Fermions are subject to the Pauli Exclusion Principle (PEP), which is grounded on the spin-statistics theorem and, hence, related to the very same structure of the underlying symmetries. The VIP-2 (VIolation of Pauli exclusion principle - 2) experiment has been performing extreme sensitivity tests of the PEP, up to its current and final configuration, exploiting several experimental setups designed to study different theoretical models of PEP violation, looking for a faint signal of physics Beyond the Standard Model.A current is introduced in the copper target to bring new electrons into the system and, hence, fulfill the requirements of the Messiah-Greenberg Super-Selection rule. The searched spin-statistics violating signal corresponds to X-rays emitted when the new electrons perform atomic transitions to the already filled fundamental level of copper. This work analyzes the set of the VIP-2 data corresponding to a test run of 68 days in a current modulated regime alternating no current with current data-taking in short periods (50 s each), instead the usual alternating months-long data-taking of each of these two phases. We propose an analysis method to improve the experiment’s sensitivity: a spectral analysis constraint with the Discrete Fourier Transformation of the data. Compared to the spectrum-only analysis, about a factor of 1.5 of improvement to the limit for the probability of PEP violation for electrons was obtained.

Italy

Poland

Alessio Porcelli

Massimiliano Bazzi

Nicola Bortolotti

Romania

Mario Bragadireanu

Austria

Michael Cargnelli

Alberto Clozza

Luca Paolis

Germany

Raffaele Grande

Carlo Guaraldo

Mihail Iliescu

Matthias Laubenstein

Simone Manti

Johann Marton

Marco Miliucci

Fabrizio Napolitano

Kristian Piscicchia

Alessandro Scordo

Francesco Sgaramella

Diana Sirghi

Florin Sirghi

Oton Doce

Johann Zmeskal

Catalina Curceanu

VIP-2 with modulated current: pathfinder for enhanced Pauli exclusion principle violation studies

We study spontaneous radiation emission from matter, as predicted by the Continuous Spontaneous Localization (CSL) collapse model. We show that, in an appropriate range of energies of the emitted radiation, the largest contribution comes from the atomic nuclei. Specifically, we show that in the energy range  $$E\sim 10\,-\,10^{5}$$  <math> <mrow> <mi>E</mi> <mo>∼</mo> <mn>10</mn> <mspace width="0.166667em"></mspace> <mo>-</mo> <mspace width="0.166667em"></mspace> <msup> <mn>10</mn> <mn>5</mn> </msup> </mrow> </math>   keV the contribution to the radiation emission from the atomic nuclei grows quadratically with the atomic number of the atom, overtaking the contribution from the electrons, which grows only linearly. This theoretical prediction is then compared with the data from a dedicated experiment performed at the extremely low background environment of the Gran Sasso underground National Laboratory, where the radiation emitted form a sample of Germanium was measured.As a result, we obtain the strongest bounds on the CSL parameters for  $$r_C\le 10^{-6}$$  <math> <mrow> <msub> <mi>r</mi> <mi>C</mi> </msub> <mo>≤</mo> <msup> <mn>10</mn> <mrow> <mo>-</mo> <mn>6</mn> </mrow> </msup> </mrow> </math>   m, improving the previous ones by more than an order of magnitude.

Sandro Donadi

Raffaele Del Grande

Angelo Bassi

Novel CSL bounds from the noise-induced radiation emission from atoms

In this paper we report on the results of two analyses of the data taken with a dedicated VIP-Lead experiment at the Gran Sasso National Laboratory of the INFN. We use measurements taken in an environment that is especially well screened from cosmic rays, with a metal target made of “Roman lead” which is characterised by a low level of intrinsic radioactivity. The analyses lead to an improvement, on the upper bounds of the Pauli Exclusion Principle violation for electrons, which is more than one (four) orders of magnitude, when the electron-atom interactions are described in terms of scatterings (or close encounters) respectively.

Edoardo Milotti

Aidin Amirkhani

Sergio Bartalucci

Sergio Bertolucci

Luca De Paolis

Switzerland

Jean-Pierre Egger

Carlo Fiorini

Andreas Pichler

Dorel Pietreanu

Hexi Shi

Laura Sperandio

Oton Vazquez Doce

Search for a remnant violation of the Pauli exclusion principle in a Roman lead target