Exotic particle searches with STAR at RHIC

TL;DR

This paper reports preliminary results from the STAR experiment at RHIC, observing a narrow peak in invariant mass spectra that could indicate a new exotic pentaquark particle in heavy-ion collisions.

Contribution

First search for exotic pentaquark states in Au+Au collisions at RHIC using the STAR detector, identifying a potential new particle candidate.

Findings

Observed a narrow peak at 1734 MeV in $\Lambda K^0_s$ invariant mass

Peak has a statistical significance between 3 and 6 sigma

Potential candidate for $N^0$ or $\Xi^0$ pentaquark states

Abstract

We present preliminary results of the STAR experiment at RHIC on exotic particle searches in minimum bias Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. We observe a narrow peak at 1734 $\pm$ 0.5 $\pm$ 5 MeV in the $\Lambda K^0_s$ invariant mass with width consistent with the experimental resolution of about 6 MeV within the errors. The statistical significance can be quantified between 3 and 6 $\sigma$ depending on cuts and methods. If this peak corresponds to a real particle state it would be a candidate for the $N^0$ or the $\Xi^0$ I=1/2 pentaquark states.