The VII-th International Conference on the Initial Stages of High-Energy Nuclear Collisions : Initial Stages 2023

Unfolding the effects of final-state interactions and quantum statistics in two-particle angular correlations

Not scheduled

20m

Copenhagen

Poster New theoretical techniques at large and small coupling

Speaker

Malgorzata Anna Janik (Warsaw University of Technology (PL))

Description

Angular correlations of identified particles measured in ultrarelativistic proton-proton (pp) and heavy-ion collisions exhibit a number of features which depend on the collision system and particle type under consideration. Those features are produced by mechanisms, such as (mini)jets, elliptic flow, resonance decays, and conservation laws. In addition, of particular importance are those related to the quantum statistics (QS) and final-state interactions (FSIs).

In this talk, based on our recent work [1], we show how to unfold the QS and FSI contributions in angular correlation functions by employing a Monte Carlo approach and using momentum correlations (femtoscopy), focusing on pp reactions. We validate the proposed method with PYTHIA 8 Monte Carlo simulations of pp collisions at √s=13 TeV coupled to calculations of QS and FSI effects with the Lednický and Lyuboshitz formalism and provide predictions for the unfolded effects. In particular, we show how those effects modify the shape of the angular correlation function with emphasis on pions and protons. Most importantly, specific structures in the near-side region ((Δη,Δφ)≈(0,0)) of the two-baryon angular correlation function, namely a small enhancement in the middle of a depletion for proton-proton pairs in $pp$ collisions at √s = 7 TeV, observed by ALICE [2], and a depletion for $p\bar{p}$ pairs in Au-Au collisions at collision energies from $\sqrt{s_{NN}}=7.7$ GeV to $\sqrt{s_{NN}}=200$ GeV, observed by STAR [3], originating from the strong interaction, are unveiled with the proposed method. Moreover, we provide a review of the available theoretical descriptions of the near-side shape of the angular correlations of two baryons.

[1] Ł. Graczykowski, M. Janik, Phys. Rev. C 104, 054909 (2021)
https://arxiv.org/abs/2108.00678
[2] J. Adam et al. (ALICE Collaboration), Eur. Phys. J. C77 (2017) 56
https://arxiv.org/abs/1612.08975
[3] J. Adam et al. (STAR Collaboration), Phys. Rev. C 101, 014916 (2020)
https://arxiv.org/abs/1906.09204