First results from an extended freed-isobar analysis at COMPASS

Understand

One of the goals of the COMPASS experiment is the precision study of light-meson spectroscopy with data for various final states.

• With $46\times10^6$ exclusive events, the process $\pi^- p\to\pi^-\pi^+\pi^- p$ constitutes the flagship channel.
• Based on this data set, the results of an extensive partial-wave analysis (PWA), using a total of 88 partial waves in the model, were published.
• Along with it, results of a first study of the so-called freed-isobar method were shown.