Limits on Pauli Principle Violation by Nucleons

We consider nuclei produced in core collapse supernovae and subjected to a high neutron flux. We show that an accelerator mass spectrometry experiment that searched for traces of anomalous iron isotopes could set limits on the order of 10−20 − 10−25 on (or perhaps discover) Pauli principle violation by neutrons. A similar search for anomalous Co isotopes could set limits in the range 10−13 − 10−18 on Pauli principle violation by protons. We show that existing data on Oxygen can be used to set a limit of about 10−17 in one proposed model of such violation. The Pauli exclusion principle, one of the the fundamental principles on which our basic understanding of the inner workings of systems ranging from atoms and nuclei to solids and liquids all the way to the stars and the universe rests, is clearly valid to a high degree of precision. Two simple examples in the domain of chemistry and physics are the patterns observed in the periodic table and the success of the shell model for nuclei. Until recently, however, there were hardly any quantitative tests of this fundamental principle. The best limit on possible deviation from the Pauli principle before 1987 was from an early experiment of Goldhaber and ScharffGoldhaber [1] in which beta rays from C were allowed to impinge on lead and a search was made for K-shell x-rays. This bound on possible violation of the Pauli principle (characterized by a parameter β in this article and earlier [2]) by electrons was at the level of 3%. In 1968, Fishbach, Kirsten and Schaffer [3] conducted a search for anomalous Be and put an upper limit on the atmospheric density of such elements. Their result could be interpreted [2] to derive an upper limit of β ≤ 2× 10. In 1987-90, several theoretical papers postulated ways to incorporate small deviations from Bose and Fermi statistics into quantum mechanics and field theories [4, 2, 5, 6]. At this time, it was noted [2] that atomic spectroscopy could improve this bound for electrons to the level of 10. Inspired by the theoretical interest in the subject, several dedicated experiments were planned around 1987-88 and have now considerably improved the limits for electrons [7, 8, 9]. These limits are now at the level of 10 10. As far as other particles go, strong limits for protons (though much weaker than for electrons) have been extracted by Plaga [10] from considerations of energy generation in the Sun. We have listed these limits in the first four rows of Table 1. Note that to date no limit has been established for neutrons. There also exist limits on deviations from bose statistics for bosonic systems such