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

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 $\sqrt {s_{\rm NN}}$=5.02TeVrecordedwiththeALICEdetectorin2010and2013,respectively\mathrm{.}$\rm D^{0}$,$\rm D^{+}$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 $p_{\mathrm{T}}$ intervals. The per-event yields of $\mathrm{D}$ mesons in the various multiplicity intervals, normalized to their multiplicity-integrated value, and their evolution with $p_{\mathrm{T}}$ 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 $\mathrm{D}$ mesons in p-Pb collisions, defined as the ratio of the $\mathrm{D}$-meson yields in p-Pb and pp collisions scaled by the average number of binary collisions $<N_{\mathrm{c}\mathrm{o}\mathrm{l}\mathrm{l}}>$, 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.