{"id":32866,"date":"2025-12-10T23:04:32","date_gmt":"2025-12-10T17:19:32","guid":{"rendered":"https:\/\/www.revoscience.com\/en\/?p=32866"},"modified":"2025-12-10T23:06:36","modified_gmt":"2025-12-10T17:21:36","slug":"alice-solves-mystery-of-light-nuclei-survival","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/alice-solves-mystery-of-light-nuclei-survival\/","title":{"rendered":"ALICE solves mystery of light-nuclei survival"},"content":{"rendered":"\n

Observations of the formation of light-nuclei from high-energy collisions may help in the hunt for dark matter<\/strong><\/em><\/p>\n\n\n\n

\"\"
Illustration of how deuterons can be produced from a high-energy collision at the LHC. A delta particle emerging from the collision decays into a proton and a pion. The proton undergoes nuclear fusion with a neutron to form deuteron (Image: CERN)<\/sup><\/em><\/figcaption><\/figure>\n\n\n\n

Particle collisions at the Large Hadron Collider<\/a> (LHC) can reach temperatures over one hundred thousand times hotter than at the centre of the Sun. <\/p>\n\n\n\n

Yet, somehow, light atomic nuclei and their antimatter<\/a> counterparts emerge from this scorching environment unscathed, even though the bonds holding the nuclei together would normally be expected to break at a much lower temperature. Physicists have puzzled for decades over how this is possible, but now the ALICE<\/a> collaboration has provided experimental evidence of how it happens, with its results published today in Nature<\/em><\/a>.<\/p>\n\n\n\n

Researchers at ALICE studied deuterons (a proton and a neutron bound together) and antideuterons (an antiproton and an antineutron) that were produced in high-energy collisions of protons at the LHC. They found evidence that, <\/strong>rather than emerging directly from the collisions, nearly 90% of the deuterons and antideuterons were created by the nuclear fusion of particles emerging from the collision, with one of their constituent particles coming from the decay of a short-lived particle.<\/p>\n\n\n\n

\u201cThese results represent a milestone for the field,\u201d said Marco van Leeuwen, spokesperson for the ALICE experiment. \u201cThey fill a major gap in our understanding of how nuclei are formed from quarks and gluons and provide essential input for the next generation of theoretical models.\u201d<\/p>\n\n\n\n

These findings not only explain a long-standing puzzle in nuclear physics but could have far-reaching implications for astrophysics and cosmology. Light nuclei and antinuclei are also produced in interactions between cosmic rays<\/a> and the interstellar medium, and theymay be created in processes involving the dark matter<\/a> that pervades the Universe. By building reliable models for the production of light nuclei and antinuclei, physicists can better interpret cosmic-ray data and look for possible dark-matter signals.<\/p>\n\n\n\n

The ALICE observation provides a solid experimental foundation for modelling light-nuclei formation in space. It shows that most of the light nuclei observed are not created in a single thermal burst, but rather through a sequence of decays and fusions that occur as the system cools.<\/p>\n\n\n\n

The ALICE collaboration came to these conclusions by analysing the deuterons produced from high-energy proton collisions recorded during the second run of the LHC. The researchers measured the momenta of deuterons and pions, which are another type of particle formed of a quark\u2013antiquark pair. They found a correlation between the pion and deuteron momenta, indicating that the pion and either the proton or the neutron of the deuteron actually came from the decay of a short-lived particle.<\/p>\n\n\n\n

This short-lived particle, known as the delta resonance, decays in about one trillionth of a trillionth of a second into a pion and a nucleon, i.e. either a proton or a neutron. The nucleon can then fuse with other nearby nucleons to produce light nuclei such as a deuteron. This nuclear fusion happens at a small distance from the main collision point, in a cooler environment, which gives the freshly created nuclei a much better chance of survival. These results were observed for both particles and antiparticles, revealing that the same mechanism governs the formation of deuterons and antideuterons.<\/p>\n\n\n\n

\u201cThe discovery illustrates the unique capabilities of the ALICE experiment to study the strong nuclear force under extreme conditions,\u201d said Alexander Philipp Kalweit, ALICE physics coordinator.<\/p>\n","protected":false},"excerpt":{"rendered":"

Particle collisions at the\u00a0Large Hadron Collider\u00a0(LHC) can reach temperatures over one hundred thousand times hotter than at the centre of the Sun. <\/p>\n","protected":false},"author":2,"featured_media":32868,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[121,17],"tags":[],"class_list":["post-32866","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-physics","category-research"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons.webp",1587,892,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-200x200.webp",200,200,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-675x379.webp",675,379,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-768x432.webp",750,422,true],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-1100x618.webp",750,421,true],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-1536x863.webp",1536,863,true],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons.webp",1587,892,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-1200x800.webp",1200,800,true],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-870x570.webp",870,570,true],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-600x892.webp",600,892,true],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-600x600.webp",600,600,true],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-760x490.webp",760,490,true],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-550x360.webp",550,360,true],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-95x65.webp",95,65,true],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-640x853.webp",640,853,true],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-96x96.webp",96,96,true],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2025\/12\/deuterons-150x84.webp",150,84,true]},"author_info":{"info":["RevoScience"]},"category_info":"Physics<\/a> Research<\/a>","tag_info":"Research","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/32866","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=32866"}],"version-history":[{"count":2,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/32866\/revisions"}],"predecessor-version":[{"id":32870,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/32866\/revisions\/32870"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/32868"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=32866"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=32866"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=32866"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}