in the PYTHIA event generator. We include in our study higher order QCD effects such as initial-state emission of gluons and Altarelli-Parisi evolution of final-state gluons. We extract some NRQCD colour-octet matrix elements relevant for Upsilon(nS) (n=1,2,3) hadroproduction from CDF data at the Fermilab Tevatron. Then we extrapolate to LHC energies to predict prompt bottomonia production rates. Finally, we examine the prospect to probe the gluon density in protons from heavy quarkonia inclusive hadroproduction at high transverse momentum and its feasibility in LHC general-purpose experiments.Comment: LaTeX, 30 pages, 30 EPS figure

J/psi production at the Tevatron and HERA: the effect of k_T smearing

We study the effects of intrinsic transverse momentum smearing on J/psi production both at the Tevatron and at HERA. For the case of large-p_T J/psi production at the Tevatron, the effects due to k_T smearing are mild. On the other hand, inelastic J/psi photoproduction at HERA is very sensitive to the k_T smearing and, in fact, with a reasonable value of it is possible to resolve the large-z discrepancy seen by comparing non-relativistic QCD (NRQCD) predictions with the HERA data. We conclude that, with the present kinematic cuts, photoproduction at HERA is not a good test of NRQCD.Comment: 11 pages, LaTeX, 2 figures, uses epsfi

Colour Octet effects in Quarkonium Physics

The importance of including colour octet contributions in describing decay and production of quarkonium states is briefly discussed for two cases : the radiative decays of the $\Upsilon$ and the production of $J/\psi$ in the inclusive $B$ decays. It is shown how information on the non-perturbative matrix elements can be obtained by comparing the theoretical expressions computed at next-to-leading order in $\alpha_s$ with the experimental data.Comment: 4 pages, Latex (espcrc2.sty), 1 figure. Talk presented at QCD'98, Montpellier, July 2-8, 1998; to appear in Nucl. Phys. B (Proc. Suppl.

J/psi Production at the LHC

We firstly examine hadroproduction of prompt J/psi's at the Fermilab Tevatron in a Monte Carlo Framework by means of the event generator PYTHIA 5.7 in which those colour-octet matrix elements processes relevant for charmonium production have been implemented accordingly. We find that colour-octet matrix elements presented in literature from p-pbar collider data are systematically overestimated due to overlooking of the effective primordial transverse momentum of partons (i.e. including higher-order QCD effects). We estimate the size of these effects using different parton distribution functions. Finally, after normalization to Tevatron data, we extrapolate up to LHC energies making a prediction on the expected pt differential cross-section for charmonium.Comment: 4 pages, LaTex, 3 Figures included in the text, Contribution to the 2nd Int. Conference on Hyperons, charm and beauty hadrons (Montreal, Aug 27-30, 1996

J/psi Inclusive Production in ep Deep-Inelastic Scattering at DESY HERA

We calculate the cross section of J/psi plus jet associated production in ep deep-inelastic scattering within the factorization formalism of nonrelativistic quantum chromodynamics. Our analytic results disagree with previous analyses, both for the colour-singlet and colour-octet channels. Our theoretical predictions agree reasonably well with recent data taken by the H1 Collaboration at DESY HERA, significantly better than those obtained within the colour-singlet model.Comment: 27 pages (Latex), 9 figures (Postscript), to appear in Nucl. Phys.

Quarkonium production and NRQCD matrix elements

Most recent calculations of quarkonium production are based on the NRQCD factorization formalism. This formalism is reviewed. To make predictions about specific cross section, universal NRQCD matrix elements need to be extracted from experiments. Extractions from different experimental situations are compared, with some emphasis on the extraction from LEP.Comment: 6 pages, 1 figure, talk given at 4th International Conference on Hyperons, Charm and Beauty Hadrons, Valencia, Spain, 27-30 Jun 200

Latest Highlights from the H1 Collaboration

Recent data obtained in ep collisions at HERA by the H1 collaboration are presented: searches for new phenomena beyond the Standard Model, measurement of the inclusive neutral and charged current cross sections and of the proton structure function, determination of the gluon density in the proton and photon from jet productions, measurement and interpretation of event shapes in the current region of the Breit frame, test of the parton evolution at low x and of the diffractive production mechanism.Comment: 17 pages, 21 figures, plenary talk at 7th International Workshop on Deep Inelastic Scattering and QCD, Berlin-Zeuthen (Germany), April 199