Search for D{sup 0}-{bar D}{sup 0} Mixing Using Semileptonic Decay Modes

Based on an 87-fb{sup -1} dataset collected by the BABAR detector at the PEP-II asymmetric-energy B-Factory, a search for D{sup 0}-{bar D}{sup 0} mixing has been made using the semileptonic decay modes D*{sup +} --> {pi}{sup +} D{sup 0}{sub z} D{sup 0} --> K*{epsilon}{nu} (+c.c.). The use of these modes allows unambiguous flavor tagging and a combined fit of the D{sup 0} decay time and D*{sup +}-D{sup 0} mass difference ({Delta}M) distributions. The high-statistics sample of unmixed semileptonic D{sup 0} decays is used to model the {Delta}M distribution and time-dependence of mixed events directly from the data. Neural networks are used to select events and reconstruct the D{sup 0}. A result consistent with no charm mixing has been obtained. R{sub mix} = 0.0023 {+-} 0.0012 {+-} 0.0004. This corresponds to an upper limit of R{sub mix} < 0.0042 (90% CL).