Recent AMADEUS Studies of Low-Energy K- —Nucleus/Nuclei Interactions

We briefly report the recent results obtained by the AMADEUS collaboration on experimental studies of the K low-energy interactions with light nuclei and outline the future perspectives

Hunting the "impossible atoms" Pauli exclusion principle violation and spontaneous collapse of the wave function at test

The Pauli exclusion principle (PEP) and, more generally, the spin-statistics connection, are at the very basis of our understanding of matter, life and Universe. The PEP spurs, presently, a lively debate on its possible limits, deeply rooted in the very foundations of Quantum Mechanics. It is, therefore, extremely important to test the limits of its validity. The Violation of the PEP (VIP) experiment established the best limit on the probability that PEP is violated by electrons, using the method of searching for PEP forbidden atomic transitions in copper. We describe the experimental method, the obtained results, and plans to go beyond the actual limit by upgrading the experimental apparatus. We discuss the possibility of using a similar experimental technique to search for X-rays as a signature of the spontaneous collapse of the wave function predicted by continuous spontaneous localization (CSL) theories

Recent AMADEUS studies of low-energy K−K^{−} - nucleus/nuclei interactions

We briefly report the recent results obtained by the AMADEUS collaboration on experimental studies of the K- low-energy interactions with light nuclei and outline the future perspectives

The X-ray machine for the examination of quantum mechanics

By performing X-rays measurements in the underground laboratory of Gran Sasso, LNGS-INFN, we test a basic principle of quantum mechanics: the Pauli exclusion principle (PEP). In the future, we aim to use a similar experimental technique to search for X-rays as a signature of the spontaneous collapse of the wave function predicted by continuous spontaneous localization theories. We present the achieved results of the VIP experiment and the future plans to gain two orders of magnitude in testing PEP with the recently VIP2 setup installed at Gran Sasso

Search for heavy neutral lepton production in K+K^+ decays

A search for heavy neutral lepton production in $K^+$ decays using a data sample collected with a minimum bias trigger by the NA62 experiment at CERN in 2015 is reported. Upper limits at the $10^{-7}$ to $10^{-6}$ level are established on the elements of the extended neutrino mixing matrix $|U_{\ell 4}|^2$ ($\ell=e,\mu$) for heavy neutral lepton mass in the range $170-448~{\rm MeV}/c^2$. This improves on the results from previous production searches in $K^+$ decays, setting more stringent limits and extending the mass range.A search for heavy neutral lepton production in K+ decays using a data sample collected with a minimum bias trigger by the NA62 experiment at CERN in 2015 is reported. Upper limits at the 10−7 to 10−6 level are established on the elements of the extended neutrino mixing matrix |Ue4|2 and |Uμ4|2 for heavy neutral lepton mass in the ranges 170–448 MeV/ c2 and 250–373 MeV/ c2 , respectively. This improves on the previous limits from HNL production searches over the whole mass range considered for |Ue4|2 , and above 300 MeV/ c2 for |Uμ4|2

Search for dark photon decays to μ+μ−\mu^+\mu^- at NA62

International audienceThe NA62 experiment at CERN, designed to study the ultra-rare decay $K^+ \to \pi^+\nu\overline{\nu}$, has also collected data in beam-dump mode. In this configuration, dark photons may be produced by protons dumped on an absorber and reach a decay volume beginning 80 m downstream. A search for dark photons decaying in flight to $\mu^+\mu^-$ pairs is reported, based on a sample of $1.4 \times 10^{17}$ protons on dump collected in 2021. No evidence for a dark photon signal is observed. A region of the parameter space is excluded at 90% CL, improving on previous experimental limits for dark photon masses between 215 and 550 MeV$/c^2$