New experimental limit on the Pauli exclusion principle violation by electrons

Abstract

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 Letter reports a new limit on the probability that PEP is violated by electrons, in a search for an anomalous Kα 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, \beta^2/2 < 4.5e-28, improves the existing limit by almost two orders of magnitude

New search for processes violating the Pauli exclusion principle in sodium and in iodine

“…In [25,26] searches for non-Paulian single proton emission in NaI(Tl) have provided stringent limits for PEP validity in 23 Na and 127 I. Here an analogous search for nonPaulian proton spontaneous emission with energy above 10 MeV is performed by analyzing the data collected in a devoted running period of 23.7 days, when the data taking was optimized for the very high energy region.…”

“…TheΓ have been calculated for 23 Na and 127 I according to two possible models for the momentum distribution functions of the nucleons in the bound state: (a) a Fermi momentum distribution with k F = 255 MeV/c; (b) "realistic" functions taking into account the correlation effects. In the latter case, the distribution function calculated for 56 Fe has been adopted both for 23 Na and for 127 I, owing to the fact Table 2 Expected values ofΓ for 23 Na and 127 I; the proton energy threshold is E p = 10 MeV.…”

“…In particular, four classes of experiments have been considered so far: (i) searches for PEP-forbidden electronic states [16][17][18][19]; (ii) searches for PEP-forbidden nuclear states [20]; (iii) searches for PEPforbidden electronic transitions [21][22][23][24]; (iv) searches for PEP-forbidden nuclear transitions [25][26][27][28][29].…”

Testing photons’ Bose-Einstein statistics with Compton scattering

“…There are two good reasons for this. First, it is quite easy to conceive of an experiment to test the Pauli Exclusion Principle: one simply tests whether it is genuinely impossible for two electrons to occupy the same quantum state, something that can be determined from atomic spectroscopy [2]. Second, the classical limit of a fermionic field means having a single quantum present, while the classical limit of a bosonic field involves a large number of quanta.…”

A New Spin on Quantum Gravity

“…There are existing bounds on the violation of Fermi statistics, first performed by Ramberg and Snow [11] and more recently by the VIP collaboration [12]:…”