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Register a new userInvestigating charmonium production at LHC with the p pbar final state
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We propose to investigate various charmonium states using their common decay channel to p pbar at LHC. Having the branching ratios for charmonium decaying into the p pbar final state measured or calculated, we propose to measure the charmonium production rate for both hadroproduction including soft-diffraction and inclusive production from b-hadron decays. We discuss the theoretical impacts in QCD of measuring different charmonium production rates and also the experimental prospects at LHCb, in particular, those for yet unmeasured eta_c and h_c.
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In this paper we summarize our recent results for low energy associated charmonium production cross sections, using 1) crossing symmetry, and 2) an explicit hadronic model. These predictions are of relevance to the planned charmonium and charmonium hybrid production experiment PANDA at GSI.
The QCD mechanisms underlying the exclusive strong decays and hadronic production amplitudes of charmonium remain poorly understood, despite decades of study and an increasingly detaled body of experimental information. One set of hadronic channels of special interest are those that include baryon-antibaryon states. These are being investigated experimentally at BES and CLEO-c in terms of their baryon resonance content, and are also of interest for the future PANDA experiment, in which charmonium and charmonium hybrids will be produced in p-pbar annihilation in association with light mesons. In this paper we develop a simple initial-state light meson emission model of the near-threshold associated charmonium production processes p pbar -> pi0 ccbar, and evaluate the differential and total cross sections for these reactions in this model. (Here we consider the ccbar states eta_c, J/psi, psi, chi_0 and chi_1.) The predicted near-threshold cross section for p pbar -> pi0 J/psi is found to be numerically similar to two previous theoretical estimates, and is roughly comparable to the (sparse) existing data for this process. The theoretical charmonium angular distributions predicted by this model are far from isotropic, which may be of interest for PANDA detector design studies.
We have performed a systematic study of $J/psi$ and $psi(2S)$ production in $p-p$ collisions at different LHC energies and at different rapidities using the leading order (LO) non-relativistic QCD (NRQCD) model of heavy quarkonium production. We have included the contributions from $chi_{cJ}$ ($J$ = 0, 1, 2) and $psi(2S)$ decays to $J/psi$. The calculated values have been compared with the available data from the four experiments at LHC namely, ALICE, ATLAS, CMS and LHCb. In case of ALICE, inclusive $J/psi$ and $psi(2S)$ cross-sections have been calculated by including the feed-down from $B$ meson using Fixed-Order Next-to-Leading Logarithm (FONLL) formalism. It is found that all the experimental cross-sections are well reproduced for $p_T >$ 4 GeV within the theoretical uncertainties arising due to the choice of the factorization scale. We also predict the transverse momentum distributions of $J/psi$ and $psi(2S)$ both for the direct and feed-down processes at the upcoming LHC energies of $sqrt{s} =$ 5.1 TeV and 13 TeV for the year 2015.
The chromopolarizability of a quarknonium describes the quarknoniums interaction with soft gluonic fields and can be measured in the heavy quarkonium decays. Within the framework of dispersion theory which consider the $pipi$ final state interaction (FSI) model-independently, we analyze the transition $psi^primeto J/psipi^+pi^-$ and obtain the chromopolarizability $alpha_{psi^prime psi}$ and the parameter $kappa$. It is found that the $pipi$ FSI plays an important role in extracting the chromopolarizability from the experimental data. The obtained chromopolarizability with the FSI is reduced to about 1/2 of that without the FSI. With the FSI, we determine the chromopolarizability $|alpha_{psi^primepsi}|=(1.44pm 0.02)$ GeV$^{-3}$ and the parameter $kappa=0.139pm 0.005.$ Our results could be useful in studying the interactions of charmonium with light hadrons.
The cross sections for the charmonium production processes p pbar -> m Psi, where m is a light meson and Psi is a charmonium state, are of great interest for the planned p-pbar experiment PANDA. In this paper we estimate these cross sections using known results for the decays Psi -> m p pbar which are related to these reactions by crossing. In lieu of detailed experimental data on the decay Dalitz plots, we assume a constant amplitude as a first approximation; this implies a simple relation between the cross sections and decay widths. The single measured exclusive cross section of this type is p pbar -> pi0 J/psi, which was reported by E760 to be 130 +/- 25 pb near sqrt(s) = 3.5-3.6 GeV. In comparison, our constant amplitude estimate is about 300 pb at this energy. This suggests that our approach is useful as a simple estimate, but should be refined through detailed modeling of resonances and other energy-dependent effects in the experimental Psi -> m p pbar Dalitz plots.
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