Hadron Spectroscopy with COMPASS at CERN

TL;DR

The COMPASS experiment at CERN investigates the light-quark hadron spectrum, searching for hybrids and glueballs, and has observed a spin-exotic state, providing valuable data for understanding QCD phenomena.

Contribution

This paper reports on the COMPASS experiment's recent results, including the observation of a spin-exotic state and extensive data collection for hadron spectroscopy analysis.

Findings

Observation of a spin-exotic $J^{PC} = 1^{-+}$ state

Test of Chiral Perturbation Theory with Coulomb production data

Large data set enabling detailed partial wave analysis

Abstract

The aim of the COMPASS hadron programme is to study the light-quark hadron spectrum, and in particular, to search for evidence of hybrids and glueballs. COMPASS is a fixed-target experiment at the CERN SPS and features a two-stage spectrometer with high momentum resolution, large acceptance, particle identification and calorimetry. A short pilot run in 2004 resulted in the observation of a spin-exotic state with $J^{PC} = 1^{-+}$ consistent with the debated $\pi1(1600)$. In addition, Coulomb production at low momentum transfer data provide a test of Chiral Perturbation Theory. During 2008 and 2009, a world leading data set was collected with hadron beam which is currently being analysed. The large statistics allows for a thorough decomposition of the data into partial waves. The COMPASS hadron data span over a broad range of channels and shed light on several different aspects of QCD.