CERN Accelerating science

Two-particle correlation for (left) low- and (right) high-event activity in p--Pb collisions at $\sqrt{s_{\rm NN}}=5.02$\,TeV measured with the LHCb detector~\cite{Aaij:2015qcq}. Primary charged particles were selected in a \pt range of 1--2\,GeV/$c$. The near-side peak around $\Delta\eta=\Delta\phi=0$ is truncated in the histograms.

Two-particle correlation for (left) low- and (right) high-event activity in p--Pb collisions at $\sqrt{s_{\rm NN}}=5.02$\,TeV measured with the LHCb detector~\cite{Aaij:2015qcq}. Primary charged particles were selected in a \pt range of 1--2\,GeV/$c$. The near-side peak around $\Delta\eta=\Delta\phi=0$ is truncated in the histograms.

\pt-integrated yield ratios to pions ($\pi^{+}+\pi^{-}$) as a function of $\langle {\rm d}N_{\rm ch}/{\rm d}\eta \rangle$ measured in $|y|<0.5$. The error bars show the statistical uncertainty, whereas the empty and dark-shaded boxes show the total systematic uncertainty and the contribution uncorrelated across multiplicity bins, respectively. The values measured for pp collisions at $\sqrt{s}=7$\,TeV~\cite{Acharya:2018orn} are compared with results obtained in p--Pb~\cite{Abelev:2013haa} and Pb--Pb collisions at the LHC.

Average transverse momentum as a function of event multiplicity in pp collisions at $\sqrt{s}=13$\,TeV~\cite{Acharya:2019mzb}. Results for the spherocity-integrated case (0--100\%), the most jet-like (0--10\%) and isotropic (90--100\%) events are compared with Monte Carlo predictions. Predictions of PYTHIA~8 with and without (null reconnection range, $\rm{rr}=0$) color reconnection, as well as PYTHIA~6 and EPOS~LHC are displayed. Statistical uncertainties (error bars) are negligible compared to systematic uncertainties (shaded area around the data points). Data to model ratios are shown in the bottom panel. The color band around unity represents the systematic uncertainty.

Multiplicity dependence of (left) ${\rm sc}_{2,3}\{4\}$, (middle) ${\rm sc}_{2,4}\{4\}$ and (right) ${\rm ac}_{2}\{3\}$ in (top) $0.3<\pt<3$\,GeV/$c$ and (bottom) $0.5<\pt<5$\,GeV/$c$ obtained for pp collisions (solid circles), p--Pb collisions (open circles) and low-multiplicity Pb--Pb collisions (open squares)~\cite{Aaboud:2018syf}. The error bars and shaded boxes represent the statistical and systematic uncertainties, respectively.

The ratios of four- and two-particle harmonics ($v_2\{4\}/v2{2}$ and $v_3\{4\}/v_3\{2\}$) are shown as a function of event multiplicity for (left) p--Pb collisions at $\sqrt{s_{\rm NN}}=8.16$\,TeV and (right) Pb--Pb collisions at $\sqrt{s_{\rm NN}}=5.02$\,TeV~\cite{Sirunyan:2019pbr}. Error bars and shaded boxes denote statistical and systematic uncertainties, respectively. The dashed curves show a hydrodynamics-motivated initial-state fluctuation calculation for p--Pb collisions at $\sqrt{s_{\rm NN}}=5.02$\,TeV.