{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,27]],"date-time":"2026-01-27T10:49:16Z","timestamp":1769510956032,"version":"3.49.0"},"reference-count":24,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2022,4,27]],"date-time":"2022-04-27T00:00:00Z","timestamp":1651017600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Institute for Nuclear Physics","award":["P25529-N20"],"award-info":[{"award-number":["P25529-N20"]}]},{"name":"National Institute for Nuclear Physics","award":["62099"],"award-info":[{"award-number":["62099"]}]},{"name":"National Institute for Nuclear Physics","award":["766900"],"award-info":[{"award-number":["766900"]}]},{"name":"National Institute for Nuclear Physics","award":["FQXi-RFP-CPW-2008"],"award-info":[{"award-number":["FQXi-RFP-CPW-2008"]}]},{"name":"National Institute for Nuclear Physics","award":["FQXi-MGB-2011"],"award-info":[{"award-number":["FQXi-MGB-2011"]}]},{"DOI":"10.13039\/100000925","name":"John Templeton Foundation","doi-asserted-by":"publisher","award":["P25529-N20"],"award-info":[{"award-number":["P25529-N20"]}],"id":[{"id":"10.13039\/100000925","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000925","name":"John Templeton Foundation","doi-asserted-by":"publisher","award":["62099"],"award-info":[{"award-number":["62099"]}],"id":[{"id":"10.13039\/100000925","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000925","name":"John Templeton Foundation","doi-asserted-by":"publisher","award":["766900"],"award-info":[{"award-number":["766900"]}],"id":[{"id":"10.13039\/100000925","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000925","name":"John Templeton Foundation","doi-asserted-by":"publisher","award":["FQXi-RFP-CPW-2008"],"award-info":[{"award-number":["FQXi-RFP-CPW-2008"]}],"id":[{"id":"10.13039\/100000925","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000925","name":"John Templeton Foundation","doi-asserted-by":"publisher","award":["FQXi-MGB-2011"],"award-info":[{"award-number":["FQXi-MGB-2011"]}],"id":[{"id":"10.13039\/100000925","id-type":"DOI","asserted-by":"publisher"}]},{"name":"H2020 FET project TEQ","award":["P25529-N20"],"award-info":[{"award-number":["P25529-N20"]}]},{"name":"H2020 FET project TEQ","award":["62099"],"award-info":[{"award-number":["62099"]}]},{"name":"H2020 FET project TEQ","award":["766900"],"award-info":[{"award-number":["766900"]}]},{"name":"H2020 FET project TEQ","award":["FQXi-RFP-CPW-2008"],"award-info":[{"award-number":["FQXi-RFP-CPW-2008"]}]},{"name":"H2020 FET project TEQ","award":["FQXi-MGB-2011"],"award-info":[{"award-number":["FQXi-MGB-2011"]}]},{"name":"Centro Ricerche Enrico Fermi","award":["P25529-N20"],"award-info":[{"award-number":["P25529-N20"]}]},{"name":"Centro Ricerche Enrico Fermi","award":["62099"],"award-info":[{"award-number":["62099"]}]},{"name":"Centro Ricerche Enrico Fermi","award":["766900"],"award-info":[{"award-number":["766900"]}]},{"name":"Centro Ricerche Enrico Fermi","award":["FQXi-RFP-CPW-2008"],"award-info":[{"award-number":["FQXi-RFP-CPW-2008"]}]},{"name":"Centro Ricerche Enrico Fermi","award":["FQXi-MGB-2011"],"award-info":[{"award-number":["FQXi-MGB-2011"]}]},{"name":"Foundational Questions Institute","award":["P25529-N20"],"award-info":[{"award-number":["P25529-N20"]}]},{"name":"Foundational Questions Institute","award":["62099"],"award-info":[{"award-number":["62099"]}]},{"name":"Foundational Questions Institute","award":["766900"],"award-info":[{"award-number":["766900"]}]},{"name":"Foundational Questions Institute","award":["FQXi-RFP-CPW-2008"],"award-info":[{"award-number":["FQXi-RFP-CPW-2008"]}]},{"name":"Foundational Questions Institute","award":["FQXi-MGB-2011"],"award-info":[{"award-number":["FQXi-MGB-2011"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Symmetry"],"abstract":"<jats:p>Violations of the Pauli Exclusion Principle (PEP), albeit small, could be motivated by physics beyond the Standard Model, ranging from violation of Lorentz invariance to extra space dimensions. This scenario can be experimentally constrained through dedicated, state-of-the-art X-ray spectroscopy, searching for a forbidden atomic transition from the L shell to the K shell already occupied by two electrons. The VIP-2 Experiment located at the underground Gran Sasso National Laboratories of INFN (Italy) tests PEP violations by introducing new electrons via a direct current in a copper conductor, measuring the X-ray energies through a silicon drift detector. Bayesian and frequentist analyses of approximately six months of data taken with the fully operational setup is presented, setting the strongest limit to date on the PEP violation shown by the VIP collaboration. The upper bound on PEP violation are placed at 90% CL \u03b22\/2\u22646.8\u00d710\u221242 with the Bayesian approach, and \u03b22\/2\u22647.1\u00d710\u221242 with the frequentist CLs technique.<\/jats:p>","DOI":"10.3390\/sym14050893","type":"journal-article","created":{"date-parts":[[2022,4,27]],"date-time":"2022-04-27T22:20:20Z","timestamp":1651098020000},"page":"893","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Testing the Pauli Exclusion Principle with the VIP-2 Experiment"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8686-5923","authenticated-orcid":false,"given":"Fabrizio","family":"Napolitano","sequence":"first","affiliation":[{"name":"Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare (INFN), Via E. Fermi 54, I-00044 Rome, Italy"}]},{"given":"Sergio","family":"Bartalucci","sequence":"additional","affiliation":[{"name":"Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare (INFN), Via E. Fermi 54, I-00044 Rome, Italy"}]},{"given":"Sergio","family":"Bertolucci","sequence":"additional","affiliation":[{"name":"Dipartimento di Fisica e Astronomia, Universit\u00e0 di Bologna, Via Irnerio 46, I-40126 Bologna, Italy"}]},{"given":"Massimiliano","family":"Bazzi","sequence":"additional","affiliation":[{"name":"Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare (INFN), Via E. Fermi 54, I-00044 Rome, Italy"}]},{"given":"Mario","family":"Bragadireanu","sequence":"additional","affiliation":[{"name":"Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare (INFN), Via E. Fermi 54, I-00044 Rome, Italy"},{"name":"Institutul National Pentru Fizica si Inginerie Nucleara Horia Hulubei (IFIN-HH), Str. Atomistilor No. 407, P.O. Box MG-6, RO-077125 Magurele, Romania"}]},{"given":"Cesidio","family":"Capoccia","sequence":"additional","affiliation":[{"name":"Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare (INFN), Via E. Fermi 54, I-00044 Rome, Italy"}]},{"given":"Michael","family":"Cargnelli","sequence":"additional","affiliation":[{"name":"Stefan-Meyer-Institute for Subatomic Physics, Austrian Academy of Science, Kegelgasse 27, 1030 Vienna, Austria"}]},{"given":"Alberto","family":"Clozza","sequence":"additional","affiliation":[{"name":"Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare (INFN), Via E. Fermi 54, I-00044 Rome, Italy"}]},{"given":"Luca","family":"De Paolis","sequence":"additional","affiliation":[{"name":"Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare (INFN), Via E. 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