Year: 2026
Type: preprint
Abstract: The study of the strong interaction among hadrons at low energies remains one of the key challenges in fundamental physics because of its non-perturbative nature, which makes theoretical descriptions strongly dependent on experimental input. Although substantial progress has been made for systems involving up and down quarks, theoretical models in the strangeness sector continue to face limitations due to the lack of experimental data. Kaonic atoms provide a powerful tool to study the low-energy strong interaction with strangeness through the energy shifts and widths induced on their lowest atomic levels. In this context, kaonic deuterium X-ray spectroscopy has long represented one of the major open challenges in hadronic-atom physics because of its extremely low X-ray yield. This measurement is particularly important because it gives access to the poorly constrained $K^-n$ interaction at threshold. Here, we report the first observation of kaonic deuterium X-ray transitions, performed with the SIDDHARTA-2 experiment at the DA$Φ$NE collider. We determine the strong-interaction shift and width of the $1s$ level to be $\varepsilon_{1s}=-810.9\pm24.5\,(\mathrm{stat})\pm2.1\,(\mathrm{syst})\,\mathrm{eV}$ and $Γ_{1s}=812\pm97\,(\mathrm{stat})\pm33\,(\mathrm{syst})\,\mathrm{eV}$, respectively. This measurement constitutes the most precise experimental determination of the $K^-d$ strong interaction at threshold and allows discrimination among competing theoretical models. Combined with the kaonic hydrogen measurement, this result provides the experimental input required to determine the isospin-dependent $K^-N$ scattering lengths, with implications for the description of the nature of the molecular interpretation of the $Λ(1405)$, and neutron-rich matter.
Source: arXiv (Cornell University)
Authors: Bazzi, Massimiliano, Clozza, Francesco, Guaraldo, Carlo, Iliescu, Mihail Antoniu, Scordo, Alessandro, Sgaramella, Francesco, Sirghi, Diana, Sirghi, Florin, Zmeskal, Johann, Abbene, Leonardo, Amsler, Claude, Artibani, Francesco, Borghi, Giacomo, Bosnar, Damir, Bragadireanu, Mario, Buttacavoli, Antonino, Carminati, Marco, Clozza, Alberto, De Paolis, Luca, Del Grande, Raffaele, Dulski, Kamil, Fiorini, Carlo, Friščić, Ivica, Iwasaki, Masa, Khreptak, Aleksander, Manti, Simone, Marton, Johann, Milardi, Catia, Moskal, Pawel, Napolitano, Fabrizio, Ohnishi, Hiroaki, Piscicchia, Kristian, Principato, Fabio, Silarski, Michał, Skurzok, Magdalena, Spallone, Antonio, Toho, Kairo, Tüchler, Marlene, Doce, Oton Vazquez, Widmann, Eberhard, Curceanu, Catalina
Institutions: Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, University of Rome Tor Vergata, Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering, Stefan Meyer Institute for Subatomic Physics, University of Palermo, MBI - Marietta-Blau-Institut für Teilchenphysik, Roma Tre University, Istituto Nazionale di Fisica Nucleare, Sezione di Milano, Politecnico di Milano, University of Zagreb, RIKEN, TU Wien, Jagiellonian University, Centro Ricerche Enrico Fermi, Tohoku University, Research Center for Accelerator and Radioisotope Science, Tohoku University
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: Measurement of kaonic deuterium X-rays, G151277857, G2267136332, G2876658631, G293853507, G3111662533, G3408410167, G3456612494, G3853406841, G3870388325, High-precision digitized spectroscopy in fundamental research in subatomic physics and applications, G408508751, G4121823795, G4961146383, G5200089266, G523954640, G5891039092, Measurement of kaonic deuterium X-ray transitions, G6282225865, G630697907, G6891605106, G6896087862, G7171697364, G7297228001, G7651396250, G770382516, G8017362841, G8898355295
OpenAlex ID: W7202281626