Measurement of photon–jet transverse momentum correlations in 5.02 TeV Pb + Pb and pp collisions with ATLAS
Jets created in association with a photon can be used as a calibrated probe to study energy loss in the medium created in nuclear collisions. Measurements of the transverse momentum balance between isolated photons and inclusive jets are presented using integrated luminosities of 0.49 nb-1 of Pb+Pb collision data at $$ \sqrt{s_{NN}}$$ = 5:02 TeV and 25 pb-1 of pp collision data at $$ \sqrt{s}$$ = 5:02 TeV recorded with the ATLAS detector at the LHC. Photons with transverse momentum 63.1 < $$p^γ_{T}$$ < 200 GeV and |ηγ|< 2:37 are paired with all jets in the event that have $$p^{jet}_{T}$$ > 31:6 GeV and pseudorapidity |ηjet| < 2:8. The transverse momentum balance given by the jet-to-photon pT ratio, xJγ, is measured for pairs with azimuthal opening angle ΔΦ > 7π/8. Distributions of the per-photon jet yield as a function of xJγ, (1/Nγ)(dN/dxJγ), are corrected for detector effects via a two-dimensional unfolding procedure and reported at the particle level. In pp collisions, the distributions are well described by Monte Carlo event generators. In Pb+Pb collisions, the xJγ distribution is modified from that observed in pp collisions with increasing centrality, consistent with the picture of parton energy loss in the hot nuclear medium. The data are compared with a suite of energy-loss models and calculations.
- Research Organization:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Harvard Univ., Cambridge, MA (United States); Univ. of Colorado, Boulder, CO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- Contributing Organization:
- The ATLAS Collaboration; ATLAS Collaboration
- Grant/Contract Number:
- AC02-76SF00515; AC02-05CH11231; SC0007881; SC0018117
- OSTI ID:
- 1486903
- Alternate ID(s):
- OSTI ID: 1503073; OSTI ID: 1564005; OSTI ID: 1728676; OSTI ID: 1972615
- Journal Information:
- Physics Letters B, Journal Name: Physics Letters B Vol. 789 Journal Issue: C; ISSN 0370-2693
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- Netherlands
- Language:
- English
Web of Science
Measurement of photon–jet transverse momentum correlations in 5.02 TeV Pb + Pb and $pp$ collisions with ATLAS
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text | January 2019 |
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