Search for Neutral D Meson Mixing using Semileptonic Decays

Based on a 87 fb{sup -1} dataset, a search for D{sup 0}-{bar D}{sup 0} mixing is made using the semileptonic decay modes D*{sup +} {yields} {pi}{sup +} D{sup 0}, D{sup 0} {yields} [K/K*]e{nu} (+c.c.) at the B-Factory facility at the Stanford Linear Accelerator Center. These modes offer unambiguous initial and final-state charm flavor tags, and allow the combined use of the D{sup 0} lifetime and D*{sup +}-D{sup 0} mass difference ({Delta}M) in a global likelihood fit. The high-statistics sample of reconstructed unmixed semileptonic D{sup 0} decays is used to model both the {Delta}M distribution and the time-dependence of mixed events directly from the data. Neural networks are used both to select events and to fully reconstruct the D{sup 0}. A result consistent with no charm mixing has been obtained, R{sub mix} < 0.0047 (95% C.L.) and R{sub mix} < 0.0043 (90% C.L.). The lowest current published limit on semileptonic charm mixing is 0.005 (90% C.L.) (E791, E.M. Aitala et al. Phys.Rev.Lett. 77 2384 (1996)). The current best published limit using any analysis technique on the total rate of charm mixing is 0.0016 (95% C.L.) (Bab K{pi} mixing, B. Aubert et al., Phys. Rev. Lett. 91 171801 (2003))