Exploring the hadronic phase with momentum and azimuthal distribution of short-lived resonances and understanding the internal structure of exotic resonances with ALICE

TL;DR

This paper investigates short-lived hadronic resonances in heavy-ion collisions to understand the properties of the hadronic phase and explores the internal structure of exotic resonances, using ALICE Run 3 data and comparisons with theoretical models.

Contribution

It provides new measurements of resonance yields, spectra, and flow in Pb-Pb collisions and examines exotic resonances to shed light on their internal structure and QCD non-perturbative regime.

Findings

Resonance yields are affected by rescattering and regeneration.

Comparison with models helps interpret hadronic phase properties.

Measurements suggest complex internal structures for some exotic resonances.

Abstract

Hadronic resonances are crucial probes to understand the various phases of matter created during relativistic heavy-ion collisions. Due to their short lifetimes, the yields of these resonances can be affected by competing rescattering and regeneration mechanisms in the final hadronic phase. Rescattering can alter the momentum of the resonance decay products, limiting their reconstruction through the invariant-mass technique, while pseudo-elastic scattering can regenerate them. Final state observables such as elliptic flow, transverse momentum spectra, and measured yields of resonances could be significantly modified due to the interaction in the hadronic phase. By comparing the yields of longer-lived resonances, such as the $\phi$-meson with shorter-lived ones, such as the K$^*$(892), it is possible to obtain information about the properties and timescales of the hadronic phase. This contribution presents new Run 3 results on production yields, spectra, and flow harmonics for K$^*$(892) and $\phi$(1020) in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.36 TeV obtained by the ALICE Collaboration. The results are compared with state-of-the-art models to interpret the underlying mechanism that can describe the experimental observations. In addition to probe hadronic phase, the study of resonances also offers valuable insights into the non-perturbative regime of Quantum Chromodynamics (QCD). Resonances such as the f$_0$(980) and f$_1$(1285) challenge the traditional quark model. Their structure is yet unknown as they could potentially be tetraquark states or meson-meson molecules. This contribution presents new measurements of exotic resonances such as f$_0$(980), f$_1$(1285), and the glueball candidates to get more insight into their internal structure.