Malcolm John

Abstract:

We search for B-→D0K- and B-→D*0K- and charge conjugates. Here the symbol D0 indicates decay of a D0 or D̄0 into K+π-, while the symbol D*0 indicates decay of a D*0 or D̄*0 to D0π0 or D0γ. These final states can be reached through the b→c transition B-→D(*)0K- followed by the doubly Cabibbo-Kobayashi-Maskawa (CKM)-suppressed D0→K+π-, or the b→u transition B-→D̄(*)0K- followed by the CKM-favored D̄0→K+π-. The interference of these two amplitudes is sensitive to the angle γ of the unitarity triangle. Our results are based on 232×106 Υ(4S)→BB̄ decays collected with the BABAR detector at SLAC. We find no significant evidence for these decays. We set a limit rB|A(B-→D̄0K-)/A(B-→D0K-)|<0.23 at 90% C.L. using the most conservative assumptions on the values of the CKM angle γ and the strong phases in the B and D decay amplitudes. In the case of the D* we set a 90% C.L. limit rB*2|A(B-→D̄*0K-)/A(B-→D*0K-) |2<(0.16)2 which is independent of assumptions on γ and strong phases. © 2005 The American Physical Society.

Abstract:

We search for strange-pentaquark states that have been previously reported by other experiments-the Θ(1540)+, Ξ5(1860) - , and Ξ5(1860)0-in 123fb-1 of data recorded with the BABAR detector at the PEP-II e+e- storage ring. We find no evidence for these states and set 95% confidence level upper limits on the number of Θ(1540)+ and Ξ5(1860) - pentaquarks produced per e+e- annihilation into qq̄ and per Υ(4S) decay. For qq̄ events the Θ(1540)+ [Ξ5(1860) - ] limit is about 8 [4] times lower than the rates measured for ordinary baryons of similar mass. © 2005 The American Physical Society.

Abstract:

A search for the decay of the τ lepton to seven charged pions and one or zero π0 mesons was performed using the BABAR detector at the PEP-II asymmetric-energy e+e- collider. The analysis uses 232.2fb-1 of data at center-of-mass energies on or near the Υ(4S) resonance. We observe 24 events with an expected background of 21.6±1.3 events. Without evidence for a signal, we calculate an upper limit of B(τ-→4π-3π+(π0) ντ)<3.0×10-7 at 90% confidence level. This is an improvement by nearly an order of magnitude over the previously established limit. In addition, we set upper limits for the exclusive decays τ-→4π-3π+ντ and τ-→4π-3π+π0ντ. © 2005 The American Physical Society.

Abstract:

We report on the search for the rare decays B+→D(*)+KS0 in approximately 226×106 Υ(4S)→BB̄ decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. We do not observe any significant signal and we set 90% confidence-level upper limits on the branching fractions, B(B+→D+K0)<0.5×10-5 and B(B+→D*+K0)<0.9×10-5. © 2005 The American Physical Society.

Abstract:

We have measured the process B±→ (K*±→K±π0)π0 with 232×106 Υ(4S) →BB̄ decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. From a signal yield of 89±26 events we obtain the branching fraction B(B±→K*±π0)=[6. 9±2.0(stat)±1.3(syst)]×10-6 with a statistical significance of 3.6 standard deviations including systematic uncertainties, and a charge asymmetry of 0.04±0.29(stat)±0.05(syst). © 2005 The American Physical Society.