Cepedello R, Deppisch FF, González L, Hati C, Hirsch M. Neutrinoless Double-β Decay with Nonstandard Majoron Emission.
PHYSICAL REVIEW LETTERS 2019;
122:181801. [PMID:
31144899 DOI:
10.1103/physrevlett.122.181801]
[Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 02/01/2019] [Indexed: 06/09/2023]
Abstract
We present a novel mode of neutrinoless double-β decay with emission of a light Majoron-like scalar particle ϕ. We assume it couples via an effective seven-dimensional operator with a (V+A) lepton current and (V±A) quark currents leading to a long-range contribution that is unsuppressed by the light neutrino mass. We calculate the total double-β decay rate and determine the fully differential shape for this mode. We find that future double-β decay searches are sensitive to scales of the order Λ_{NP}≈1 TeV for the effective operator and a light scalar m_{ϕ}<0.2 MeV, based on ordinary double-β decay Majoron searches. The angular and energy distributions can deviate considerably from that of two-neutrino double-β decay, which is the main background. We point out possible ultraviolet completions where such an effective operator can emerge.
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