Investigating the underlying event with identified leading processes

The event-activity differential investigation of particle production reveals the connection between the leading process and the underlying event. It allows for the study of semi-soft vacuum-QCD effects potentially responsible for collectivity in events with higher activity, such as multiple-parton interactions (MPI). Flavor-dependent studies of these mechanisms can help separate color-charge and mass effects in jet production and fragmentation [1]. We conduct an ALICE measurement of the transverse event-activity dependent D0 meson production.

We investigate the connection of flavor-dependent hard hadroproduction to the underlying event in a phenomenological study together with the colleagues at UNAM, using Monte Carlo simulations. A characteristic enhancement of MPI was found at intermediate momenta, that could be identified as gluon-initiated triggers. We also demonstrated that beauty triggers can be used as proxies for quark-initiated processes [2]. We used simulations to interpret heavy-flavor production in the jet and the underlying event region in case of unidentified as well as identified jet triggers, and proposed a method that establishes the connection of higher-order heavy-flavor production to MPI activity [3].

The role of the underlying event in the charm-baryon enhancement in high-energy pp collisions

We study the enhanced production of charmed baryons relative to charmed mesons in proton–proton collisions at LHC energies. Utilizing simulations with color-reconnection beyond leading color approximation, we propose methods based on the comparative use of several event-activity classifiers to identify the source of the charmed-baryon enhancement (Fig. 1). We also conclude that in the scenario under investigation the excess charmed-baryon production is primarily linked to the underlying event activity and not to the production of jets [4].

[1] Gyulai L (ALICE), J. Phys.: Conf. Ser. 1690 (2020) 012165.
[2] R. Vértesi, Gy. Bencédi, A. Misák, A. Ortiz, Eur. Phys. J. A 57 (2021) 10, 301.
[3] Sándor Sz (Advisor: Vértesi R), OTDK thesis, ELTE (2021).
[4] Z. Varga, R. Vértesi, arXiv:2111.00060 [hep-ph] (submitted to J.Phys.G.)