Decay rate and asymmetries of Σ+ → pμ + μ

Xiao Gang He, Jusak Tandean, German Valencia

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11 Citations (Scopus)


The LHCb Collaboration has recently reported evidence for the rare hyperon decay Σ+ → pμ+μ that is consistent with the standard model expectation. Motivated by this new result we revisit the calculation of this mode including both long and short distance contributions. In the standard model this mode is completely dominated by long distance physics and thus subject to large uncertainties. We present a range of predictions for the rate, the dimuon invariant mass spectrum, and a muon polarization asymmetry that covers these uncertainties as well as known constraints. We study the interplay between short and long distance contributions which could result in additional asymmetries, but we find that they are negligible within the standard model. We propose a parameterization of these asymmetries in terms of a couple of constants that can arise from new physics.

Original languageEnglish
Article number40
Number of pages20
JournalJournal of High Energy Physics
Issue number10
Publication statusPublished - 5 Oct 2018


  • Beyond Standard Model
  • Chiral Lagrangians
  • Effective Field Theories
  • Nonperturbative Effects

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