Measurement of the B → D̅ ^((*))D^((*))K branching fractions

We present a measurement of the branching fractions of the 22 decay channels of the B^0 and B+ mesons to D̅ ^((*))D^((*))K, where the D^((*)) and D̅ ^((*)) mesons are fully reconstructed. Summing the 10 neutral modes and the 12 charged modes, the branching fractions are found to be B(B^0→D̅6((*))D^((*))K)=(3.68 ± 0.10 ± 0.24)% and B(B^+→D̅ ^((*))D^((*))K)=(4.05 ± 0.11 ± 0.28)%, where the first uncertainties are statistical and the second systematic. The results are based on 429  fb^(-1) of data containing 471 × 10^6BB̅ pairs collected at the Υ(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory

Limits on τ lepton-flavor violating decays into three charged leptons

A search for the neutrinoless, lepton-flavor violating decay of the τ lepton into three charged leptons has been performed using an integrated luminosity of 468  fb^(-1) collected with the BABAR detector at the PEP-II collider. In all six decay modes considered, the numbers of events found in data are compatible with the background expectations. Upper limits on the branching fractions are set in the range (1.8–3.3)×10^(-8) at 90% confidence level

Search for Production of Invisible Final States in Single-Photon Decays of Y(1S)

We search for single-photon decays of the Υ(1S) resonance, Υ → γ + invisible, where the invisible state is either a particle of definite mass, such as a light Higgs boson A^0, or a pair of dark matter particles, χχ̅ . Both A^0 and χ are assumed to have zero spin. We tag Υ(1S) decays with a dipion transition Υ(2S)→π^+π^-Υ(1S) and look for events with a single energetic photon and significant missing energy. We find no evidence for such processes in the mass range m_(A^0 ≤ 9.2  GeV and m_χ ≤ 4.5  GeV in the sample of 98×10^6 Υ(2S) decays collected with the BABAR detector and set stringent limits on new physics models that contain light dark matter states

Measurement of the γγ^*→η_c transition form factor

We study the reaction e^+e^-→e^+e^-η_c, η_c→K_SK^±π^∓ and obtain η_c mass and width values 2982.2±0.4±1.6  MeV/c^2 and 31.7±1.2±0.8  MeV, respectively. We find Γ(η_c→γγ)B(ηc→KK π)=0.374±0.009±0.031  keV, and measure the γγ^*→η_c transition form factor in the momentum transfer range from 2 to 50  GeV^2. The analysis is based on 469  fb^(-1) of integrated luminosity collected at PEP-II with the BABAR detector at e^+e^- center-of-mass energies near 10.6 GeV

Search for B^+ meson decay to a_(1)^(+)(1260)K^(*0)(892)

We present a search for the decay B^+ → a_(1)^(+)(1260)K^(*0)(892). The data, collected with the BABAR detector at the SLAC National Accelerator Laboratory, represent 465 × 10^(6)BB(overbar) pairs produced in e^(+)e^(-) annihilation at the energy of the Υ(4S). We find no significant signal and set an upper limit at 90% confidence level on the product of branching fractions B(B^(+) → a_(1)^(+)(1260)K^(*0)(892)) × B(a_(1)^(+)(1260) → π^(+)π^(-)π^(+)) of 1.8 × 10^(-6)

Search for CP violation using T-odd correlations in D^0→K^+K^-π^+π^- decays

We search for CP violation in a sample of 4.7×10^4 Cabibbo suppressed D^0→K^+K^-π^+π^- decays. We use 470  fb^(-1) of data recorded by the BABAR detector at the PEP-II asymmetric-energy e^+e^- storage rings running at center-of-mass energies near 10.6 GeV. CP violation is searched for in the difference between the T-odd asymmetries, obtained using triple product correlations, measured for D^0 and D[overbar]^0 decays. The measured CP violation parameter is A_T=(1.0±5.1_(stat)±4.4_(syst))×10^(-3)

Analysis of the D^+ → K^-π^+e^+ν_e decay channel

Using 347.5  fb^(-1) of data recorded by the BABAR detector at the PEP-II electron-positron collider, 244×10^3 signal events for the D^+ → K^-π^+e^+ν_e decay channel are analyzed. This decay mode is dominated by the K̅ ^*(892)^0 contribution. We determine the K̅ ^*(892)^0 parameters: m_(K^*(892)^0)=(895.4±0.2±0.2)  MeV/c^2, Γ_(K^*(892)^0)=(46.5±0.3±0.2)  MeV/c^2, and the Blatt-Weisskopf parameter r_(BW) =2.1±0.5±0.5  (GeV/c)^-1, where the first uncertainty comes from statistics and the second from systematic uncertainties. We also measure the parameters defining the corresponding hadronic form factors at q^2 = 0 (r_V = ^(V(0))/_(A1(0)) = 1.463 ± 0.017 ± 0.031, r_2 = _(A1(0)) ^(A2(0))= 0.801±0.020±0.020) and the value of the axial-vector pole mass parametrizing the q^2 variation of A_1 and A_2: m_A=(2.63±0.10±0.13)  GeV/c^2. The S-wave fraction is equal to (5.79±0.16±0.15)%. Other signal components correspond to fractions below 1%. Using the D^+ → K^-π^+π^+ channel as a normalization, we measure the D^+ semileptonic branching fraction: B(D^+ → K^-π^+e^+ν_e)=(4.00±0.03±0.04±0.09)×10^(-2), where the third uncertainty comes from external inputs. We then obtain the value of the hadronic form factor A_1 at q^2=0: A_1(0)=0.6200±0.0056±0.0065±0.0071. Fixing the P-wave parameters, we measure the phase of the S wave for several values of the Kπ mass. These results confirm those obtained with Kπ production at small momentum transfer in fixed target experiments