CMS-PAS-HIN-16-005

CMS-PAS-HIN-16-005
Transverse momentum balance of b-jet pairs in pp and PbPb collisions at $\sqrt{s_{NN}} =$ 5.02 TeV
CMS Collaboration
July 2016

Abstract: The transverse momentum imbalance of pairs of b jets in PbPb and pp collisions at a center-of-mass energy of 5.02 TeV per nucleon pair recorded with the CMS detector at the LHC is reported. A growing mean imbalance is observed with increasing collision centrality, as expected from the jet quenching effect. The data are compared to a measurement with non-identified dijets. A similar level of imbalance is observed within the uncertainties.
Links: CDS record (PDF) ; inSPIRE record ; CADI line (restricted) ; These preliminary results are superseded in this paper, JHEP 03 (2018) 181. The superseded preliminary plots can be found here.

Figures & Tables	Summary	Additional Figures	References	CMS Publications

Figures
png pdf	Figure 1: ROC curve.
png pdf	Figure 2-a: $x_{\rm J}$ and $\Delta \phi $ distributions in the leading-subleading analysis before flavor process reweighting.
png pdf	Figure 2-b: $x_{\rm J}$ and $\Delta \phi $ distributions in the leading-subleading analysis before flavor process reweighting.
png pdf	Figure 3-a: $x_{\rm J}$ and $\Delta \phi $ distributions after flavor process reweighting.
png pdf	Figure 3-b: $x_{\rm J}$ and $\Delta \phi $ distributions after flavor process reweighting.
png pdf	Figure 4-a: $\Delta \phi $ correlations.
png pdf	Figure 4-b: $\Delta \phi $ correlations.
png pdf	Figure 5-a: Jet eclipsing correction.
png pdf	Figure 5-b: Jet eclipsing correction.
png pdf	Figure 6-a: $x_{\rm J}$ distributions in pp collisions.
png pdf	Figure 6-b: $x_{\rm J}$ distributions in pp collisions.
png pdf	Figure 7-a: $x_{\rm J}$ distributions in peripheral (30-100%) PbPb collisions.
png pdf	Figure 7-b: $x_{\rm J}$ distributions in peripheral (30-100%) PbPb collisions.
png pdf	Figure 8-a: $x_{\rm J}$ distributions in mid-central (10-30%) PbPb collisions.
png pdf	Figure 8-b: $x_{\rm J}$ distributions in mid-central (10-30%) PbPb collisions.
png pdf	Figure 9-a: $x_{\rm J}$ distributions in central (0-10%) PbPb collisions.
png pdf	Figure 9-b: $x_{\rm J}$ distributions in central (0-10%) PbPb collisions.
png pdf	Figure 10-a: Mean $x_{\rm J}$ for inclusive (a) dijets and b dijets (b) in pp collisions and for different centrality selections of PbPb collisions. Systematic uncertainties are shown as shaded boxes, while statistical uncertainties are shown as verticial lines.
png pdf	Figure 10-b: Mean $x_{\rm J}$ for inclusive (a) dijets and b dijets (b) in pp collisions and for different centrality selections of PbPb collisions. Systematic uncertainties are shown as shaded boxes, while statistical uncertainties are shown as verticial lines.

Tables
png pdf	Table 1: Relative contributions of production process in PYTHIA to jet pair categories.
png pdf	Table 2: Relative contributions of jet pair categories in pp data and PYTHIA.
png pdf	Table 3: Contributions of the production processes in PYTHIA before and after reweighting.
png pdf	Table 4: Absolute systematic uncertainties on $< x_{\rm J}> $ for inclusive dijets.

Summary

The measurement places constraints on the possible mass and flavor dependence of quenching for the kinematic regime currently probed.

Additional Figures
png pdf	Additional Figure 1: Mean ${x_{\rm J}}$ ratio (left) and difference (right) between PbPb and pp for inclusive dijets and b dijets for different centrality selections of PbPb collisions. Systematic uncertainties are shown as shaded boxes, while statistical uncertainties are shown as vertical lines.
png pdf	Additional Figure 1-a: Mean ${x_{\rm J}}$ ratio between PbPb and pp for inclusive dijets and b dijets for different centrality selections of PbPb collisions. Systematic uncertainties are shown as shaded boxes, while statistical uncertainties are shown as vertical lines.
png pdf	Additional Figure 1-b: Mean ${x_{\rm J}}$ difference between PbPb and pp for inclusive dijets and b dijets for different centrality selections of PbPb collisions. Systematic uncertainties are shown as shaded boxes, while statistical uncertainties are shown as vertical lines.
png pdf	Additional Figure 2: Mean ${x_{\rm J}}$ ratio of b dijets to inclusive dijets for pp collisions and different centrality selections of PbPb collisions. Systematic uncertainties are shown as shaded boxes, while statistical uncertainties are shown as vertical lines.

References
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