Statistical Model Predictions for p+p and Pb+Pb Collisions at LHC
I. Kraus, J. Cleymans, H. Oeschler, K. Redlich, S Wheaton
备注：
7 pages, 5 figures, conference contribution to "International school of nuclear physics", Erice, Sicily, 16 - 24 September 2008; Progress in Particle and Nuclear Physics, 2009, in press
Particle production in p+p and central Pb+Pb collisions at LHC is discussed in the context of the statistical thermal model. For heavy-ion collisions, predictions of various particle ratios are presented. The sensitivity of several ratios on the temperature and the baryon chemical potential is studied in detail, and some of them, which are particularly appropriate to determine the chemical freeze-out point experimentally, are indicated. Considering elementary interactions on the other hand, we focus on strangeness production and its possible suppression. Extrapolating the thermal parameters to LHC energy, we present predictions of the statistical model for particle yields in p+p collisions. We quantify the strangeness suppression by the correlation volume parameter and discuss its influence on particle production. We propose observables that can provide deeper insight into the mechanism of strangeness production and suppression at LHC.
The exclusive $Υ$ photoproduction in ultraperipheral proton-nucleus and nucleus-nucleus collisions at LHC energies is being investigated using pQCD framework which constrain the gluon distribution in the proton and nuclei at low $x$. Rapidity distributions of $Υ$ photoproduction with different gluon distribution parameterization and gluon shadowing for nuclear PDFs including photon flux suppression for strong interaction, are being presented at LHC energies. Predictions done for ultraperipheral collisions at $\sqrt s$=$8.16$ TeV in pPb, and at $\sqrt s$=$5.02$ TeV in PbPb collisions which are …
The cross sections for the reaction $γγ\rightarrow 4\ell$ in proton--proton collisions are calculated at the LHC energies. We show that the purely electroweak process $γγ\rightarrow 4\ell$ can be studied at the LHC and can constitute a background to other processes with $4\ell$ or $2\ell$ final states.
We consider the simultaneous production of two heavy-flavoured hadrons - particularly D mesons - at the LHC. We base our calculations on collinearly factorized QCD at next-to-leading order, using the contemporary parton distribution functions and D-meson fragmentation functions. The contributions of double-parton scatterings are included in the approximation of independent partonic interactions. Our framework benchmarks well with the available proton-proton data from the LHCb collaboration giving us confidence to make predictions for proton-lead collisions. Our results indicate that the double…
Rapidity distributions of vector mesons are computed in dipole model proton-lead ultraperipheral collisions(UPCs) at the CERN Larger Hadron Collider(LHC). The dipole model framework is implemented in the calculations of cross sections in the photon-hadron interaction. The bCGC model and Boosted Gaussian wave functions are employed in the scattering amplitude. We obtain predictions of rapidity distributions of $J/ψ$ meson proton-lead ultraperipheral collisions. The predictions give a good descriptions to the experimental data of ALICE. The rapidity distributions of $ϕ$, $ω$ and $ψ(2s)$ mesons i…
An exact analytical solution to the Balitsky-Kovchegov equation is proposed incorporating Mellin transformation with saddle point approximation. The theoretical significance of this solution is its simplicity in form which requires very less number of parameters. Using this solution along with the idea of color glass condensate, a very good description of RHIC and LHC data on differential yield is obtained for d-Au, p-p and p-Pb collisions. Quantitative prediction for the nuclear modification factors for p-Pb, Pb-Pb and Xe-Xe collisions relevant for very recent LHC run 2 is yielded.
We study the enhanced production of $Λ_c$ charmed baryons relative to that of charmed $D^0$ mesons in proton-proton collisions at LHC energies. We simulated collision events with the enhanced color-reconnection model in PYTHIA 8 MC generator and propose measurements based on the comparative use of different event-activity classifiers to identify the source of the charmed-baryon enhancement. We demonstrate that in this enhanced color-reconnection scenario the excess production is primarily linked to the underlying event and not to the production of high-momentum jets.
We present a detailed discussion on the doubly charmed baryon $Ξ_{cc}$ production at the RHIC and LHC via the proton-nucleus ($p$-N) and nucleus-nucleus (N-N) collision modes. The extrinsic charm mechanism via the subprocesses $g+c\to (cc)[n]+\bar{c}$ and $c+c\to (cc)[n]+g$ together with the gluon-gluon fusion mechanism via the subprocess $g+g\to(cc)[n]+\bar{c}+\bar{c}$ have been taken into consideration, where the intermediate diquark is in $[n]=[^1S_0]_{\bf 6}$-state or $[^3S_1]_{\bar{\bf 3}}$-state, respectively. Total and differential cross sections have been discussed under various collis…
Proton-nucleus collisions serve as an important baseline for the understanding and interpretation of the nucleus-nucleus collisions. These collisions have been employed to characterize the cold nuclear matter effects at SPS and RHIC energies for the past several years, as it was thought that Quark-Gluon Plasma (QGP) is not formed in such collisions. However, at the Large Hadron Collider (LHC), there seems a possibility that QGP is formed during proton-lead (p$-$Pb) collisions. In this work, we have derived an expression for gluon induced excitation of $J/ψ$ to $ψ(2S)$, using pNRQCD, and show t…
The charged particle multiplicity distribution in high energy hadronic and nuclear collisions receive contribution from both diffractive and non diffractive processes. It is experimentally challenging to segregate diffractive events from non-diffractive events. The present work aims to separate and extract the charged particle multiplicity distribution of diffractive and non-diffractive events in hadronic collisions at LHC energies. A data driven model using the topic modelling statistical tool, DEMIX, has been used to demonstrate the proof of concept for p p collisions at 7 TeV generated by P…
