Speaker
Description
The COMPASS experiment is a multi-purpose two-stage spectrometer located at the CERN SPS. One of its main goals is the investigation of the excitation spectrum of light mesons in diffractive reactions. One of the final states produced at COMPASS is $K_S^0 K^-$, in which only selected resonances, the $a_J$ states with even $J$, can appear at COMPASS’ high beam energies. Performing a partial-wave analysis of the COMPASS data allows a very selective study of these states and enables us to probe their intrinsic $s\bar{s}$ content, due to the two strange mesons. However, in two-body final states such as $K^0_S K^-$, one complication arises: mathematical ambiguities in the partial-wave decomposition result in different combinations of amplitude values describing the same intensity distribution.
Using the so-far largest dataset of $K_S^0 K^-$ events, we are able to search for new resonances and measure states with high precision. We will discuss the ambiguity issue and present the results of the partial-wave analysis, which shows several clear resonance signals.
