Measurement of the mass difference and the binding energy of the hypertriton and antihypertriton

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


According to the CPT theorem, which states that the combined operation of charge conjugation, parity transformation and time reversal must be conserved, particles and their antiparticles should have the same mass and lifetime but opposite charge and magnetic moment. Here, we test CPT symmetry in a nucleus containing a strange quark, more specifically in the hypertriton. This hypernucleus is the lightest one yet discovered and consists of a proton, a neutron and a Λ hyperon. With data recorded by the STAR detector1–3 at the Relativistic Heavy Ion Collider, we measure the Λ hyperon binding energy BΛ for the hypertriton, and find that it differs from the widely used value4 and from predictions5–8, where the hypertriton is treated as a weakly bound system. Our results place stringent constraints on the hyperon–nucleon interaction9,10 and have implications for understanding neutron star interiors, where strange matter may be present11. A precise comparison of the masses of the hypertriton and the antihypertriton allows us to test CPT symmetry in a nucleus with strangeness, and we observe no deviation from the expected exact symmetry.

Original languageEnglish
Pages (from-to)409-412
Number of pages4
JournalNature Physics
Issue number4
StatePublished - Apr 1 2020

Bibliographical note

Funding Information:
The STAR Collaboration acknowledges contributions from V. Dexheimer, F. Hildenbrand and H.-W. Hammer. We thank the Relativistic Heavy Ion Collider (RHIC) Operations Group and the RHIC Computing Facility (RCF) at Brookhaven National Laboratory (BNL), the National Energy Research Scientific Computing (NERSC) Center at Lawrence Berkeley National Laboratory and the Open Science Grid Consortium for providing resources and support. This work was supported in part by the Office of Nuclear Physics within the US Department of Energy Office of Science, the US National Science Foundation, the Ministry of Education and Science of the Russian Federation, the National Natural Science Foundation of China, Chinese Academy of Science, the Ministry of Science and Technology of China and the Chinese Ministry of Education, the National Research Foundation of Korea, the Czech Science Foundation and Ministry of Education, Youth and Sports of the Czech Republic, the Hungarian National Research, Development and Innovation Office, the New National Excellency Programme of the Hungarian Ministry of Human Capacities, the Department of Atomic Energy and Department of Science and Technology of the Government of India, the National Science Centre of Poland, the Ministry of Science, Education and Sports of the Republic of Croatia, RosAtom of Russia and the German Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie (BMBF) and the Helmholtz Association.

Publisher Copyright:
© 2020, The Author(s), under exclusive licence to Springer Nature Limited.

ASJC Scopus subject areas

  • Physics and Astronomy (all)


Dive into the research topics of 'Measurement of the mass difference and the binding energy of the hypertriton and antihypertriton'. Together they form a unique fingerprint.

Cite this