Journal Article

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

Edmonds, T, Ahammed, Z, Hu Y, Feng, Y, Moravcova, Z, Xu, Y F, Fedorisin, J, Gopal, K, Nigmatkulov, G, Sichtermann, E P, Kimelman, B, Xu, Q H, Herrmann, N, Geurts, F, Ray, R L, Hamed, A, Jiang, K, Alekseev, I, Seck, F, Tarnowsky, T, Surrow, B, Voloshin, S A, Magdy, N, Fazio, S, Jacobs, W W, Tribble, R E, Xu N, Liang, Y, Okorokov, V A, Kulathunga, Mudiyanselage N, Pluta, J, Zhao, J, Seger, J, Tokarev, M, Kikoła, D P, Przybycien, M, Schweid, B R, Xu H, Federic, P, Hong, Y, Judd, E G, Wen, L, He S, Mioduszewski, S, Westfall, G D, Dedovich, T G, He W, Cherney, M, He X, Thomas, J H, Reed, R, Majka, R, Xu Z, Mohanty, B, Nie, M, Xu Y, Liu, Y, Liu, X, Drachenberg, J L, Bland, L C, Liu, Z, Liu, T, Seto, R, Pinsky, L, Seyboth, P, Liu, P, Mazer, J A, Eyser, O, Grosnick, D, Huang, H Z, Wang, F, Srivastava, B, Ye Z, Wang, G, Kramarik, L, Singha, S, Putschke, J, Brandenburg, J D, Feng, C J, Gagliardi, C A, Wang, P, Ma, Y G, Longacre, R S, Morozov, D A, Wang, Z, Wang, Y, Zhang, S, Svirida, D N, Zhang, Y, Xiao, Z G, Zhang, Z, Cheng, J, Liu, H, Zhang, D, Quintero, A, Lisa, M A, Vokal, S, Liu, F, Zurek, M, Tribedy, P

2020

Overview

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 detector 1 – 3 at the Relativistic Heavy Ion Collider, we measure the Λ hyperon binding energy B Λ for the hypertriton, and find that it differs from the widely used value 4 and from predictions 5 – 8 , where the hypertriton is treated as a weakly bound system. Our results place stringent constraints on the hyperon–nucleon interaction 9 , 10 and have implications for understanding neutron star interiors, where strange matter may be present 11 . 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. The STAR collaboration reports a measurement of the mass difference and binding energy of the hypertriton and its antiparticle. This work constrains the hyperon–nucleon interaction and allows us to test the CPT theorem in a nucleus with strangeness.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Publishing Group (NPG)
• Subject: 639/766/387/1126 / 639/766/419/1131 / Antiparticles / Atomic / Binding energy / Classical and Continuum Physics / Complex Systems / Condensed Matter Physics / Conjugation / experimental nuclear physics / experimental particle physics / Heavy ions / Hypernuclei / Letter / Magnetic moments / Mathematical and Computational Physics / Molecular / Neutron stars / Nuclei (nuclear physics) / Nucleons / Optical and Plasma Physics / Physics / Physics and Astronomy / Quarks / Relativistic Heavy Ion Collider / Strangeness / Symmetry / Theorems / Theoretical