Multiplicity ($N_{\rm ch}$) distributions and transverse momentum ($p_{\rm T}$) spectra of inclusive primary charged particles in the kinematic range of $|\eta| <~ 0.8$ and $0.15 {\rm GeV}/c <~ p_{T} <~ 10 {\rm GeV}/c$ are reported for pp, p-Pb, Xe-Xe and Pb-Pb collisions at centre-of-mass energies per nucleon pair ranging from $\sqrt{s_{\rm NN}} = 2.76$ TeV up to $13$ TeV. A sequential two-dimensional unfolding procedure is used to extract the correlation between the transverse momentum of primary charged particles and the charged-particle multiplicity of the corresponding collision. This correlation sharply characterises important features of the final state of a collision and, therefore, can be used as a stringent test of theoretical models. The multiplicity distributions as well as the mean and standard deviation derived from the $p_{\rm T}$ spectra are compared to state-of-the-art model predictions.
Submitted to: PLB
e-Print: arXiv:2211.15326 | PDF | inSPIRE
CERN-EP-2022-266
Figure group
Figure 1
The \nch dependence of the mean (left panel) and standard deviation (right panel) of the \pt distributions for (particle-composition corrected) Monte Carlo events in \pp, \ppb and \pbpb collisions at $\sqrsn = 5.02\tev$. Results propagated through a full GEANT model of ALICE and corrected with the sequential 2D unfolding (closed circles) procedure described in the text are compared with the generator-level (open squares) distributions and their ratios are shown in the bottom panels. |   |
Figure 2
Top panel: the correlation of primary charged particle \pt spectra with multiplicity per $\nch > 0$ event for \pp collisions at $\sqrt{s} = 5.02\tev$ Bottom panels: the corresponding relative change of \pt (left) and \nch (right) distributions with respect to the inclusive ones. In the left panel, each of the curves represents a single \nch value, ranging from $\nch = 1$ (blue) to $\nch = 55$ (red). In the right panel, the colours represent the \pt intervals used in this analysis from the lowest in blue to the highest one in red. |    |
Figure 3
Probability density of charged-particle multiplicity \nch (left) and the corresponding KNO-scaled distributions (right) for \pp (top), \ppb (middle), and AA (bottom) collisions at different centre-of-mass energies per nucleon pair. Statistical and systematic uncertainties are shown as bars and semi-transparent bands, respectively. |       |
Figure 4
Ratios of the KNO-scaled multiplicity distributions at various centre-of-mass energies per nucleon pair relative to $\sqrs = 13\tev$ for \pp collisions (top panel) and relative to $\sqrsn = 8.16\tev$ and $\sqrsn = 5.02\tev$ for \ppb and \pbpb collisions, respectively (left and right bottom panels). Statistical and systematic uncertainties are shown as bars and semi-transparent bands, respectively. |    |
Figure 5
Mean (left) and standard deviation (right) of the charged-particle transverse momentum spectra as a function of the charged-particle multiplicity for \pp , \ppb, and \pbpb collisions at a centre-of-mass energy per nucleon pair of $\sqrsn = 5.02\tev$. Statistical and systematic uncertainties are shown as bars and semi-transparent bands, respectively. |   |
Figure 6
Mean (left) and standard deviation (right) of the charged-particle transverse momentum spectra as a function of the charged-particle multiplicity for \pp (top), \ppb (middle), and AA (bottom) collisions at different centre-of-mass energies per nucleon pair. Statistical and systematic uncertainties are shown as bars and semi-transparent bands, respectively. |       |
Figure 7
Mean (left) and standard deviation (right) of the charged-particle transverse momentum spectra as a function of the charged-particle multiplicity (top) and relative multiplicity $\nch / \mnch$ (middle, bottom) for \pp , \ppb, \xexe and \pbpb collisions at various centre-of-mass energies per nucleon pair. The bottom panels show both quantities relative to their multiplicity-inclusive value. Statistical and systematic uncertainties are shown as bars and semi-transparent bands, respectively. |       |
Figure 8
Relative standard deviation of the charged-particle transverse momentum spectra as a function of the absolute (left) and relative (right) charged-particle multiplicity for \pp , \ppb, \xexe and \pbpb collisions at various centre-of-mass energies per nucleon pair Statistical and systematic uncertainties are shown as bars and semi-transparent bands, respectively. |   |
Figure 9
Ratio of model predictions to data for \pp collisions at various energies. The upper panels show it for the multiplicity distributions (left) and their KNO-scaling form (right), the bottom panels represent \mpt (left) and \sigmapt (right). The semi-transparent bands indicate the relative systematic uncertainties of the data. |   |