Experimental Search for a Violation of the Pauli Exclusion Principle for Electrons: the VIP experiment

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 1⁄2β^2 < 4.5 × 10^-28 is an improvement of about two orders of magnitude of the previous existing limit. © 2007 American Institute of Physics