#CMSpaper: Jet peak shapes based on two-particle angular correlations in lead-lead collisions at √(s_NN) = 5.02 TeV (arXiv:2603.14385)
https://arxiv.org/abs/2603.14385 #HeavyIons 
Jet peak shapes based on two-particle angular correlations in lead-lead collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV
The longitudinal invariance of jet-induced peaks in two-particle correlation functions from relativistic lead-lead collisions is experimentally explored. The data were collected at a center-of-mass energy per nucleon pair of 5.02 TeV in 2018 using the CMS detector. The dataset corresponds to an integrated luminosity of 0.607 nb$^{-1}$. Long- and short-range correlations are studied through two-dimensional distributions of the separations in pseudorapidity and azimuth between particles in an event. Jets manifest as a well-defined peak at small angular separations, and the shape of this peak provides insight into jet medium interactions. This Letter examines the evolution of the jet peak shape, focusing on the dependence of its width and longitudinal asymmetry on the transverse momentum, collision centrality, and pseudorapidity of the associated charged particles. The jet-peak distributions of lower transverse momentum particles broaden in both pseudorapidity and azimuth with increasing collision overlap, with the broadening in pseudorapidity being more pronounced. The longitudinal asymmetry of the peaks is also found to increase as the average pseudorapidity increases. These results are compared to proton-proton collision data that were obtained at the same nucleon-nucleon collision center-of-mass energy with an integrated luminosity of 252 nb$^{-1}$.
#CMSpaper soon on arXiv: Jet peak shapes based on two-particle angular correlations in lead-lead collisions at √(s_NN) = 5.02 TeV (CERN-EP-2025-112)
https://cds.cern.ch/record/2957508 #HeavyIons Jet peak shapes based on two-particle angular correlations in lead-lead collisions at $ \sqrt{{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV
The longitudinal invariance of jet-induced peaks in two-particle correlation functions from relativistic lead-lead collisions is experimentally explored. The data were collected at a center-of-mass energy per nucleon pair of 5.02 TeV in 2018 using the CMS detector. The dataset corresponds to an integrated luminosity of 0.607$ \text{nb}^{-1}$. Long- and short-range correlations are studied through two-dimensional distributions of the separations in pseudorapidity and azimuth between particles in an event. Jets manifest as a well-defined peak at small angular separations, and the shape of this peak provides insight into jet medium interactions. This Letter examines the evolution of the jet peak shape, focusing on the dependence of its width and longitudinal asymmetry on the transverse momentum, collision centrality, and pseudorapidity of the associated charged particles. The jet-peak distributions of lower transverse momentum particles broaden in both pseudorapidity and azimuth with increasing collision overlap, with the broadening in pseudorapidity being more pronounced. The longitudinal asymmetry of the peaks is also found to increase as the average pseudorapidity increases. These results are compared to proton-proton collision data that were obtained at the same nucleon-nucleon collision center-of-mass energy with an integrated luminosity of 252$ \text{nb}^{-1}$.
#CMSPAS: Spin-dependent azimuthal asymmetry of coherent J/ψ photoproduction in peripheral PbPb collisions at √(s_NN) = 5.36 TeV (CMS-PAS-HIN-25-006)
https://cds.cern.ch/record/2957192 #HeavyIons #CMSpaper: Observation of the jet diffusion wake using dijets in heavy ion collisions (arXiv:2602.19431)
https://arxiv.org/abs/2602.19431 #HeavyIons #CMSpaper: Observation of the jet diffusion wake using dijets in heavy ion collisions (CMS-HIN-25-012)
https://cds.cern.ch/record/2955422 #HeavyIons Observation of the jet diffusion wake using dijets in heavy ion collisions
Energetic quarks and gluons traversing a hot and dense quark-gluon plasma deposit energy and momentum into the medium before hadronizing to collimated sprays of particles, known as jets. This energy-momentum deposition is expected to produce medium responses, collectively known as jet wakes, with ``diffusion wake'' denoting a depletion of particles in the direction opposite to the propagating jet. These phenomena are studied by comparing dijet-hadron correlations measured in lead-lead (PbPb) and proton-proton ($ \text{pp} $) collisions to assess jet-induced modifications of bulk particle production. The analysis uses PbPb and $ \text{pp} $ data recorded at a nucleon-nucleon center-of-mass energy $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV with the CMS detector at the CERN LHC. By exploring how the dijet-hadron correlation distributions differ for various pseudorapidity separations of the two jets in the dijet, the presence of a jet diffusion wake is firmly established. The wake has a significance greater than 5 standard deviations for charged particles in the transverse momentum range 1 $ < p_{\mathrm{T}} < $ 2 GeV. The measurements are compared with various model predictions with and without jet wake effects, providing new insights into quark-gluon plasma properties and the formation of jet-induced wakes.
