The strong interaction of charged antikaons (K super(-)) with nucleons and nuclei in the low-energy regime is a fascinating topic. The antikaon plays a peculiar role in hadron physics due to the ...strong attraction antikaon-nucleon which is a key question for possible kaonic nuclear bound states. A rather direct experimental access to the antikaon-nucleon scattering lengths is provided by precision X-ray spectroscopy of transitions to low-lying states in light kaonic atoms like kaonic hydrogen and deuterium. After the successful completion of precision measurements on kaonic hydrogen and helium isotopes by SIDDHARTA at DAPhiNE/LNF, new X-ray studies with the focus on kaonic deuterium are in preparation (SIDDHARTA2). In the future with kaonic deuterium data the antikaon-nucleon isospin-dependent scattering lengths can be extracted for the first time. An overview of the experimental results of SIDDHARTA and an outlook to future perspectives in the SIDDHARTA2 experiments in this frontier research field will be given.
Low-energy QCD is still lacking experimental results, fundamental for reaching a good understanding of the strangeness sector. The information provided by the low energy kaon- nucleon/nuclei ...interaction is accessible through the study of kaonic atoms and kaonic nuclear processes. The lightest atomic systems, namely the kaonic hydrogen and the kaonic deuterium, provide the isospin dependent kaon-nucleon scattering lengths by measuring the X-rays emitted during their de-excitation to the 1s level. The most precise kaonic hydrogen measurement to date, together with an exploratory measurement of kaonic deuterium and of upper-level transitions in kaonic helium 3 and kaonic helium 4 were carried out at the DAΦNE collider by the SIDDHARTA collaboration. Presently, a significantly upgraded setup developped by the SIDDHARTA-2 collaboration is ready to perform a precise measurement of kaonic deuterium and, afterwards, of heavier exotic atoms. In parallel, the kaon-nuclei interaction at momenta below 130 MeV/c is studied by the AMADEUS collaboration, using the KLOE detector and a dedicated setup inserted in the central region, near the interaction point. Preliminary results of the study of charged antikaons interacting with nuclei are shown, including an analysis of the controversial Λ(1405).
The AMADEUS experiment has the aim to perform studies of the low energy hadronic interactions of negatively charged kaons with nucleons and nuclei, which are fundamental to solve longstanding open ...questions in the non-perturbative QCD in the strangeness sector. The DAphiNE collider provides a unique source of monochromatic low-momentum kaons, whose nuclear interaction with the materials of the KLOE detector (used as an active target) provide us excellent acceptance and resolution data for K super(-) capture on H, super(4)He, super(9)Be and super(12)C, both at-rest and in-flight. AMADEUS step 0 consisted in the analysis of the 2004-2005 KLOE data. A second step consisted in the implementation in the central region of the KLOE detector of a pure graphite target, providing a high statistic sample of K super(-) super(12)C nuclear captures at rest. For the future, new setups for various dedicated targets are under preparation. The aim of such investigations is to face the major open questions in hadron nuclear physics in the strangeness sector, such as the nature of the E(1405) state and the resonant versus non-resonant yield in nuclear K super(-) capture, the possible existence of kaonic nuclear clusters, strongly related to a quantitative understanding of single versus multi-nucleon K super(-) absorption.
We measured K-series kaonic hydrogen X-rays in the SIDDHARTA experiment performed at the DAPhiNE electron-positron collider of Laboratori Nazionali di Frascati. With a gaseous hydrogen target of ...density 15 rho sub(STP), preliminary values of the absolute yields, defined as the number of atomic X-rays emitted per kaon stopped inside the target, were determined to be (ProQuest: Formulae and/or non-USASCII text omitted) for K sub( alpha ) transition and (ProQuest: Formulae and/or non-USASCII text omitted) for Ktot, the summation of all the emitted K-series transitions.
The X-ray measurements of kaonic atoms play an important role for understanding the low-energy QCD in the strangeness sector. The SIDDHARTA experiment studied the X-ray transitions of 4 light kaonic ...atoms (H, D, super(3)He, and super(4)He) using the DAFNE electron-positron collider at LNF (Italy). Most precise values of the shift and width of the kaonic hydrogen 1s state were determined, which have been now used as fundamental information for the low-energy K super(-)p interaction in theoretical studies. An upper limit of the X-ray yield of kaonic deuterium was derived, important for future K super(-)d experiments. The shifts and widths of the kaonic super(3)He and super(4)He 2p states were obtained, confirming the end of the "kaonic helium puzzle". In this contribution also the plans for new experiments of kaonic deuterium are being presented.
The strong-interaction shifts and widths of kaonic hydrogen, deuterium, super(3)He, and super(4)He were measured in the SIDDHARTA experiment. The most precise values of the shift and width of the ...kaonic hydrogen 1s state were determined to be epsilon sub(1)s = -283 + or - 36(stat) + or - 6(syst) eV and Gamma sub(1)s = 541 + or - 89(stat) + or - 22(syst) eV. The upper limit of the kaonic deuterium K alpha yield was found to be < or = 0.39%. In addition, the shifts and widths of the kaonic super(3)He and super(4)He 2p states were determined to be epsilon sub(2)p( super(3)He) = -2 + or - 2(stat) + or - 4(syst) eV and T sub(2)p( super(3)He) = 6 + or - 6(stat) + or - 7(syst) eV; epsilon sub(2)p( super(4)He) = +5 + or - 3(stat) + or - 4(syst) eV and Gamma sub(2)p( super(4)He) = 14 + or - 8(stat) + or - 5(syst) eV. These values are important for the constraints of the low-energy KN interaction in theoretical approaches.
The AMADEUS experiment deals with the investigation of the low-energy kaon-nuclei hadronic interaction at the DAPhiNE collider at LNF-INFN, fundamental to respond to longstanding open questions in ...the non-perturbative QCD in the strangeness sector. One of the most interesting aspects is to understand how hadron masses and interactions change in the nuclear environment. The antikaon-nucleon potential is investigated searching for signals from possible bound kaonic clusters, which would imply a strongly attractive antikaon-nucleon potential. AMADEUS step 0 consists in the analysis of 2004/2005 KLOE data, exploring K- absorptions in H, super(4)He, super(9)Be and super(12)C present in setup materials. The status of the various preliminary analyses is presented, together with future perspectives.
High-precision experiments have been done to test the Pauli exclusion principle (PEP) for electrons by searching for anomalous K-series X-rays from a Cu target supplied with electric current. With ...the highest sensitivity the VIP (VIolation of Pauli Exclusion Principle) experiment set an upper limit at the level of 10−29 for the probability that an external electron captured by a Cu atom can make the transition from the 2p state to a 1s state already occupied by two electrons. In a follow-up experiment at Gran Sasso, we aim to increase the sensitivity by two orders of magnitude. We show proofs that the proposed improvement factor is realistic based on the results from recent performance tests of the detectors we did at Laboratori Nazionali di Frascati (LNF).
This work presents the SIDDHARTA experimental results on the kaonic hydrogen and helium atoms, reviewing some fundamental aspects of the physics case. After an introduction about the fundamental role ...played by these bound systems and their X-ray transitions measurements in testing the reliability of the Chiral Perturbation Theory as a realisation of Quantum Chromodynamics at low energies, a short review of the light kaonic atoms physics is given. The review, highlighting the experimental challenges, aims to better understand the SIDDHARTA performances to obtain the most precise spectroscopic X-ray measurements of these light kaonic atoms. A description of the SIDDHARTA apparatus is followed by the presentation of the results on kaonic hydrogen and helium, nowadays the most precise available in literature.
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