Measurement of the 2 ν β β Decay Rate and Spectral Shape of Mo 100 from the CUPID-Mo Experiment

Journal Article · 17 October 2023 · Physical Review Letters

DOI: https://doi.org/10.1103/physrevlett.131.162501 · OSTI ID:2229036

Augier, C.; Barabash, A.  S.; Bellini, F.; Benato, G.; Beretta, M.; Bergé, L.; Billard, J.; Borovlev, Yu  A.; Cardani, L.; Casali, N.; Cazes, A.; Celi, E.; Chapellier, M.; Chiesa, D.; Dafinei, I.; Danevich, F.  A.; De Jesus, M.; Dixon, T. ; Dumoulin, L.; Eitel, K. ; Ferri, F.; Fujikawa, B.  K.; Gascon, J.; Gironi, L.; Giuliani, A.; Grigorieva, V.  D.; Gros, M.; Helis, D.  L.; Huang, H.  Z.; Huang, R.; Imbert, L.; Johnston, J.; Juillard, A.; Khalife, H.; Kleifges, M.; Kobychev, V.  V.; Kolomensky, Yu  G.; Konovalov, S.  I.; Kotila, J.; Loaiza, P.; Ma, L.; Makarov, E.  P.; de Marcillac, P.; Mariam, R.; Marini, L.; Marnieros, S.; Navick, X. -F.; Nones, C.; Norman, E.  B.; Olivieri, E.; Ouellet, J.  L.; Pagnanini, L.; Pattavina, L.; Paul, B.; Pavan, M.; Peng, H.; Pessina, G.; Pirro, S.; Poda, D.  V.; Polischuk, O.  G.; Pozzi, S.; Previtali, E.; Redon, Th; Rojas, A.; Rozov, S.; Sanglard, V.; Scarpaci, J.  A.; Schmidt, B.; Shen, Y.; Shlegel, V.  N.; Šimkovic, F.; Singh, V.; Tomei, C.; Tretyak, V.  I.; Umatov, V.  I.; Vagneron, L.; Velázquez, M.; Ware, B.; Welliver, B.; Winslow, L.; Xue, M.; Yakushev, E.; Zarytskyy, M.; Zolotarova, A.  S.

Neutrinoless double beta decay (0νββ) is a yet unobserved nuclear process that would demonstrate Lepton number violation, a clear evidence of beyond standard model physics. The process two neutrino double beta decay (2νββ) is allowed by the standard model and has been measured in numerous experiments. In this Letter, we report a measurement of 2νββ decay half-life of ¹⁰⁰Mo to the ground state of ¹⁰⁰Ru of [7.07±0.02(stat)±0.11(syst)]×10¹⁸ yr by the CUPID-Mo experiment. With a relative precision of ±1.6% this is the most precise measurement to date of a 2νββ decay rate in ¹⁰⁰Mo. In addition, we constrain higher-order corrections to the spectral shape, which provides complementary nuclear structure information. We report a novel measurement of the shape factor ξ_3,1=0.45±0.03(stat)±0.05(syst) based on a constraint on the ratio of higher-order terms from theory, which can be reliably calculated. This is compared to theoretical predictions for different nuclear models. Finally, we also extract the first value for the effective axial vector coupling constant obtained from a spectral shape study of 2νββ decay.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• Contributing Organization: CUPID-Mo Collaboration
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 2229036
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 16 Vol. 131; ISSN 0031-9007
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English