A search is presented for the four-body decay ${B}^{0}{\rightarrow}pp\overline{p}\overline{p}$ in a sample of 471 million $B\overline{B}$ pairs collected with the BABAR detector, operated at the SLAC ...PEP-II asymmetric-energy ${e}^{+}{e}^{{-}}$ collider. The center-of-mass energy is 10.58 GeV. From a fit to the distribution of the energy-substituted mass ${m}_{\mathrm{ES}}$, the branching fraction $\mathcal{B}({B}^{0}{\rightarrow}pp\overline{p}\overline{p})=(1.1\pm{}0.5\pm{}0.2)\times{}{10}^{{-}7}$ is extracted, where the first uncertainty is statistical and the second is systematic. The significance of the signal, including the systematic uncertainty, is 2.9 standard deviations. The upper limit on the branching fraction is determined to be $2.0\times{}{10}^{{-}7}$ at 90% confidence level.
The decay τ-→K-KSντ has been studied using 430×106 e+e-→τ+τ- events produced at a center-of-mass energy around 10.6 GeV at the PEP-II collider and studied with the BABAR detector. The mass spectrum ...of the K-KS system has been measured and the spectral function has been obtained. The measured branching fraction B(τ-→K-KSντ)=(0.739±0.011(stat)±0.020(syst))×10-3 is found to be in agreement with earlier measurements.
We study the ϒ(1S) radiative decays to γπ+π− and γK+K− using data recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e+e− collider at center-of-mass energies at the ϒ(2S) ...and ϒ(3S) resonances. The ϒ(1S) resonance is reconstructed from the decay ϒ(nS)→π+π−ϒ(1S), n=2, 3. Branching fraction measurements and spin-parity analyses of ϒ(1S) radiative decays are reported for the I=0 S-wave and f2(1270) resonances in the π+π− mass spectrum, the f2′(1525) and f0(1500) in the K+K− mass spectrum, and the f0(1710) in both.
Here, we study the processes e+e- → γ ISR J/ψ , where J/ψ → π +π-π0, J/ψ → K +K-π0 , and J / ψ → K$0\atop{S}$ K ± π ∓ using a data sample of 519 fb-1 recorded with the BABAR detector operating at the ...SLAC PEP-II asymmetric-energy e+e- collider at center-of-mass energies at and near the Υ (nS) (n = 2 , 3 , 4) resonances. We measure the ratio of branching fractions R1 = $B(J/ψ →K^+K^- π^0)\atop{B(J/ψ →π^+π^- π^0)}$ and R2= $B(J/ψ →K^0_SK^±π^∓)\atop{B(J/ψ →π^+π^- π^0)}$. We perform Dalitz plot analyses of the three J/ψ decay modes and measure fractions for resonances contributing to the decays. We also analyze the J/ψ → $π^+π^- π^0$ decay using the Veneziano model. We observe structures compatible with the presence of ρ (1450) in all three J/ψ decay modes and measure the relative branching fraction: R (p(1450)) = $Bp(1450)→K^+K^-)\atop{B(p(1450)→π^+π^-)}$ +0.307 ± 0.084 (stat) ± 0.082 (sys).
We study the processes e + e - → γ ISR J / ψ , where J / ψ → π + π - π 0 , J / ψ → K + K - π 0 , and J / ψ → K$0\atop{S}$ K ± π ∓ using a data sample of 519 fb - 1 recorded with the BABAR detector ...operating at the SLAC PEP-II asymmetric-energy e + e - collider at center-of-mass energies at and near the Υ ( n S ) ( n = 2 , 3 , 4 ) resonances.
We study the processes e+e−→KS0KL0π0γ, KS0KL0ηγ, and KS0KL0π0π0γ, where the photon is radiated from the initial state, providing cross section measurements for the hadronic final states over a ...continuum of center-of-mass energies. The results are based on 469 fb−1 of data collected at or near the Υ(4S) resonance with the BABAR detector at SLAC. We present the first measurements of the e+e−→KS0KL0π0, KS0KL0η, and KS0KL0π0π0 cross sections up to a center-of-mass energy of 4 GeV and study their intermediate resonance structures. We observe J/ψ decays to all of these final states for the first time, present measurements of their J/ψ branching fractions, and search for ψ(2S) decays.
Based on the full BABAR data sample of 466.5 million $B\bar{B}$ pairs, we present measurements of the electron spectrum from semileptonic B meson decays. We fit the inclusive electron spectrum to ...distinguish Cabibbo-Kobayashi-Maskawa (CKM) suppressed B → Xueν decays from the CKM-favored B → Xceν decays, and from various other backgrounds, and determine the total semileptonic branching fraction B (B → Xeν) = ( 10.34 ± 0.04stat ± 0.2 6syst)%, averaged over B± and B0 mesons. We determine the spectrum and branching fraction for charmless B → Xueν decays and extract the CKM element | Vub| , by relying on four different QCD calculations based on the heavy quark expansion. While experimentally, the electron momentum region above 2.1 GeV / c is favored, because the background is relatively low, the uncertainties for the theoretical predictions are largest in the region near the kinematic endpoint. Detailed studies to assess the impact of these four predictions on the measurements of the electron spectrum, the branching fraction, and the extraction of the CKM matrix element |Vub| are presented, with the lower limit on the electron momentum varied from 0.8 GeV / c to the kinematic endpoint. We determine |Vub| using each of these different calculations and find, |Vub| = ( 3.794 ± 0.107exp $+ 0.292\atop{ - 0.219 SF}$ $+ 0.078 \atop{- 0.068 theory}$ ) × 10- 3 (De Fazio and Neubert), (4.563 ± 0.126exp $+ 0.230\atop {- 0.208 SF}$ $+ 0.162\atop{- 0.163 theory}$ ) ×10-3 (Bosch, Lange, Neubert, and Paz), (3.959 ± 0.104exp $+ 0.164\atop{- 0.154 SF}$ $+ 0.042\atop{ - 0.079 theory}$ ) × 10-3 (Gambino, Giordano, Ossola, and Uraltsev), (3.848 ± 0.108exp $+ 0.084\atop{ - 0.070 theory}$) × 10-3 (dressed gluon exponentiation), where the stated uncertainties refer to the experimental uncertainties of the partial branching fraction measurement, the shape function parameters, and the theoretical calculations.
We study the processes e+e−→γISRJ/ψ, where J/ψ→π+π−π0, J/ψ→K+K−π0, and J/ψ→KS0K±π∓ using a data sample of 519 fb−1 recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e+e− ...collider at center-of-mass energies at and near the Υ(nS) (n=2,3,4) resonances. We measure the ratio of branching fractions R1=B(J/ψ→K+K−π0)B(J/ψ→π+π−π0) and R2=B(J/ψ→KS0K±π∓)B(J/ψ→π+π−π0). We perform Dalitz plot analyses of the three J/ψ decay modes and measure fractions for resonances contributing to the decays. We also analyze the J/ψ→π+π−π0 decay using the Veneziano model. We observe structures compatible with the presence of ρ(1450) in all three J/ψ decay modes and measure the relative branching fraction: R(ρ(1450))=B(ρ(1450)→K+K−)B(ρ(1450)→π+π−)=0.307±0.084(stat)±0.082(sys).
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