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Study of jet quenching with isolated-photon+jet correlations in PbPb and pp collisions at $\sqrt{s_{_{\mathrm{NN}}}} =$ 5.02 TeV

The collaboration
No Journal Information, 2017

Abstract
Measurements of azimuthal angle and transverse momentum ($p_\mathrm{T}$) correlations of isolated photons and associated jets are reported for pp and PbPb collisions at $\sqrt{s_{_{\mathrm{NN}}}} =$ 5.02 TeV. The data were recorded with the CMS detector at the CERN LHC. For events containing a leading isolated photon with $p_\mathrm{T}^\gamma >$ 40 GeV$/c$ and an associated jet with $p_\mathrm{T}^\text{jet} >$ 30 GeV$/c$, the photon+jet azimuthal correlation and \pt imbalance in PbPb collisions are studied as functions of collision centrality and $p_\mathrm{T}^\gamma$. The results are compared to pp reference data collected at the same collision energy and to predictions from several theoretical models for parton energy loss. No evidence of broadening of the photon+jet azimuthal correlations is observed, while the ratio $p_\mathrm{T}^\text{jet}/p_\mathrm{T}^\gamma$ decreases significantly for PbPb data relative to the pp reference. All models considered agree within uncertainties with the data. The number of associated jets per photon with $p_\mathrm{T}^\gamma >$ 80 GeV$/c$ is observed to be shifted towards lower $p_\mathrm{T}^\text{jet}$ values in central PbPb collisions compared to pp collisions.

• #### Table 1

Data from Table 1

10.17182/hepdata.80815.v1/t1

Jet resolution parameters for pp and PbPb collisions in various centrality bins.

• #### Table 2

Data from Figure 2

10.17182/hepdata.80815.v1/t2

The azimuthal correlation of photons and jets in five $p_{\mathrm{T}}^{\gamma}$ intervals for 0-30% and 30-100% centrality PbPb collisions. The smeared...

• #### Table 3

Data from Figure 3

10.17182/hepdata.80815.v1/t3

Distribution of $x_{\mathrm{j}\gamma} = p_{\mathrm{T}}^{\mathrm{jet}} / p_{\mathrm{T}}^{\gamma}$ in five $p_{\mathrm{T}}^{\gamma}$ intervals for 0-30% and 30-100% centrality PbPb collisions. The smeared...

• #### Table 4

Data from Figure 4

10.17182/hepdata.80815.v1/t4

The $\langle x_{\mathrm{j}\gamma} \rangle$ and $R_{\mathrm{j}\gamma}$, the number of associated jets per photon, in 0-30% and 30-100% centrality PbPb collisions....

• #### Table 5

Data from Figure 5

10.17182/hepdata.80815.v1/t5

The $I_{\mathrm{AA}}^{\mathrm{jet}}$ vs. $p_{\mathrm{T}}^{\mathrm{jet}}$ for 0-30% and 30-100% centrality PbPb collisions. Bins for which there are no data points are...

• #### Table 6

Data from Figure 6

10.17182/hepdata.80815.v1/t6

The centrality dependence of $x_{\mathrm{j}\gamma}$ of photon+jet pairs normalized by the number of photons for PbPb and smeared pp data....

• #### Table 7

Data from Figure 7

10.17182/hepdata.80815.v1/t7

The $\langle x_{\mathrm{j}\gamma} \rangle$ and $R_{\mathrm{j}\gamma}$ as a function of $\langle N_{\mathrm{part}} \rangle$ for $p_{\mathrm{T}}^{\gamma} > 60$ and 80 GeV....