Speaker
Description
Angular correlations between heavy quarks provide an important way to study the quark–gluon plasma (QGP) created in high-energy heavy-ion collisions. Current LHC measurements have reported azimuthal correlations of muons from semileptonic heavy-quark decays in 5.02 TeV Pb+Pb and pp collisions, with $p_{T}^{\mu} > 4 GeV $ and $|\eta^{\mu}| < 2.4$.All $\Delta \phi $ distributions show a pronounced peak near $\pi $, consistent with hard-scattering production. The widths of this peak, characterized using Cauchy–Lorentz fits to the $\Delta \phi $ distributions, are found to vary little with Pb+Pb collision centrality and to be similar in pp and Pb+Pb collisions.
In our work, bottom quarks are produced using the PYTHIA event generator and their interaction with the QGP is simulated with the Linear Boltzmann Transport (LBT) model. After hadronization and decay, the resulting muons are analyzed to study the azimuthal angular correlations of muons from the same collision event.We theoretically investigate the $\Delta \phi $ distributions for all muon pairs, same-sign pairs, and opposite-sign pairs under different transverse-momentum selection cuts.
Our results are consistent with the experimental observations under the condition $p_{T}^{\mu} > 4 $ GeV: the fitted widths of the away-side peak near $\Delta \phi \approx \pi $ do not change significantly with Pb+Pb collision centrality and remain comparable between pp and Pb+Pb collisions. However, when the muon transverse-momentum cut is gradually reduced from $p_{T}^{\mu} > 4$ GeV to $p_{T}^{\mu} > 1$ GeV, a clear broadening of the azimuthal correlation distribution is observed. This indicates a stronger decorrelation effect at lower transverse momenta, which may reflect the influence of bottom-quark energy loss and transport in the QGP medium. These findings suggest that the $p_{T}^{\mu}$ selection plays an important role in heavy-flavor angular-correlation measurements and may provide useful guidance for future experimental studies. In future work, we will further investigate the $p_{T}$-cut dependence of muon-pair correlations from the semileptonic decays of lighter charm hadrons, especially D mesons.
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