Search for Majorana neutrinos exploiting millikelvin cryogenics with CUORE

Abstract

<jats:title>Abstract</jats:title><jats:p>The possibility that neutrinos may be their own antiparticles, unique among the known fundamental particles, arises from the symmetric theory of fermions proposed by Ettore Majorana in 1937<jats:sup>1</jats:sup>. Given the profound consequences of such Majorana neutrinos, among which is a potential explanation for the matter–antimatter asymmetry of the universe via leptogenesis<jats:sup>2</jats:sup>, the Majorana nature of neutrinos commands intense experimental scrutiny globally; one of the primary experimental probes is neutrinoless double beta (0<jats:italic>νββ</jats:italic>) decay. Here we show results from the search for 0<jats:italic>νββ</jats:italic> decay of <jats:sup>130</jats:sup>Te, using the latest advanced cryogenic calorimeters with the CUORE experiment<jats:sup>3</jats:sup>. CUORE, operating just 10 millikelvin above absolute zero, has pushed the state of the art on three frontiers: the sheer mass held at such ultralow temperatures, operational longevity, and the low levels of ionizing radiation emanating from the cryogenic infrastructure. We find no evidence for 0<jats:italic>νββ</jats:italic> decay and set a lower bound of the process half-life as 2.2 × 10<jats:sup>25</jats:sup> years at a 90 per cent credibility interval. We discuss potential applications of the advances made with CUORE to other fields such as direct dark matter, neutrino and nuclear physics searches and large-scale quantum computing, which can benefit from sustained operation of large payloads in a low-radioactivity, ultralow-temperature cryogenic environment.</jats:p>