Speaker
Description
Kaonic atoms are ideally suited candidates to study the low-energy regime of QCD including strangeness, without the need to extrapolate to zero relative energy as for scattering experiments. The theoretical models describing the low-energy antikaon-nucleon interaction show significant differences, and experimental input is crucial to constrain them. The SIDDHARTA-2 experiment, located at the DA$\Phi$NE collider at LNF in Italy, can provide this input via X-ray spectroscopy of light kaonic atoms, in particular by measuring the $2p \rightarrow 1s$ transition in kaonic deuterium. A combination of the results from kaonic hydrogen measured by SIDDHARTA in 2009 and kaonic deuterium will enable the extraction of the isospin-dependent antikaon-nucleon scattering lengths $a_0$ and $a_1$ for the first time, which are vital parameters for constraining the models. By employing newly developed X-ray detectors in the form of Silicon Drift Detectors as well as sophisticated methods for background suppression, SIDDHARTA-2 is equipped to perform the challenging K$^-$d measurement. During its commissioning in 2021, a first successful run with kaonic helium-4 was performed, and the K$^4$He $2p$ level shift $\epsilon_{2p}$ and width $\Gamma_{2p}$ were extracted and found to be $\epsilon_{2p} = (0.2 \pm 2.5_{stat.} \pm 2.0_{syst.})$ eV and $\Gamma_{2p} = (8 \pm 10)$ eV. The experimental apparatus will be presented and the results from the first data taking campaigns will be discussed.
| Scientific topic | Symmetries and Interactions |
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