11. March 2024

Spectroscopy highlights from COMPASS and prospects for the new AMBER experiment Spectroscopy highlights from COMPASS and prospects for the new AMBER experiment

Group report at DPG 2024

Author: Henri Pekeler for the COMPASS and AMBER collaboration

DPG 2024
DPG 2024 © Deutsche Physikalische Gesellschaft
Download all images in original size The impression in connection with the service is free, while the image specified author is mentioned.


The COMPASS experiment, located at the M2 beam line at CERN, had a very rich hadron-physics program for the last two decades. Within this talk, we will focus on the data, for diffractive dissociation, i.e. events of the type π− p → X− p or K− p → X− p, providing the world’s largest data sets in various final states.

The data sets are decomposed into individual JPC contributions by partial-wave analyses employing many novel tools developed by COMPASS. The results provide a full picture of light πJ and aJ mesons up to masses of about 2.5 GeV, including candidates for exotic mesons. Highlights include the solution of the long-standing puzzle of the light spin-exotic state with JPC=1−+, the precise determination of resonance parameters of many states, as well as several signals for new states, some not fitting model expectations. We will also present first results for the strange meson sector, including a significant signal for a supernumerous state with JP=0−.

The successor experiment of COMPASS, AMBER, started data taking for its phase 1 in 2023. In phase 2, several new measurements are planned with a high-intensity kaon beam, including precision spectroscopy of KJ and KJ* states, where no new data has been available for more than 20 years. We will present first studies about improvements of the experimental setup.        Supported by BMBF.

Wird geladen