The AMADEUS collaboration is providing unique experimental information on the low-energy strong interaction between K− and nucleons exploiting the low momentum K− (pK ∼ 127 MeV/c) produced at the ...DAΦNE collider and using the KLOE detector as active target. The absorption of the K− in light nuclei (H, 4He, 9Be and 12C) are investigated and hyperon-pion/hyperon-nucleons, emitted in the final state, are reconstructed. In the present work the results obtained from the study of Λπ−, Ap and At correlated production will be presented.
The kaonic (3)He and (4)He X-rays emitted in the Formula: see text transitions were measured in the SIDDHARTA experiment. The widths of the kaonic (3)He and (4)He 2p states were determined to be ...Formula: see text, and Formula: see text, respectively. Both results are consistent with the theoretical predictions. The width of kaonic (4)He is much smaller than the value of Formula: see text determined by the experiments performed in the 70's and 80's, while the width of kaonic (3)He was determined for the first time.
Kaonic atoms are an extremely efficient tool to investigate the strong interaction at the low energy Frontier, since they provide direct access to the K
−
N interaction at threshold, eliminating the ...necessity for extrapolation, unlike in the case of scattering experiments. During the 1970s and 1980s, extensive studies were performed on kaonic atoms spanning across a broad spectrum of elements in the periodic table, ranging from lithium to uranium. These measurements provided inputs and constraints for the theoretical description of the antikaon-nuclei interaction potential. Nevertheless, the existing data suffer from significant experimental uncertainties, and numerous measurements have been found to be inconsistent with more recent measurements that utilize advanced detector technology. Furthermore, there remain numerous transitions of kaonic atoms that have yet to be measured. For these reasons, a new era of kaonic atoms studies is mandatory. The DAΦNE electron-positron collider at the INFN Laboratory of Frascati (INFN-LNF) stands out as a unique source of low-energy kaons, having been utilized by Collaborations such as DEAR, SIDDHARTA, and AMADEUS for groundbreaking measurements of kaonic atoms and kaon-nuclei interactions. Presently, the SIDDHARTA-2 experiment is installed at DAΦNE, aiming to perform the first-ever measurement of the 2p → 1s x-ray transition in kaonic deuterium, a crucial step towards determining the isospin-dependent antikaon-nucleon scattering lengths. Based on the experience gained with the SIDDHARTA experiment, which performed the most precise measurement of the kaonic hydrogen 2p → 1s x-ray transition, the SIDDHARTA-2 setup is now fully equipped for the challenging kaonic deuterium measurement. In this paper, we present a comprehensive description of the SIDDHARTA-2 setup and of the first kaonic atoms measurements performed during the commissioning phase of the DAΦNE collider. We also outline a proposal for future measurements of kaonic atoms at DAΦNE beyond SIDDHARTA-2, which is intended to stimulate discussions within the broad scientific community performing research, directly or indirectly, related to this field.
The AMADEUS collaboration is performing experimental investigations in the sector of the low energy strangeness hadron physics by taking advantage of the DAΦNE collider, which provides a unique ...source of monochromatic low-momentum kaons and exploiting the KLOE detector as an active target. The
K
−
single and multi-nuclear absorption on H,
4
He,
9
Be and
12
C, both at-rest and in-flight, are studied with the aim to determine the nature of the controversial Λ(1405), the non-resonant hyperon pion formation amplitude below the
K̅N
threshold, the yield and cross sections of
K
−
multi-nucleon absorptions intimately connected to the antikaon multi-nucleon clusters properties and the
K
−
scattering cross sections on light nuclear targets.
These studies have a strong impact on the non-perturbative strangeness QCD with implications ranging from nuclear physics to the equation of state of neutron stars.
