The ALICE Collaboration reports measurements of the semi-inclusive distribution of charged-particle jets recoiling from a high transverse momentum (high ) charged hadron, in and central Pb-Pb collisions at center-of-mass energy per nucleon–nucleon collision TeV. The large uncorrelated background in central Pb-Pb collisions is corrected using a data-driven statistical approach which enables precise measurement of recoil jet distributions over a broad range in and jet resolution parameter . Recoil jet yields are reported for , 0.4, and 0.5 in the range and , where is the azimuthal angular separation between hadron trigger and recoil jet. The low- reach of the measurement explores unique phase space for studying jet quenching, the interaction of jets with the quark–gluon plasma generated in high-energy nuclear collisions. Comparison of distributions from and central Pb-Pb collisions probes medium-induced jet energy loss and intra-jet broadening, while comparison of their acoplanarity distributions explores in-medium jet scattering and medium response. The measurements are compared to theoretical calculations incorporating jet quenching. ©2024 CERN, for the ALICE Collaboration2024CERN
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This content will become publicly available on November 1, 2026
Dielectron production in central Pb-Pb collisions at sNN=5.02TeV
The first measurement of the pair production at midrapidity and low invariant mass in central Pb-Pb collisions at at the Large Hadron Collider is presented. The yield of pairs is compared with a cocktail of expected hadronic decay contributions in the invariant mass ( ) and pair transverse momentum ( ) ranges and . For the ratio of data to the cocktail of hadronic contributions amounts to and , including or not including medium effects in the estimation of the heavy-flavor background, respectively. It is consistent with predictions from two different models for an additional contribution of thermal pairs from the hadronic and partonic phases. In the intermediate-mass range ( ), the pair transverse impact parameter of the pairs ( , where “DCA” denotes “distance of closest approach”) is used for the first time in Pb-Pb collisions to separate displaced dielectrons from heavy-flavor hadron decays from a possible (thermal) contribution produced at the interaction point. The data are consistent with a suppression of pairs from and an additional prompt component. Finally, the first direct-photon measurement in the 10% most central Pb-Pb collisions at is reported via the study of virtual direct photons in the transverse momentum range . A model including prompt photons, as well as photons from the preequilibrium and fluid-dynamic phases, can reproduce the result, while being at the upper edge of the data uncertainties.
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- Award ID(s):
- 2208883
- PAR ID:
- 10689729
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- https://journals.aps.org
- Date Published:
- Journal Name:
- Physical Review C
- Volume:
- 112
- Issue:
- 5
- ISSN:
- 2469-9985
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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