8 research outputs found
A New Measurement of Kaonic Hydrogen X rays
The system at threshold is a sensitive testing ground for low
energy QCD, especially for the explicit chiral symmetry breaking. Therefore, we
have measured the -series x rays of kaonic hydrogen atoms at the DANE
electron-positron collider of Laboratori Nazionali di Frascati, and have
determined the most precise values of the strong-interaction energy-level shift
and width of the atomic state. As x-ray detectors, we used large-area
silicon drift detectors having excellent energy and timing resolution, which
were developed especially for the SIDDHARTA experiment. The shift and width
were determined to be eV and
eV, respectively. The new
values will provide vital constraints on the theoretical description of the
low-energy interaction.Comment: 5 figures, submitted to Physics Letters
Measurements of the strong-interaction widths of the kaonic 3He and 4He 2p levels
The kaonic 3He and 4He X-rays emitted in the 3d-2p transitions were measured
in the SIDDHARTA experiment. The widths of the kaonic 3He and 4He 2p states
were determined to be Gamma_2p(3He) = 6 \pm 6 (stat.) \pm 7 (syst.) eV, and
Gamma_2p(4He) = 14 \pm 8 (stat.) \pm 5 (syst.) eV, respectively. Both results
are consistent with the theoretical predictions. The width of kaonic 4He is
much smaller than the value of 55 \pm 34 eV determined by the experiments
performed in the 70's and 80's, while the width of kaonic 3He was determined
for the first time.Comment: Accepted in Phys. Lett.
X-ray spectroscopy of light kaonic atoms - new results and perspectives
The antikaon interaction on nucleons and nuclei in the low-energy regime is neither simple nor well understood.
Rather direct access to this field is provided by x-ray spectroscopy of light kaonic atoms like kaonic hydrogen, deuterium and helium isotopes. A series of precision measurements on kaonic atoms was performed very successfully by the SIDDHARTA Collaboration at the DAΦNE electron-positron collider at LNF-INFN (Frascati, Italy). Consequently, new precision data on the strong interaction observables (i.e. energy shift and broadening of low-lying atomic states) were delivered having an important impact on the theory of low-energy QCD with strangeness. Presently, the follow-up experiment, SIDDHARTA-2, is in preparation, aiming at a determination of the strong interaction observables in kaonic deuterium as the highest priority; other type of measurements (light and heavier kaonic atoms) are as well foreseen. With the kaonic deuterium data the antikaon-nucleon isospin-resolved scattering lengths can be extracted for the first time. An overview of the progress and present status of experimental studies and an outlook to future perspectives in this fascinating research field is given
Strong-interaction shifts and widths of kaonic helium isotopes
The kaonic He-3 and He-4 3d -> 2p transitions in gaseous targets were observed by the SIDDHARTA experiment. The X-ray energies of these transitions were measured with large-area silicon-drift detectors using the timing information of the K+K- pairs produced by the DA Phi NE e(+)e(-) collider. The strong-interaction shifts and widths both of the kaonic He-3 and He-4 2p states were determined, which are much smaller than the results obtained by the previous experiments. The "kaonic helium puzzle" (a discrepancy between theory and experiment) was now resolved