A new measurement of the magnetic anomaly \ud835\udc4e\ud835\udf07\u2261(\ud835\udc54\ud835\udf07\u22122)\/2 of the positive muon has been obtained by the Muon \ud835\udc54 \u22122 Experiment at Fermi National Accelerator Laboratory (FNAL). This result is based on the third and final dataset (years 2020 to 2023) of the experiment, which contains over 2.5 times the total statistics of the previous results.
\nThe precise determination of the magnetic anomaly \ud835\udc4e\ud835\udf07 has long been awaited as it\u2019s a powerful indicator for possible cracks in the Standard Model, a discrepancy between theory and experiment giving access to fundamental \u201cnew physics\u201d.
\nFrom the ratio of the precession frequencies for muons and protons in a storage ring magnetic field, together with precisely known ratios of fundamental constants, the value \ud835\udc4e\ud835\udf07=1\u2009165\u2009920\u2009710\u2062(162)\u00d710\u221212 (139 ppb) was determined for the new dataset, and \ud835\udc4e\ud835\udf07=1\u2009165\u2009920\u2009705\u2062(148)\u00d710\u221212 (127 ppb) when combined with the previous results of the 2021 and 2023 publications. Altogether, these measurements at FNAL have improved the precision on the world average by over a factor of 4 and will remain the most precise determination of \ud835\udc4e\ud835\udf07 for many years to come.
\nThis precise determination of \ud835\udc4e\ud835\udf07 has boosted also the efforts on the extremely complex calculations of the theoretical value of the muon anomaly.
\nThe Muon \ud835\udc54 \u22122 collaboration counts about 176 scientists from 34 institutions in 7 countries. The Italian group, with scientists from INFN, universities, Scuola Normale and CNR, has contributed on both the experiment and the data analysis. On the experimental side, the Italian group has conceived, built and maintained a laser-based gain monitoring system that continuously calibrated the nearly 1300 silicon photomultipliers (SIPM) of the 24 positron detectors for almost 10 years of data taking. This system significantly contributed reducing the systematic error budget. Ino-Pisa researchers C. Ferrari, A. Fioretti and C. Gabbanini were central to the development of this very peculiar laser system.
\nThese latest results were recently published in Phys. Rev. Lett. 135, 101802, as Editor\u2019s suggestion, featured in Physics, and discussed in Physics Research news of the same day. In the picture, PRL\u2019s issue cover showing Muon \ud835\udc54 \u22122 storage ring at FNAL.<\/p>\n
https:\/\/journals.aps.org\/prl\/abstract\/10.1103\/7clf-sm2v<\/a> A new measurement of the magnetic anomaly \ud835\udc4e\ud835\udf07\u2261(\ud835\udc54\ud835\udf07\u22122)\/2 of the positive muon has been obtained by the Muon \ud835\udc54 \u22122 Experiment at Fermi National Accelerator Laboratory [\u2026]<\/span><\/p>\n","protected":false},"author":1,"featured_media":26313,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[187,72],"tags":[],"class_list":["post-26332","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-homepage-it","category-researchfocus-it"],"_links":{"self":[{"href":"https:\/\/www.ino.cnr.it\/index.php?rest_route=\/wp\/v2\/posts\/26332","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ino.cnr.it\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ino.cnr.it\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ino.cnr.it\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ino.cnr.it\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=26332"}],"version-history":[{"count":1,"href":"https:\/\/www.ino.cnr.it\/index.php?rest_route=\/wp\/v2\/posts\/26332\/revisions"}],"predecessor-version":[{"id":26333,"href":"https:\/\/www.ino.cnr.it\/index.php?rest_route=\/wp\/v2\/posts\/26332\/revisions\/26333"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ino.cnr.it\/index.php?rest_route=\/wp\/v2\/media\/26313"}],"wp:attachment":[{"href":"https:\/\/www.ino.cnr.it\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=26332"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ino.cnr.it\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=26332"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ino.cnr.it\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=26332"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\nhttps:\/\/muon-g-2.fnal.gov\/<\/a>
\nhttps:\/\/muon-gm2-theory.illinois.edu\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"