M. Cargnelli

A New Measurement of Kaonic Hydrogen X-rays

The KN system at threshold is a sensitive testing ground for low energy QCD, especially for the explicit chiral symmetry breaking. Therefore, we have measured the K-series x rays of kaonic hydrogen atoms at the DANE electron-positron collider of Laboratori Nazionali di Frascati, and have de- termined the most precise values of the strong-interaction energy-level shift and width of the 1s 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 ǫ1s = 283 ± 36(stat) ± 6(syst) eV and 1s = 541± 89(stat) ± 22(syst) eV, respectively. The new values will provide vital constraints on the theoretical description of the low-energy KN interaction.

Quantum explorations: from the waltz of the Pauli exclusion principle to the rock of the spontaneous collapse

The spin–statistics connection, in particular the Pauli exclusion principle (PEP), plays a very important role in our comprehension of matter and nature. Presently, the PEP violation, possible within some theories, generates a lively debate; it has given birth to a few experiments looking for tiny effects. The violation of the Pauli exclusion principle experiment put a very strong limit on the PEP violation probability by electrons, using the method of searching for PEP forbidden atomic transitions in a copper target. In this paper we present this experiment, the obtained results and future plans to upgrade the experimental setup with fast silicon drift detectors. We then present the idea of using an analogous experimental technique to search for x-rays as a signature of the spontaneous collapse of the wave function, predicted by the continuous spontaneous localization theories, and some very encouraging preliminary results.

Kaonic hydrogen X-ray measurement in SIDDHARTA

Abstract 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 1 s atomic energy level. This result provides vital constraints on the theoretical description of the low-energy K ¯ N interaction.

Precision measurement of the 3d → 2p x-ray energy in kaonic 4He

Abstract We have measured the Balmer-series x-rays of kaonic 4 He atoms using novel large-area silicon drift x-ray detectors in order to study the low-energy K ¯ -nucleus strong interaction. The energy of the 3 d → 2 p transition was determined to be 6467 ± 3 ( stat ) ± 2 ( syst ) eV . The resulting strong-interaction energy-level shift is in agreement with theoretical calculations, thus eliminating a long-standing discrepancy between theory and experiment.

New experimental limit on the Pauli exclusion principle violation by electrons

The Pauli Exclusion Principle (PEP) is one of the basic principles of modern physics and, even if there are no compelling reasons to doubt its validity, it is still debated today because an intuitive, elementary explanation is still missing, and because of its unique stand among the basic symmetries of physics. The present paper reports a new limit on the probability that PEP is violated by electrons, in a search for a shifted K

First observation of hyperfine transitions in muonic deuterium atoms via resonant dμd formation at 34 K

_\alpha

First measurement of kaonic helium-3 X-rays

line in copper: the presence of this line in the soft X-ray copper fluorescence would signal a transition to a ground state already occupied by 2 electrons. The obtained value,

Experimental investigation of muon-induced fusion in liquid deuterium

{1/2} \beta^{2} \leq 4.5\times 10^{-28}

Search for the deeply bound K–pp state from the semi-inclusive forward-neutron spectrum in the in-flight K– reaction on helium-3

, improves the existing limit by almost two orders of magnitude.

Measurement of the in-medium K0 inclusive cross section in pi(-) -induced reactions at 1.15 GeV/c.

Abstract We discovered a resonant formation process of the dμd-mesomolecule from the upper F = 3 2 hyperfine state of the μd-atom, while detecting neutrons from muon catalyzed fusion in deuterium gas at 34 K. This new effect enabled us to directly observe transitions between hyperfine states of the μd-atom for the first time and to determine an accurate experimental value for this transition rate.