R=0.4 hadron+jet $\Delta\phi$ distribution for $20 < p_{\mathrm{T,jet}^{ch}} < 30$ GeV/c in 0-10% Pb-Pb collisions and pp collisions at $\sqrt{\it{s}_{NN}} = 5.02$ TeV compared to JETSCAPE and pQCD+NLO + Sudakov broadening calculation

$\Delta_\mathrm{recoil}$ is calculated as:

$\Delta_\mathrm{recoil} = \frac{1}{N^\mathrm{AA}_\mathrm{trig}} \frac{\mathrm{d^3}N^\mathrm{AA}_\mathrm{{jet}}}{\mathrm{d}p^{\mathrm{ch}}_\mathrm{T,jet} \mathrm{d}\Delta\varphi \mathrm{d}\eta_\mathrm{jet}} \bigg|_{p_\mathrm{T,trig} \in \mathrm{TT_{Sig}}} - c_\mathrm{ref} \cdot \frac{1}{N^\mathrm{AA}_\mathrm{trig}} \frac{\mathrm{d^3}N^\mathrm{AA}_\mathrm{{jet}}}{\mathrm{d}p^{\mathrm{ch}}_\mathrm{T,jet} \mathrm{d}\Delta\varphi \mathrm{d}\eta_\mathrm{jet}} \bigg|_{p_\mathrm{T,trig} \in \mathrm{TT_{Ref}}}$

Here $c_\mathrm{ref}$ is a scaling factor to account for conservation of jet density ( $c_\mathrm{ref} = 0.811$ for the R=0.4 analysis), and the trigger track intervals are in this analysis $TT_{Ref}: 5 <  p_\mathrm{T,trig} < 7$ GeV/c and $TT_{Sig}: 20 <  p_\mathrm{T,trig} < 50$ GeV/c. Jets are reconstructed with charged particles with $p_{T,track} > 0.15$ GeV/c, using the anti-$k_T$ algorithm with resolution parameter R=0.4.

The JETSCAPE [1] prediction for pp collisions uses the PP19 tune as described in [2], and the Pb-Pb prediction includes an in-medium parton shower described by the MATTER [3] (high-virtuality regime) and LBT [4] (low-virtuality regime).

The pQCD@NLO + Sudakov broadening prediction is that described in [5]. The pp prediction includes perturbative parton production with Sudakov resummation. The Pb-Pb prediction includes an additional Sudakov factor to account for medium-induced transverse broadening. The predictions for the jet-normalised $\Delta\varphi$ distributions are scaled such that the magnitude of the prediction matches that of $\Delta_\mathrm{recoil}$ at $\Delta\varphi \sim \pi$. The ratio of these predictions in Pb-Pb and pp collisions, shown on the bottom panel, then shows the sensitivity of this variable to the jet quenching parameter $\hat{q}$, and two hypotheses are shown, $<\hat{q}L> = 13 GeV^2$ and $<\hat{q}L> = 26 GeV^2$.

[1] arXiv:1903.07706 [nucl-th]
[2] Phys. Rev. C 102, 054906 (2020), arXiv:1910.05481 [nucl-th]
[3] Phys. Rev. C 88 (2013) 014909, arXiv:1301.5323 [nucl-th]
[4] Phys. Rev. C 91 (2015) 054908, arXiv:1503.03313 [nucl-th]
[5] Phys. Lett. B 773 (2017) 672-676, arXiv:1607.01932 [hep-ph]