Production of the $\rho$(770)${^{0}}$ meson in pp and Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV

TL;DR

This study measures the production of the $ ho$(770)${^{0}}$ meson in proton-proton and lead-lead collisions at 2.76 TeV, revealing a centrality-dependent suppression at low transverse momentum likely due to hadronic rescattering.

Contribution

First measurement of $ ho$(770)${^{0}}$ meson production in pp and Pb-Pb collisions at this energy, showing suppression patterns and supporting rescattering effects in the hadronic phase.

Findings

Suppression of $ ho$(770)$^{0}$ yield ratio in central Pb-Pb collisions

Suppression occurs mainly at low transverse momentum ($p_{T}<2$ GeV/$c$)

Results align with EPOS3 model predictions and similar to $K^{*}$(892)$^{0}/K$ ratio measurements.

Abstract

The production of the $\rho$(770)${^{0}}$ meson has been measured at mid-rapidity $(|y|<0.5)$ in pp and centrality differential Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV with the ALICE detector at the Large Hadron Collider. The particles have been reconstructed in the $\rho$(770)$\rightarrow\pi^{+}\pi^{-}$ decay channel in the transverse momentum ($p_{T}$) range $0.5-11$ GeV/$c$. A centrality dependent suppression of the ratio of the integrated yields $2\rho$(770)$^{0}/(\pi^{+}+\pi^{-})$ is observed. The ratio decreases by $\sim40\%$ from pp to central Pb-Pb collisions. A study of the $p_{T}$-differential $2\rho$(770)$^{0}/(\pi^{+}+\pi^{-})$ ratio reveals that the suppression occurs at low transverse momenta, $p_{T}<2$ GeV/$c$. At higher momentum, particle ratios measured in heavy-ion and pp collisions are consistent. The observed suppression is very similar to that previously measured for the $K^{*}$(892)$^{0}/K$ ratio and is consistent with EPOS3 predictions that may imply that rescattering in the hadronic phase is a dominant mechanism for the observed suppression.