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The Pauli exclusion principle (PEP) is one of the basic principles of the modern physics. Being at the very basis of our understanding of matter, it spurs, presently, a lively debate on its possible limits, deeply rooted in the very foundations of Quantum Field Theory. Therefore, it is extremely important to test the limits of its validity. Quon theory provides a suitable mathematical framework of possible violation of PEP, where the violation parameter q translates into a probability of violating PEP. Experimentally, setting a bound on PEP violation means confining the violation parameter to a value very close to either 1 (for bosons) or -1 (for fermions). The VIP (VIolation of the Pauli exclusion principle) experiment established a 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, both in terms of the q-parameter from quon theory and as probability of PEP violation, we briefly discuss them and present future plans to go beyond the actual limit by upgrading the experimental technique using vetoed new spectroscopical fast Silicon Drift Detectors. We also mention the possibility of using a similar experimental technique to search for eventual X-rays, generated in the spontaneous collapse models.

The Pauli exclusion principle (PEP) and, more generally, the spin-statistics connection, is at the very basis of our understanding of matter and Nature. The PEP spurs, presently, a lively debate on its possible limits, deeply rooted in the very foundations of Quantum Mechanics and Quantum Field Theory. Therefore, it is extremely important to test the limits of its validity. Quon theory provides a suitable mathematical framework of possible small violation of PEP, where the q violation parameter translates into a probability of violating PEP. Experimentally, setting a bound on PEP violation means confining the q-parameter to a value very close to either 1 (for bosons) or −1 (for fermions). The VIP (VIolation of the Pauli exclusion principle) experiment established a limit on the probability that PEP is violated by electrons, using the very clean method of searching for PEP forbidden atomic transitions in copper. We describe the experimental method, the obtained results, both in terms of the q-parameter and as probability of PEP violation, we briefly discuss the results and present plans to go beyond the actual limit by upgrading the experimental technique using vetoed new spectroscopic fast Silicon Drift Detectors. We discuss as well the possibility of using a similar experimental technique to search for X-rays generated as a signature of the spontaneous collapse of the wave function, predicted by continuous spontaneous localization type theories.

One of the fundamental rules of nature and a pillar in the foundation of quantum theory and thus of modern physics is represented by the Pauli Exclusion Principle. We know that this principle is extremely well fulfilled due to many observations like the order of the elements and the stability of matter. Numerous experiments were performed to search for tiny violation of this rule in various systems. The VIP experiment at Gran Sasso underground laboratory is testing the validity of this principle for electrons with very high precision (order of 10−30). The layout of the present experiment, results obtained so far and new ideas to further increase the precision will be presented.

The J-PARC E15 experiment has the aims to search for the simplest kaonic nuclear bound state, K − pp, by the in-flight 3He(K −,n) reaction. The exclusive measurement is performed by a simultaneous measurement of the missing mass using the knocked out neutron and the invariant mass via the expected decay, K − pp → Λ p → pπ− p. In this paper, an overview of the experiment and current data analysis of the engineering runs performed in February and June 2012 are presented.

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. A new limit on the probability that PEP is violated by electrons, was estabilished by the VIP (VIolation of the Pauli exclusion principle) Collaboration. The obtained value ½β^2

The goal of the DEAR (DAΦNE Exotic Atom Research) experiment is the precision measurement of the Kα line shift and width, due to the strong interaction, in kaonic hydrogen and the first similar measurement in kaonic deuterium. The final aim is a precision determination of the antikaon‐nucleon isospin dependent scattering lengths, in order to obtain the kaon nucleon sigma terms. In the first phase of the experiment, dedicated to the calibration and optimization of the setup, the experiment collected data on gaseous kaonic nitrogen: for the first time a pattern of three transitions (7 → 6 at 4.6 keV, 6 → 5 at 7.6 keV and 5 → 4 at 14 keV) was measured, and the corresponding yields obtained. The kaonic hydrogen measurement followed, in the last months of 2002, for a total integrated luminosity of about 60 pb−1 . Data analyses are in progress, preliminary results being hereby presented, together with those on kaonic nitrogen. Future measurements: kaonic deuterium, kaonic helium and precise determination of the charged kaon mass are planned in the framework of the SIDDHARTA (SIlicon Drift Detector for Hadronic Atoms Research by Timing Application) experiment, which will replace DEAR on DAΦNE.