Search for the rare decay of charmed baryon Λ⁺ _𝑐 into the 𝑝⁢𝜇⁺⁢𝜇⁻ final state

A search for the nonresonant Λ⁺ _c→pμ⁺μ⁻ decay is performed using proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the LHCb experiment, corresponding to an integrated luminosity of 5.4  fb⁻¹. No evidence for the decay is found in the dimuon invariant-mass regions where the expected contributions of resonances is subdominant. The upper limit on the branching fraction of the Λ⁺ _c→pμ⁺μ⁻ decay is determined to be 2.9⁢(3.2)×10⁻⁸  at  90%(95%) confidence level. The branching fractions in the dimuon invariant-mass regions dominated by the n, p and w resonances are also determined.