Speaker
Description
The strangeness enhancement, defined as the increased relative production of strange hadrons in heavy-ion collisions with respect to the production rate in pp interactions, was originally proposed as a signature of the quark-gluon plasma formation. At the LHC, the ALICE experiment observed that the yield ratios of strange hadrons to charged pions increase with the charged-particle multiplicity at mid-rapidity independently of $\sqrt{s}$ and of the collision systems, starting from pp where it was unexpected, passing by p--Pb and reaching Pb—Pb.
More insightful information about the strangeness production mechanisms could be provided by measuring the (multi-)strange particle multiplicity distribution, P($\textit{n}_{S}$), using a novel method based on counting the number of strange particles event-by-event. In this contribution, ALICE results on $K^{0}_{S}$, $\Lambda$, $\Xi$ and $\Omega$ multiplicity distributions in pp collisions at $\sqrt{s}$ = 5.02 TeV as a function of the charged particle multiplicity, together with the average probability for the production multiplets are presented. This measurement extends the study of strangeness production beyond its average and represents a new test bench for production mechanisms, probing events with a large imbalance between strange and non-strange content.
In addition, a multi-differential approach has been exploited in pp collisions at $\sqrt{s}$ = 13 TeV measuring the production of (multi-)strange hadrons as a function of the very forward energy measured by the ALICE Zero-Degree Calorimeters. This study allows to correlate the production of strangeness with the energy deposited at forward rapidity, that is correlated to the mid-rapidity activity only in the early stages of the collision.
Another multi-differential approach has been utilized to measure the light-flavor particle production as a function of the transverse spherocity ($S_{0}^{p_{T}=1}$) in pp collisions at $\sqrt{s}$ = 13 TeV. This observable allows for a topological selection of events that are either "isotropic" (dominated by multiple soft processes) or "jet-like" (dominated by one or few hard scatterings).
The results are compared to state-of-the-art phenomenological models implemented in commonly-used Monte Carlo event generators, drastically enhancing the sensitivity to the different processes implemented in each approach.
Details
Sara Pucillo
PhD Student
Università & INFN Torino
Italy
| Internet talk | No |
|---|---|
| Is this an abstract from experimental collaboration? | Yes |
| Name of experiment and experimental site | ALICE (https://alice-collaboration.web.cern.ch/) |
| Is the speaker for that presentation defined? | Yes |
