Minimum-bias and the underlying event measurements with ALICE at the LHC.

Tripathy S. per la ALICE Collaboration
  Venerdì 16/09   09:00 - 13:30   Aula B - Maria Goeppert-Mayer   I - Fisica nucleare e subnucleare   Presentazione
To understand the similarities between small and large collision systems, one can study minimum-bias and underlying-event (UE) observables in pp, p-Pb and Pb-Pb collisions. In this contribution, we present the results obtained using UE techniques, allowing the measurement of the particle density in different topological regions with respect to the leading trigger particle. The charged-particle multiplicity in the transverse region is used as a multiplicity estimator to study particle production mechanisms. The UE studies are used to search for jet-like modification. In addition, results on very forward energy, measured by the ALICE zero-degree calorimeters, and differential studies of particle production will be presented for pp and p-Pb collisions. In the second part of the contribution, we will introduce the upgraded Run 3 ALICE configuration and the new Monolithic Active Pixel Sensors-based Inner Tracking System, which allows full tracking and vertexing for $|\eta| < 2.5$. The performance of the new detector and the tracking/matching algorithms will be presented for the $\sqrt{s} = 900$ GeV pp pilot-beam data taken in autumn 2021.