Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userStudying the Pc(4450) resonance in J/psi photoproduction off protons
212
0
0.0
(
0
)
Added by
Astrid Nathalie Hiller Blin
Publication date
2018
fields
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
The LHCb has reported the observation of a resonancelike structure, the Pc(4450), in the J/psi p invariant masses. In our work, we discuss the feasibility of detecting this structure in J/psi photoproduction, e.g. in the measurements that have been approved for the experiments in Hall A/C and in Hall B with CLAS12 at JLab. Also the GlueX Collaboration has already reported preliminary results. We take into account the experimental resolution effects, and perform a global fit to world J/psi photoproduction data in order to study the possibility of observing the Pc(4450) signal in future JLab data. We present a first estimate of the upper limit for the branching ratio of the Pc(4450) into the J/psi p channel, and we study the angular distributions of the differential cross sections. This will shed light on the nature and couplings of the Pc(4450) structure in the future photoproduction experiments.
rate research
Read More
A resonance-like structure, the P_c(4450), has recently been observed in the J/psi p spectrum by the LHCb collaboration. We discuss the feasibility of detecting this structure in J/psi photoproduction in the CLAS12 experiment at JLab. We present a first estimate of the upper limit for the branching ratio of the P_c(4450) to J/psi p. Our estimates, which take into account the experimental resolution effects, predict that it will be possible to observe a sizable cross section close to the J/psi production threshold and shed light on the P_c(4450) resonance in the future photoproduction measurements.
We study the photoproduction of the vector mesons $Phi$ and $J/Psi$ off a proton in the kinematical regime of large energies and scattering angles within the framework of perturbative QCD. Our investigations are based on the hard scattering approach. This means that the hadrons are replaced by their valence Fock states and scattering on the partonic level is described by tree graphs in which the large transferred momentum is redistributed between the valence partons via the exchange of hard gluons. We find that the unpolarized photoproduction cross sections are dominated by Compton-scattering-like graphs in which the photon couples to the proton, whereas vector-meson-dominance-like graphs, in which the photon fluctuates into the heavy quark-antiquark pair which then exchanges two gluons with the proton, play a minor role. We give explicit predictions for unpolarized scattering cross sections and compare them with experimental data where possible.
The $O(v^2)$ relativistic correction for inelastic $J/psi$ photoproduction, in which heavy quark pairs are in the dominant Fock state of the quarkonium, is studied in the framework of NRQCD factorization. An assessment of its significance, particularly in comparison to the color octet contributions, is made. It is found that the impact on the energy distribution is negative in certain regions of phase space. The predictions are compared with photoproduction data from DESY-HERA.
We present a nonperturbative QCD calculation of elastic $J/psi$ meson production in photon-proton scattering at high energies. Using light cone wave functions of the photon and vector mesons, and the framework of the model of the stochastic QCD vacuum, we calculate the differential and integrated elastic cross sections for $gamma p goto J/psi p $ . With an energy dependence following the two-pomeron model we are able to give a consistent description of the integrated cross sections and the differential cross sections at low $|t|$ in the range from 20 GeV up to the highest HERA energies. We discuss different approaches to introduce saturation and find no specific effects up to energies presently available. We also calculate and compare to experiments the cross section for $upsilon$ photoproduction.
Using short distance QCD methods based on the operator product expansion, we calculate the $J/psi$ photoproduction cross section in terms of the gluon distribution function of the nucleon. Comparing the result with data, we show that experimental behaviour of the cross section correctly reflects the $x$-dependence of the gluon distribution obtained from deep inelastic scattering.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
