Measurement of heavy-flavour production as a function of multiplicity in pp and p-Pb collisions with ALICE

TL;DR

This paper measures open heavy-flavour meson production as a function of event multiplicity in proton-proton and proton-lead collisions using ALICE, revealing insights into multi-parton interactions and nuclear effects.

Contribution

It provides the first detailed measurement of heavy-flavour yields versus multiplicity in pp and p-Pb collisions, exploring the role of multi-parton interactions and event activity estimators.

Findings

Heavy-flavour yields increase with multiplicity in both systems.

The nuclear modification factor shows dependence on event activity.

Multiple estimators of event activity are used to understand biases.

Abstract

In these proceedings results are presented from the measurement of open heavy-flavour production as a function of charged-particle multiplicity in pp collisions at $\sqrt {s}$ = 7 TeV and p-Pb collisions at $\sqrt {s_{\rm NN}}$=5.02 TeV recorded with the ALICE detector in 2010 and 2013, respectively. $\rm D^{0}$, $\rm D^{+}$ and $\rm D^{*+}$ mesons are reconstructed from their hadronic decay channels in the central rapidity region, and their production yields are measured in various multiplicity and $p_{\rm T}$ intervals. The per-event yields of $\rm D$ mesons in the various multiplicity intervals, normalized to their multiplicity-integrated value, and their evolution with $p_{\rm T}$ are measured for pp and p-Pb collisions to study the contribution of Multi-Parton Interactions (MPIs) to open charm production in the two systems. The nuclear modification factor of $\rm D$ mesons in p-Pb collisions, defined as the ratio of the $\rm D$-meson yields in p-Pb and pp collisions scaled by the average number of binary collisions $< N_{\rm coll}>$, is discussed in terms of its dependence on the event activity. Several experimental estimators of the event activity are used in order to assess the role of kinematic biases.