VIP-2 -High-Sensitivity Tests on the Pauli Exclusion Principle for Electrons

Area of Science:

• Fundamental physics
• Quantum mechanics
• Particle physics

Background:

• The Pauli Exclusion Principle is a cornerstone of quantum mechanics, stating that no two identical fermions can occupy the same quantum state.
• Testing the principle's validity at high precision is crucial for understanding fundamental interactions and searching for new physics.
• The VIP-2 experiment operates in the low-background environment of the Gran Sasso National Laboratory to achieve unprecedented sensitivity.

Purpose of the Study:

• To place stringent constraints on models predicting violations of the Pauli Exclusion Principle.
• Specifically, to test models that adhere to the Messiah-Greenberg superselection rule.
• To search for evidence of forbidden atomic transitions caused by such violations.

Main Methods:

• The VIP-2 Open Systems experiment utilizes a copper conductor carrying a direct current.
• The experiment searches for X-ray emissions from a forbidden L-shell to K-shell atomic transition in copper.
• This transition is sought when the K-shell is already occupied by two electrons, a scenario forbidden by the Pauli Exclusion Principle.

Main Results:

• Analysis of the first three months of data collected in 2018 is presented.
• The experiment has established the most stringent upper bound to date on the probability of Pauli Exclusion Principle violation.
• This bound is specifically for violations consistent with the Messiah-Greenberg superselection rule.

Conclusions:

• The VIP-2 experiment has successfully constrained theories that predict violations of the Pauli Exclusion Principle.
• The results provide strong evidence supporting the validity of the Pauli Exclusion Principle under tested conditions.
• This work advances the search for new physics beyond the Standard Model by probing fundamental quantum mechanical laws.