Observation of medium-induced yield enhancement and acoplanarity broadening of low-$p_{\mathrm{T}}$ jets from measurements in pp and central Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

Abstract

The ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum (high $p_{\mathrm{T}}$) hadron trigger in proton$-$proton and central Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. A data-driven statistical method is used to mitigate the large uncorrelated background in central Pb$-$Pb collisions. Recoil jet distributions are reported for jet resolution parameter $R=0.2$, 0.4, and 0.5 in the range $7<p_{\mathrm{T},\mathrm{jet}}<140$ GeV$/c$ and trigger$-$recoil jet azimuthal separation $\pi /2<\Delta \phi <\pi$. The measurements exhibit a marked medium-induced jet yield enhancement at low $p_{\mathrm{T}}$ and at large azimuthal deviation from $\Delta \phi \sim \pi$. The enhancement is characterized by its dependence on $\Delta \phi$, which has a slope that differs from zero by 4.7$\sigma$. Comparisons to model calculations incorporating different formulations of jet quenching are reported. These comparisons indicate that the observed yield enhancement arises from the response of the QGP medium to jet propagation.

17 pages, 3 captioned figures, authors from page 11, published version, figures at http://alice-publications.web.cern.ch/node/9600

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Cited by in corpus (8)

• Properties of the QCD Matter: A Review of Selected Results from the ALICE Experiment
• Measurements of jet quenching using semi-inclusive hadron+jet distributions in pp and central Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV
• Search for quasi-particle scattering in the quark-gluon plasma with jet splittings in pp and Pb$-$Pb collisions at $\sqrt{{\text{s}}_{\mathrm{NN}}}=5.02$ TeV
• Measurement of medium-induced acoplanarity in central Au-Au and pp collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV using direct-photon+jet and ${\pi }^0$+jet correlations
• Phenomenological study of the angle between jet axes in heavy-ion collisions
• An improved linear Boltzmann transport model for hadron and jet suppression in ultrarelativistic heavy-ion collisions
• Emergence of thermal recoil jets in high-energy heavy-ion collisions
• Probing QCD instantons using jet correlation observables in proton-proton collisions at the LHC