Malcolm John

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.

Abstract:

We measure the branching fraction and the CP-violating asymmetry of B0→KS0π0 decays with 227 million Υ(4S)→BB̄ events collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We obtain a branching fraction B(B0→K0π0)=(11.4±0. 9±0.6)×10-6 and CP-violating asymmetry parameters CKS0π0=0.06±0.18±0.03 and SKS0π0=0.35-0.33+0.30±0.04, where the first error is statistical and the second systematic. © 2005 The American Physical Society.

Abstract:

We present a measurement of the time-dependent CP-violating asymmetries in decays of neutral B mesons to the final states D* π±, using approximately 232×106 BB̄ events recorded by the BABAR experiment at the PEP-II e+e- storage ring. Events containing these decays are selected with a partial reconstruction technique, in which only the high-momentum π± from the B decay and the low-momentum π from the D* decay are used. We measure the parameters related to 2β+γ to be aD*π=-0. 034±0.014±0.009 and cD*π =-0.019±0.022±0. 013. With some theoretical assumptions, we interpret our results in terms of the lower limits |sin (2β+γ)|>0.62(0.35) at 68% (90%) confidence level. © 2005 The American Physical Society.