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

Extended HQEFT Lagrangian and currents

From the tree-level heavy quark effective Lagrangian keeping particle-antiparticle mixed sectors we derive the vector current coupling to a hard gluonic field allowing for heavy quark-antiquark pair annihilation and creation.Comment: Talk given at 4th International Conference on Hyperons, Charm and Beauty Hadrons, Valencia, Spain, 27-30 Jun 2000. LaTeX, 4 pages, 1 EPS figur

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

Searching for BcB_c mesons in the ATLAS experiment at LHC

We discuss the feasibility of the observation of the signal from $B_c$ mesons in the ATLAS experiment of the LHC collider at a luminosity of ${\approx}\ 10^{33}$cm$^{-2}$s$^{-1}$. In particular we address the decay mode$B_c{\rightarrow}J/\psi \pi$followed by the leptonic decay$J/\psi{\rightarrow}\mu^+\mu^-$, which should permit an accurate measurement of the$B_c$mass. We performed a Monte Carlo study of the signal and background concluding that a precision of$40$MeV for the$B_c$ mass could be achieved after one year of running.Comment: Latex,7 pages including 3 uuencoded Postscript figures appended at the end of the latex fil

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

Study of Bc --> J/psi pi, etac pi decays with perturbative QCD approach

The Bc --> J/psi pi, etac pi decays are studied with the perturbative QCD approach. It is found that form factors and branching ratios are sensitive to the parameters w, v, f_J/psi and f_etac, where w and v are the parameters of the charmonium wave functions for Coulomb potential and harmonic oscillator potential, respectively, f_J/psi and f_etac are the decay constants of the J/psi and etac mesons, respectively. The large branching ratios and the clear signals of the final states make the Bc --> J/psi pi, etac pi decays to be the prospective channels for measurements at the hadron collidersComment: 21 pages, revtex

Exclusive c -> s, d Semileptonic Decays of Spin-1/2 and Spin-3/2 cb Baryons

We present results for exclusive semileptonic decay widths of ground state spin-1/2 and spin-3/2 cb baryons corresponding to a c -> s, d transition at the quark level. The relevance of hyperfine mixing in spin-1/2 cb baryons is shown. Our form factors are compatible with heavy quark spin symmetry constraints obtained in the infinite heavy quark mass limit

J/\psi production through resolved photon processes at e+ e- colliders

We consider J/psi photoproduction in e+ e- as well as linear photon colliders. We find that the process is dominated by the resolved photon channel. Both the once-resolved and twice-resolved cross-sections are sensitive to (different combinations of) the colour octet matrix elements. Hence, this may be a good testing ground for colour octet contributions in NRQCD. On the other hand, the once-resolved J/psi production cross-section, particularly in a linear photon collider, is sensitive to the gluon content of the photon. Hence these cross-sections can be used to determine the parton distribution functions, especially the gluon distribution, in a photon, if the colour octet matrix elements are known.Comment: Added a figure on parametrisation dependence of photonic parton densities and some reference