Abstract
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.
Highlights
Experimental tests of the spin-statistics connection are complicated by a simple but stringent condition
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
The basic concept is that some of the new electrons injected into the copper strip may form a wrong symmetry state with the electrons in the inner shells of the copper atoms, so that they could be radiatively captured by these atoms and emit anomalous atomic Xrays as they cascade to the fundamental level of non-Paulian atoms
Summary
Experimental tests of the spin-statistics connection are complicated by a simple but stringent condition. 4.1 we estimate the time dependence of the anomalous X-ray emission process, caused by atomic transitions among “wrong” symmetry states performed by electrons in the conduction band of a conductor material target. The view based on electron-atom scattering is useful in the context of electrical conductivity and is appealing to particle physicists who can map well-known concepts onto it, the scatterings of conduction theory are not related with the atoms themselves, but depend on impurities, lattice imperfections and on phonons (see, e.g., [12]) For this reason we have criticised this view and replaced it with a different picture: in Milotti et al [10] we propose to use the closest approaches to atoms instead of scatterings, and we estimate a “time between close encounters” which is considerably shorter, τE ≈ 3.3 × 10−17 s in copper (τE ≈ 2.5 × 10−17 s in lead). The upper bounds obtained in this work represent the best limit ever on the PEP violation probability for electrons, when the symmetry violation is associated to the wrong pairing of electronelectron pairs
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