Predictions have been compiled for the $p+$Pb LHC runs, focusing on production of hard probes in cold nuclear matter. These predictions were first made for the $sqrt{s_{_{NN}}} = 5.02$ TeV $p+$Pb run and were later compared to the available data. A similar set of predictions were published for the 8.16~TeV $p+$Pb run. A selection of the predictions are reviewed here.
Predictions made in Albacete {it et al} prior to the LHC $p+$Pb run at $sqrt{s_{NN}} = 5$ TeV are compared to currently available data. Some predictions shown here have been updated by including the same experimental cuts as the data. Some additional predictions are also presented, especially for quarkonia, that were provided to the experiments before the data were made public but were too late for the original publication are also shown here.
The production of $Upsilon(nS)$ mesons ($n=1,2,3$) in $p$Pb and Pb$p$ collisions at a centre-of-mass energy per nucleon pair $sqrt{s_{NN}}=8.16$ TeV is measured by the LHCb experiment, using a data sample corresponding to an integrated luminosity of 31.8 nb$^{-1}$. The $Upsilon(nS)$ mesons are reconstructed through their decays into two opposite-sign muons. The measurements comprise the differential production cross-sections of the $Upsilon(1S)$ and $Upsilon(2S)$ states, their forward-to-backward ratios and nuclear modification factors, performed as a function of the transverse momentum pt and rapidity in the nucleon-nucleon centre-of-mass frame $y^*$ of the $Upsilon(nS)$ states, in the kinematic range $p_{rm{T}}<25$ GeV/$c$ and $1.5<y^*<4.0$ ($-5.0<y^*<-2.5$) for $p$Pb (Pb$p$) collisions. In addition, production cross-sections for $Upsilon(3S)$ are measured integrated over phase space and the production ratios between all three $Upsilon(nS)$ states are determined. The measurements are compared to theoretical predictions and suppressions for quarkonium in $p$Pb collisions are observed.
The ALICE data on light flavor hadron production obtained in $p-Pb$ collisions at $sqrt{s_{NN}} $ = 5.02 TeV are studied in the thermal model using the canonical approach with exact strangeness conservation. The chemical freeze-out temperature is independent of centrality except for the lowest multiplicity bin, with values close to 160 MeV but consistent with those obtained in $Pb-Pb$ collisions at $sqrt{s_{NN}}$ = 2.76 TeV. The value of the strangeness non-equilibrium factor $gamma_s$ is slowly increasing with multiplicity from 0.9 to 0.96, i.e. it is always very close to full chemical equilibrium.
Predictions for cold nuclear matter effects on charged hadrons, identified light hadrons, quarkonium and heavy flavor hadrons, Drell-Yan dileptons, jets, photons, gauge bosons and top quarks produced in $p+$Pb collisions at $sqrt{s_{_{NN}}} = 8.16$ TeV are compiled and, where possible, compared to each other. Predictions of the normalized ratios of $p+$Pb to $p+p$ cross sections are also presented for most of the observables, providing new insights into the expected role of cold nuclear matter effects. In particular, the role of nuclear parton distribution functions on particle production can now be probed over a wider range of phase space than ever before.
Predictions and comparisons of hadronic flow observables for Pb+Pb collisions at 2.76 A TeV and 5.02 A TeV are presented using a hydrodynamics + hadronic cascade hybrid approach. Initial conditions are generated via a new formulation of the IP-Glasma model and then evolved using relativistic viscous hydrodynamics and finally fed into transport cascade in the hadronic phase. The results of this work show excellent agreement with the recent charged hadron anisotropic flow measurements from the ALICE collaboration of Pb+Pb collisions at 5.02 A TeV. Event-by-event distributions of charged hadron v n , flow event-plane correlations, and flow factorization breaking ratios are compared with existing measurements at 2.76 A TeV, and are predicted at 5.02 A TeV. Further predictions of identified hadron observables (for both light and multi-strange hadrons), such as p T -spectra and anisotropic flow coefficients, are presented.
R. Vogt
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(2019)
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"Review of predictions of hard probes in $p+$Pb collisions at $sqrt{s_{NN}} = 5.02$ and 8.16 TeV and comparison with data"
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Ramona Vogt
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