Partial-Wave Analysis of the $K^0K^-$ Final State

by Mr Julien Beckers (TUM)

Thursday 16 May 2024, 09:30 → 11:00 Europe/Berlin

E18/ENE Seminar Room 3268 (TUM PH)

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 $K^0$ $K^-$, in which only selected resonances, the $a_J$ states with even spin $J$, are expected to 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 $s\bar{s}$ quark content, due to the two strange mesons. However, in two-body spinless final states such as $K^0K^-$, 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 $K^0K^-$ events, we are able to search for new resonances and measure states with high precision. We will present the results of the partial-wave analysis, which shows several clear resonance signals.