Search for the rare c^+ p ^+ ^- decay

A search for the nonresonant c^+ p ^+ ^- decay is performed using proton-proton collision data recorded at a centre-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 c^+ p ^+ ^- 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, and resonances are also determined.