{"id":823033,"date":"2026-05-26T10:15:18","date_gmt":"2026-05-26T10:15:18","guid":{"rendered":"https:\/\/www.europesays.com\/us\/823033\/"},"modified":"2026-05-26T10:15:18","modified_gmt":"2026-05-26T10:15:18","slug":"cern-physicists-observe-new-exotic-particle","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/us\/823033\/","title":{"rendered":"CERN Physicists Observe New Exotic Particle"},"content":{"rendered":"

Physicists with the ATLAS Collaboration<\/a> at CERN\u2019s Large Hadron Collider (LHC) have observed the Bc*+ meson, an excited version of the Bc+ meson \u2014 both consist of a charm quark and a bottom antiquark.<\/strong><\/p>\n

\"An<\/a><\/p>\n

An artist\u2019s impression of the Bc*+ meson. Image credit: Daniel Dominguez \/ CERN.<\/p>\n

Protons and neutrons \u2014 the building blocks of matter \u2014 belong to a huge class of particles called hadrons. Hadrons are composite particles made of quarks that are bound together by the strong force.<\/p>\n

They are classified into two groups: baryons, which consist of three quarks (like protons and neutrons), and mesons, which are formed by a quark-antiquark pair.<\/p>\n

Despite decades of study, many aspects of the strong force remain poorly understood, particularly the way it binds quarks together inside hadrons.<\/p>\n

Mesons made of heavy quarks \u2014 such as charm or bottom quarks \u2014 can provide an important laboratory for testing theoretical descriptions of these effects.<\/p>\n

Of particular interest to physicists are Bc+ mesons, as they contain two types of heavy quarks: a charm quark and a bottom antiquark.<\/p>\n

The ATLAS physicists produced the excited version of the Bc+ meson in high-energy proton-proton collisions at the LHC.<\/p>\n

According to the team, Bc*+ quickly decays into a Bc+ meson and a photon.<\/p>\n

Detecting this photon along with the decay products of the Bc+ meson would provide the researchers with the \u2018smoking gun\u2019 demonstrating the presence of the Bc*+ meson.<\/p>\n

However, the main challenge is that the expected mass of the Bc+ meson is only slightly larger than that of the Bc+ meson, which means the photon produced in the decay carries very little energy<\/p>\n

In fact, the energy is so low that it cannot be easily detected through the normal approach.<\/p>\n

Rather than using standard photon-identification techniques, the scientists instead looked for the photon converting into an electron-positron pair within the ATLAS tracking detector, leaving behind closely spaced charged-particle tracks originating from a common point displaced from the initial proton-proton collision.<\/p>\n

These tracks can have transverse momenta as low as 100 MeV \u2014 significantly lower than those typically studied in ATLAS analyses.<\/p>\n

This required the authors to deploy a dedicated track-reconstruction procedure to be able to successfully reconstruct the photons and thus identify the Bc*+ meson.<\/p>\n

The measured mass difference between the Bc*+ meson and the Bc+ meson is 64.5 \u00b1 1.4 MeV.<\/p>\n

\u201cThis is within the range of the available theoretical expectations, though slightly deviating from the most recent, high-precision modern calculations,\u201d the physicists said.<\/p>\n

\u201cThis result provides valuable new input for theoretical models describing the masses of particles containing the heavier quarks and will help to improve the understanding of the strong nuclear force.\u201d<\/p>\n

The team\u2019s work<\/a> will be published in the journal Physics Review Letters<\/a>.<\/p>\n

_____<\/p>\n

ATLAS Collaboration. 2026. Observation of a Bc*+ meson with the ATLAS detector. Physics Review Letters, in press; arXiv: 2605.16228<\/p>\n","protected":false},"excerpt":{"rendered":"Physicists with the ATLAS Collaboration at CERN\u2019s Large Hadron Collider (LHC) have observed the Bc*+ meson, an excited…\n","protected":false},"author":3,"featured_media":823034,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[25],"tags":[338251,6753,338252,338253,285838,809,338254,26357,5647,492,285842,267694,159,67,132,68],"class_list":["post-823033","post","type-post","status-publish","format-standard","has-post-thumbnail","category-physics","tag-antiquark","tag-atlas","tag-bc-plus-meson","tag-bottom-antiquark","tag-charm-quark","tag-lhc","tag-meson","tag-particle","tag-photon","tag-physics","tag-proton","tag-quark","tag-science","tag-united-states","tag-unitedstates","tag-us"],"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@us\/116640359590145298","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/823033","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/comments?post=823033"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/823033\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media\/823034"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media?parent=823033"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/categories?post=823033"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/tags?post=823033"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}