#CMSpaper: System-size dependence of charged-particle suppression in ultrarelativistic nucleus-nucleus collisions (arXiv:2602.21325)
https://arxiv.org/abs/2602.21325 #HeavyIons #CMSpaper soon on arXiv: System-size dependence of charged-particle suppression in ultrarelativistic nucleus-nucleus collisions (CERN-EP-2026-032)
https://cds.cern.ch/record/2955423 #HeavyIons System-size dependence of charged-particle suppression in ultrarelativistic nucleus-nucleus collisions
High-energy partons lose energy while propagating through the hot, strongly interacting medium produced in ultrarelativistic nucleus-nucleus collisions, leading to a suppression of particle production at high transverse momentum ($ p_{\mathrm{T}} $). The dependence of this energy loss on the size of the colliding nuclear system has yet to be firmly established experimentally. This Letter presents a systematic study of charged-particle suppression across four different nucleus-nucleus collision systems using nuclear modification factors ($ R_{\text{AA}} $) measured by the CMS Collaboration at the CERN LHC. Previous CMS measurements of $ R_{\text{AA}} $ in oxygen-oxygen, xenon-xenon, and lead-lead collisions are recast with identical $ p_{\mathrm{T}} $ intervals and are complemented by the first measurement of the charged-particle $ R_{\text{AA}} $ in neon-neon collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.36 TeV. The neon-neon data correspond to an integrated luminosity of 0.76$ \text{nb}^{-1}$. The $ R_{\text{AA}} $ in all collision systems examined show similar qualitative trends, but have a magnitude which is ordered with the nucleon number $ A $. The $ R_{\text{AA}} $ feature a downward slope at low $ p_{\mathrm{T}} $, a local minimum at around 5-7 GeV, and an upward slope with increasing $ p_{\mathrm{T}} $. The $ R_{\text{AA}} $ are also compared in terms of $ A^{1/3} $, which is proportional to the nuclear radius. Models including only initial-state nuclear effects fail to reproduce the observed trends, whereas energy loss models reproduce the trends in the region $ p_{\mathrm{T}} > $ 9.6 GeV.
#CMSpaper soon on arXiv: Observation of the jet diffusion wake using dijets in heavy ion collisions (CERN-EP-2026-017)
https://cds.cern.ch/record/2955422 #HeavyIons Observation of the jet diffusion wake using dijets in heavy ion collisions
Energetic quarks and gluons traversing a hot and dense quark-gluon plasma deposit energy and momentum into the medium before hadronizing to collimated sprays of particles, known as jets. This energy-momentum deposition is expected to produce medium responses, collectively known as jet wakes, with ``diffusion wake'' denoting a depletion of particles in the direction opposite to the propagating jet. These phenomena are studied by comparing dijet-hadron correlations measured in lead-lead (PbPb) and proton-proton ($ \text{pp} $) collisions to assess jet-induced modifications of bulk particle production. The analysis uses PbPb and $ \text{pp} $ data recorded at a nucleon-nucleon center-of-mass energy $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV with the CMS detector at the CERN LHC. By exploring how the dijet-hadron correlation distributions differ for various pseudorapidity separations of the two jets in the dijet, the presence of a jet diffusion wake is firmly established. The wake has a significance greater than 5 standard deviations for charged particles in the transverse momentum range 1 $ < p_{\mathrm{T}} < $ 2 GeV. The measurements are compared with various model predictions with and without jet wake effects, providing new insights into quark-gluon plasma properties and the formation of jet-induced wakes.
#CMSpaper: First measurement of jet axis decorrelation with photon-tagged jets in pp and PbPb collisions at 5.02 TeV (arXiv:2602.18279)
https://arxiv.org/abs/2602.18279 #HeavyIons #CMSpaper soon on arXiv: First measurement of jet axis decorrelation with photon-tagged jets in pp and PbPb collisions at 5.02 TeV (CERN-EP-2024-331)
https://cds.cern.ch/record/2955158 #HeavyIons First measurement of jet axis decorrelation with photon-tagged jets in pp and $ \mathrm{PbPb} $ collisions at 5.02 TeV
The first measurement of the jet axis decorrelation in events with jets recoiling from an isolated photon is presented for lead-lead ($ \mathrm{PbPb} $) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The jet axis decorrelation is the angular difference ($ \Delta{j} $) between two definitions of the jet axis. This quantity is expected to be sensitive to the scattering of jet constituents in the quark-gluon plasma (QGP). Events which have a leading isolated photon with transverse momentum 60 $ < p_{\mathrm{T}}^{\gamma} < $ 200 GeV and recoiling jets with 30 $ < p_{\mathrm{T}}^{\text{jet}} < $ 100 GeV are selected for the analysis. The $ \mathrm{PbPb} $ result is reported as a function of collision centrality and compared to pp reference data. Jets with $ p_{\mathrm{T}}^{\text{jet}} < $ 60 GeV have consistent $ \Delta{j} $ shapes for pp and $ \mathrm{PbPb} $ collisions. However, a narrowing is observed for jets with $ p_{\mathrm{T}}^{\text{jet}} > $ 60 GeV in central $ \mathrm{PbPb} $ collisions. The results are compared to predictions from the JEWEL, PYQUEN and HYBRID theoretical models, which include different descriptions of parton energy loss in the QGP.
CMS Publications