CMS-PAS-HIN-23-004

CMS-PAS-HIN-23-004
Energy-energy correlators from PbPb and pp collisions at 5.02 TeV
CMS Collaboration
6 August 2024

Abstract: Energy-energy correlators have recently gained prominence as experimental observables that have predicted sensitivities to a multitude of perturbative and non-perturbative quantum chromodynamics phenomena in high-energy collisions. Using data recorded by the CMS detector, energy-energy correlators are measured in lead-lead (PbPb) collisions for the first time. The data are obtained at a nucleon-nucleon center-of-mass energy of 5.02 TeV with an integrated luminosity of 1.70 nb $^{-1}$ . Inclusive jets with transverse momenta between 120 and 200 GeV are reconstructed using an anti- $k_{\mathrm{T}}$ algorithm with $R=$ 0.4. Two-point correlators are constructed by taking a weighted average of the separation of particle pairs ( $\Delta r$ ) within a given jet cone, with the weight based on the product of the momenta of the two particles. Averages are taken over jets within common jet $p_{\mathrm{T}}$ and collision centrality regions. A similar analysis is done for proton-proton (pp) collisions at the same center of mass energy to obtain a vacuum reference. Taking the ratio of PbPb to pp correlators reveals a non-monotonic shape change at intermediate $\Delta r$ and a significant enhancement at large $\Delta r$ .
Links: CDS record (PDF) ; CADI line (restricted) ; These preliminary results are superseded in this paper, Submitted to PLB. The superseded preliminary plots can be found here.

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