Precision measurement of D meson mass differences

Using three- and four-body decays of D mesons produced in semileptonic b-hadron decays, precision measurements of D meson mass differences are made together with a measurement of the D ⁰ mass. The measurements are based on a dataset corresponding to an integrated luminosity of 1.0 fb ^-1 collected in pp collisions at 7 TeV. Using the decay D ⁰ → K ⁺ K ^- K ^- π ⁺, the D ⁰ mass is measured to be M(D ⁰)=1864. 75± 0.15(stat)± 0.11(syst) MeV/c ². The mass differences M(D ⁺)-M(D ⁰=4.76± 0.12(stat)± MeV/c ². M(D _s ⁺)-M(D ⁺)=98.68± 0.03(stat)± 0.04(syst) MeV/c ² are measured using the D ⁰ → K ⁺ K ^- π ⁺ π ^- and D _s ⁺ to K ⁺K ^-π ⁺ modes.