A search for collective effects inside jets produced in proton-proton collisions is performed via correlation measurements of charged particles using the CMS detector at the CERN LHC. The analysis uses data collected at a center-of-mass energy of √s = 13 TeV, corresponding to an integrated luminosity of 138 fb−1. Jets are reconstructed with the anti-kT algorithm with a distance parameter of 0.8 and are required to have transverse momentum greater than 550 GeV and pseudorapidity |eta_jet|<1.6. Two-particle correlations among the charged particles within the jets are studied as functions of the particles' azimuthal angle and pseudorapidity separations (Δϕ* and Δη*) in a jet coordinate basis, where particles' η*, ϕ* are defined relative to the direction of the jet. The correlation functions are studied in classes of in-jet charged-particle multiplicity up to Njch ≈ 100. Fourier harmonics are extracted from long-range azimuthal correlation functions to characterize azimuthal anisotropy for |Delta eta*|>2. For low-Njch jets, the long-range elliptic anisotropic harmonic, v*2, is observed to decrease with Njch. This trend is well described by Monte Carlo event generators. However, a rising trend for v*2 emerges at Njch>~80, hinting at a possible onset of collective behavior, which is not reproduced by the models tested. This observation yields new insights into the dynamics of jet evolution in the vacuum.

Observation of Enhanced Long-Range Elliptic Anisotropies Inside High-Multiplicity Jets in pp Collisions at sqrt(s)=13 TeV

Tornago, M.;Cappati, A.;Meridiani, P.;Amapane, N.;Argiro, S.;Bellan, R.;Bellora, A.;Costa, M.;Covarelli, R.;Grippo, M.;Kiani, B.;Luongo, F.;Markovic, L.;Mecca, A.;Migliore, E.;Mulargia, R.;Obertino, M.  M.;Pacher, L.;Siviero, F.;Sola, V.;Solano, A.;Tarricone, C.;Umoret, G.;Shchelina, K.;Rumerio, P.;Ravera, F.;Salvatico, R.;Vagnerini, A.;
2024-01-01

Abstract

A search for collective effects inside jets produced in proton-proton collisions is performed via correlation measurements of charged particles using the CMS detector at the CERN LHC. The analysis uses data collected at a center-of-mass energy of √s = 13 TeV, corresponding to an integrated luminosity of 138 fb−1. Jets are reconstructed with the anti-kT algorithm with a distance parameter of 0.8 and are required to have transverse momentum greater than 550 GeV and pseudorapidity |eta_jet|<1.6. Two-particle correlations among the charged particles within the jets are studied as functions of the particles' azimuthal angle and pseudorapidity separations (Δϕ* and Δη*) in a jet coordinate basis, where particles' η*, ϕ* are defined relative to the direction of the jet. The correlation functions are studied in classes of in-jet charged-particle multiplicity up to Njch ≈ 100. Fourier harmonics are extracted from long-range azimuthal correlation functions to characterize azimuthal anisotropy for |Delta eta*|>2. For low-Njch jets, the long-range elliptic anisotropic harmonic, v*2, is observed to decrease with Njch. This trend is well described by Monte Carlo event generators. However, a rising trend for v*2 emerges at Njch>~80, hinting at a possible onset of collective behavior, which is not reproduced by the models tested. This observation yields new insights into the dynamics of jet evolution in the vacuum.
2024
133
14
1
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https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.133.142301
Hayrapetyan, A.; Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, T.; Chatterjee, S.; Damanakis, K.; Dragicevic, M.; Hussain, P. S.; Jeitler, M.;...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/2068921
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