Measurement of the nuclear modification factor of b-jets in 5.02 TeV Pb+Pb collisions with the ATLAS detector
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Date
2023
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Abstract
This paper presents a measurement of b-jet production in Pb+Pb and pp collisions at
$$\sqrt{s_{_\text {NN}}}=5.02$$
s
NN
=
5.02
TeV with the ATLAS detector at the LHC. The measurement uses 260
$$\text {pb}^{-1}$$
pb
-
1
of pp collisions collected in 2017 and 1.4
$$\text {nb}^{-1}$$
nb
-
1
of Pb+Pb collisions collected in 2018. In both collision systems, jets are reconstructed via the anti-
$$k_{t}$$
k
t
algorithm. The b-jets are identified from a sample of jets containing muons from the semileptonic decay of b-quarks using template fits of the muon momentum relative to the jet axis. In pp collisions, b-jets are reconstructed for radius parameters
$$R= 0.2$$
R
=
0.2
and
$$R= 0.4$$
R
=
0.4
, and only
$$R= 0.2$$
R
=
0.2
jets are used in Pb+Pb collisions. For comparison, inclusive
$$R= 0.2$$
R
=
0.2
jets are also measured using 1.7
$$\text {nb}^{-1}$$
nb
-
1
of Pb+Pb collisions collected in 2018 and the same pp collision data as the b-jet measurement. The nuclear modification factor,
$$R_\text {AA}$$
R
AA
, is calculated for both b-jets and inclusive jets with
$$R= 0.2$$
R
=
0.2
over the transverse momentum range of 80–290 GeV. The nuclear modification factor for b-jets decreases from peripheral to central collisions. The ratio of the b-jet
$$R_\text {AA}$$
R
AA
to inclusive jet
$$R_\text {AA}$$
R
AA
is also presented and suggests that the
$$R_\text {AA}$$
R
AA
for b-jets is larger than that for inclusive jets in central Pb+Pb collisions. The measurements are compared with theoretical calculations and suggest a role for mass and colour-charge effects in partonic energy loss in heavy-ion collisions.
Description
Keywords
Citation
The European Physical Journal C. 2023 May 25;83(5):438