  In the VIP2 (VIolation of the Pauli Exlusion Principle) experiment at the
Gran Sasso underground laboratory (LNGS) we are searching for possible
violations of standard quantum mechanics predictions. With high precision we
investigate the Pauli Exclusion Principle and the collapse of the wave function
(collapse models). We will present our experimental method of searching for
possible small violations of the Pauli Exclusion Principle for electrons, via
the search for "anomalous" X-ray transitions in copper atoms, produced by "new"
electrons (brought inside a copper bar by circulating current) which could have
the probability to undergo Pauli-forbidden transition to the ground state (1 s
level) already occupied by two electrons. We will describe the concept of the
VIP2 experiment taking data at LNGS presently. The goal of VIP2 is to test the
PEP for electrons with unprecedented accuracy, down to a limit in the
probability that PEP is violated at the level of 10$^{-31}$. We will show
preliminary experimental results obtained at LNGS and discuss implications of a
possible violation.
