Search for D(s)⁺ → π⁺μ⁺μ^- and D(s)⁺ → π^-μ⁺μ⁺ decays

A search for non-resonant D _(s) ⁺ → π ⁺μ ⁺μ ^- and D _(s) ⁺ → π ^-μ ⁺μ ⁺ decays is performed using proton-proton collision data, corresponding to an integrated luminosity of 1.0 fb ^-1, √at s=7TeV recorded by the LHCb experiment in 2011. No signals are observed and the 90% (95%) confidence level (CL) limits on the branching fractions are found to be B(D ⁺ → π ⁺μ ⁺μ ^-)<7.3(8.3)×10 ^-8, B(D _s ⁺ → π ⁺μ ⁺μ ^-)<4.1(4.8)×10 ^-7, B(D ⁺ → π ^-μ ⁺μ ⁺)<2.2(2.5)×10 ^-8, B(D _s ⁺ → π ^-μ ⁺μ ⁺)<1.2(1.4)×10 ^-7. These limits are the most stringent to date.