In the VIP (VIolation of Pauli exclusion principle) and its follow-up VIP- 2 experiments at the Laboratori Nazionali del Gran Sasso, we test the validity of the Pauli Exclusion Principle, by ...searching for x-rays from copper atomic transitions from a 2p orbit electron to the ground state which is already occupied by two electrons. Such transitions are prohibited by the Pauli Exclusion Principle. The physics run of the VIP-2 experiment started in late 2016 and will collect data for three years. From the first data taking period of two months we have obtained a new limit better than the VIP result from three years of running. In this article we present the published first physics result from the VIP-2 experiment and discuss about the future perspectives.
The AMADEUS collaboration aims to provide precise experimental information on the K− strong interaction with nucleons in the low-energy regime. The step 0 of AMADEUS consists in the re-analysis of ...the data collected with the KLOE detector at the DAΦNE collider during the 2004/2005 data taking campaign. The absorptions of low-momentum K−s in the nuclei contained in the detector and the beam pipe setup (H, 4He, 9Be and 12C) are investigated. Information on the K− single and multi-nucleon interactions are extracted from the study of the Λπ− and p correlated production in the final state.
The L-series X-rays transitions of the kaonic helium-4 exotic atom were measured by SIDDHARTINO, the reduced configuration of the SIDDHARTA-2 experiment, at the DAΦNE collider of INFN-LNF, with ...gaseous 4He targets at densities of 1.90 g/l and 0.82 g/l, corresponding to 1.5% and 0.66%, respectively, of the liquid helium-4 density. The absolute yields for the Lα transition are determined to be 0.15 ±0.03 and 0.12 ±0.03, for the two target densities. The yields for the Lβ and Lγ transitions are presented relatively to that of the Lα transition. These results are compatible with the yields measured by the SIDDHARTA experiment at the densities of 1.65 g/l and 2.15 g/l and contribute to refine the cascade models describing the de-excitation of kaonic atoms as function of density.
The AMADEUS experiment at the DAΦNE collider of LNF-INFN deals with the investigation of the at-rest, or low-momentum, K
−
interactions in light nuclear targets, with the aim to constrain the low ...energy QCD models in the strangeness sector. The 0 step of the experiment consisted in the reanalysis of the 2004/2005 KLOE data, exploiting K
−
absorptions in H,
4
He,
9
Be and
12
C, leading to the first invariant mass spectroscopic study with very low momentum (about 100 MeV) in-flight K
−
captures. With AMADEUS step 1 a dedicated pure Carbon target was implemented in the central region of the KLOE detector, providing a high statistic sample of pure at-rest K
−
nuclear interaction. The first measurement of the non-resonant transition amplitude $\left| {{A_{{K^ - }n \to \Lambda {\pi ^ - }}} \right|$ at $\sqrt s = 33\,MeV$ below the K̄N threshold is presented, in relation with the Λ(1405) properties studies. The analysis procedure adopted in the serarch for K
−
multi-nucleon absorption cross sections and Branching Ratios will be also described.
Kaonic hydrogen atoms provide a unique laboratory to probe the kaon–nucleon strong interaction at the energy threshold, allowing an investigation of the interplay between spontaneous and explicit ...chiral symmetry breaking in low-energy QCD. The SIDDHARTA Collaboration has measured the K-series X rays of kaonic hydrogen atoms at the DAΦNE electron–positron collider of Laboratori Nazionali di Frascati, and has determined the most precise values of the strong-interaction induced shift and width of the 1s atomic energy level. This result provides vital constraints on the theoretical description of the low-energy K¯N interaction.
Large-area silicon drift detectors (SDDs) were used for the first time in the background condition of a collider for precision spectroscopy of the kaonic atom X-rays in the SIDDHARTA experiment for ...the study of the strong interaction in a low-energy regime. The measurements were performed at the
DA
Φ
NE
electron–positron collider (LNF, Italy), using gas targets of hydrogen, deuterium, helium-3, and helium-4. A test measurement using the kaonic
4He X-rays showed an excellent performance of the SDD devices under the beam conditions, and a good background suppression capability using the time correlation between the kaonic atom X-rays and the back-to-back correlated K
+K
− pairs produced by
φ
decays.
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