We search for B0 meson decays into two-body combinations of K0, η, η′, and mesons in 324×106 BB̄ pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We measure the following branching fractions (upper limits at 90% confidence level) in units of 10-6: B(B0→ηK0)=1.8-0.6+0.7±0.1(<2.9), B(B0→ηη)=1.1-0.4+0.5±0.1(<1.8), B(B0→η)=0. 1±0.2±0.1(<0.6), B(B0→η′)=0.2-0.3+0.4±0. 1(<1.0), and B(B0→η′η′)=1.0-0.6+0.8±0. 1(<2.4), where the first error is statistical and the second systematic. © 2006 The American Physical Society.

We report the results of a search for T, CP, CPT, and violation in B0-B0 mixing using an inclusive dilepton sample collected by the BABAR experiment at the PEP-II factory. Using a sample of 232 x 10(6) BB pairs, we measure the T and CP violation parameter |q/p| - 1 = (-0.8 +/- 2.7(stat) +/- 1.9(syst) x 10(-3), and the CPT and CP parameters Imz = (13.9 +/- 7.3(stat) +/- 3.2(syst)) x 10(-3) and Delta Gamma x Rez = (7.1 +/- 3.9(stat) +/- 2.0(stat)) x 10(-3) ps(-1). The statistical correlation between the measurements of Imz and Delta Gamma x Rez is 76%.

A search for charmed baryons decaying to D(0)p reveals two states: the Lambdac(2880)+ baryon and a previously unobserved state at a mass of [2939.8+/-1.3(stat)+/-1.0(syst)] MeV/c2 and with an intrinsic width of [17.5+/-5.2(stat)+/-5.9(syst)] MeV. Consistent and significant signals are observed for the K(-)pi(+) and K(-)pi(+)pi(-)pi(+) decay modes of the D0 in 287 fb(-1) annihilation data recorded by the BABAR detector at a center-of-mass energy of 10.58 GeV. There is no evidence in the D+p spectrum of doubly charged partners. The mass and intrinsic width of the Lambdac(2880)+ baryon and relative yield of the two baryons are also measured.

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.

A search for the nonconservation of lepton flavor number in the decay tau(+/-) --> mu(+/-) has been performed using 2.07 x 10(8) e(+ )e(-) tau(+) tau(-) events produced at a center-of-mass energy near 10.58 GeV with the BABAR detector at the PEP-II storage ring. We find no evidence for a signal and set an upper limit on the branching ratio of Beta(tau(+/-) --> mu(+/-) gamma) < 6.8 x 10(-8) at 90% confidence level.

Using a data sample corresponding to an integrated luminosity of 342 fb(-1) collected with the BABAR detector at the SLAC PEP-II electron-positron storage ring operating at a center-of-mass energy near 10.58 GeV, we measure B(tau(-)--> pi(-)pi(-)pi+nu(tau)(ex.K(S0))=(8.83+/-0.01+/-0.13)%, B(tau(-) -->K(-)pi(-)pi+nu tau(ex.K(S0))=(0.273+/-0.002+/-0.009)%, B(tau(-) -->K(-)pi(-)K+nu tau)=(0.1346+/-0.0010+/-0.0036)%, and B(tau(-) -->K(-)K(-)K+nu tau)=(1.58+/-0.13+/-0.12)x10;{-5}, where the uncertainties are statistical and systematic, respectively. These include significant improvements over previous measurements and a first measurement of B(tau(-) -->K(-)K(-)K+nu tau) in which no resonance structure is assumed. We also report a first measurement of B(tau(-) -->var phi(-)nu tau)=(3.42+/-0.55+/-0.25)x10(-5), a new measurement of B(tau(-) -->var phi K(-)nu tau)=(3.39+/-0.20+/-0.28)x10(-5) and a first upper limit on B(tau(-) -->K(-)K(-)K+nu tau(ex.var phi)).