Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userElucidating the multiplicity dependence of J/$psi$ production in proton-proton collisions with PYTHIA8
120
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
A study of prompt and non-prompt J/$psi$ production as a function of charged-particle multiplicity in inelastic proton--proton (pp) collisions at a centre-of-mass energy of $sqrt{s}$ = 13 TeV based on calculations using the PYTHIA8 Monte Carlo is reported. Recent experimental data shows an intriguing stronger-than-linear increase of the self-normalized J/$psi$ yield with multiplicity; several models, based on initial or final state effects, have been able to describe the observed behaviour. In this paper, the microscopic reasons for this behaviour, like the role of multiple parton interactions, colour reconnections and auto-correlations are investigated. It is observed that the stronger-than-linear increase and the transverse momentum ($p_{rm T}$) dependence, contrary to what is predicted by the other available models, can be attributed to auto-correlation effects only. In absence of auto-correlation effects, the increase of the yield of J/$psi$ with multiplicity -- and in general for all hard processes -- is weaker than linear for multiplicities exceeding about three times the mean multiplicity. The possibility of disentangling auto-correlation effects from other physical phenomena by measuring the charged-particle multiplicity in different pseudo-rapidity and azimuthal regions relative to the J/$psi$ direction is investigated. In this regard, it is suggested to extend the experimental measurements of J/$psi$ production as a function of the charged-particle multiplicity by determining the multiplicity in several azimuthal regions and in particular in the Transverse region with respect to the direction of the J/$psi$ meson.
rate research
Read More
High-multiplicity pp collisions at the Large Hadron Collider (LHC) energies have created special importance in view of the Underlying Event (UE) observables. The recent results of LHC, such as long range angular correlation, flow-like patterns, strangeness enhancement etc. in high multiplicity events are not yet completely understood. In the same direction, the understanding of multiplicity dependence of J/$psi$ production is highly necessary. Transverse spherocity, which is an event shape variable, helps to investigate the particle production by isolating the hard and the soft components. In the present study, we have investigated the multiplicity dependence of J/$psi$ production at mid-rapidity and forward rapidity through the transverse spherocity analysis and tried to understand the role of jets by separating the isotropic and jetty events from the minimum bias collisions. We have analyzed the J/$psi$ production at the mid-rapidity and forward rapidities via dielectron and dimuon channels, respectively using 4C tuned PYTHIA8 event generator. The analysis has been performed in two different center-of-mass energies: $sqrt{s}$ = 5.02 and 13 TeV, to see the energy dependence of jet contribution to the multiplicity dependence study of J/$psi$ production. Furthermore, we have studied the production dynamics through the dependence of thermodynamic parameters on event multiplicity and transverse spherocity.
Measured J/Psi production cross sections for 200 and 450 GeV/c protons incident on a variety of nuclear targets are analyzed within a Glauber framework which takes into account energy loss of the beam proton, the time delay of particle production due to quantum coherence, and absorption of the J/Psi on nucleons. The best representation is obtained for a coherence time of 0.5 fm/c, previously determined by Drell-Yan production in proton-nucleus collisions, and an absorption cross section of 3.6 mb, which is consistent with the value deduced from photoproduction of the J/Psi on nuclear targets.
We study inclusive heavy quarkonium production with definite polarizations in polarized proton-proton collisions using the non-relativistic QCD color-octet mechanism. We present results for rapidity distributions of cross sections and spin asymmetries for the production of J/psi and psi with specific polarizations in polarized p-p collisions at sqrt s = 200 GeV and 500 GeV at the RHIC within the PHENIX detector acceptance range.
We present results for the $p p to p p omega$ reaction studied by considering two different scenarios: with and without the inclusion of nucleon resonance excitations. The recently measured angular distribution by the COSY-TOF Collaboration at an excess energy of $Q = 173$ MeV and the energy dependence of the total cross section data for $pi^- p to omega n$ are used to calibrate the model parameters. The inclusion of nucleon resonances improves the theoretical prediction for the energy dependence of the total cross section in $pp to ppomega$ at excess energies $Q < 31$ MeV. However, it still underestimates the data by about a factor of two, and remains a problem in understanding the reaction mechanism.
We study charmonium production in proton-nucleus ($p$-A) collisions focusing on final-state effects caused by the formation of an expanding medium. Toward this end, we utilize a rate equation approach within a fireball model as previously employed for a wide range of heavy-ion collisions, adapted to the small systems in $p$-A collisions. The initial geometry of the fireball is taken from a Monte-Carlo event generator where initial anisotropies are caused by fluctuations. We calculate the centrality and transverse-momentum dependent nuclear modification factor ($R_{p{rm A}}$) as well as elliptic flow ($v_2$) for both $J/psi$ and $psi(2S)$ and compare them to experimental data from RHIC and the LHC. While the $R_{p{rm A}}$s show an overall fair agreement with most of the data, the large $v_2$ values observed in $p$-Pb collisions at the LHC cannot be accounted for in our approach. While the former finding generally supports the formation of a near thermalized QCD medium in small systems, the discrepancy in the $v_2$ suggests that its large observed values are unlikely to be due to the final-state collectivity of the fireball alone.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
