Space-by-time non-negative matrix factorization for single-trial decoding of M/EEG activity

We develop a novel methodology for the single-trial analysis of multichannel time-varying neuroimaging signals. We introduce the space-by-time M/EEG decomposition, based on Non-negative Matrix Factorization (NMF), which describes single-trial M/EEG signals using a set of non-negative spatial and temporal components that are linearly combined with signed scalar activation coefficients. We illustrate the effectiveness of the proposed approach on an EEG dataset recorded during the performance of a visual categorization task. Our method extracts three temporal and two spatial functional components achieving a compact yet full representation of the underlying structure, which validates and summarizes succinctly results from previous studies. Furthermore, we introduce a decoding analysis that allows determining the distinct functional role of each component and relating them to experimental conditions and task parameters. In particular, we demonstrate that the presented stimulus and the task difficulty of each trial can be reliably decoded using specific combinations of components from the identified space-by-time representation. When comparing with a sliding-window linear discriminant algorithm, we show that our approach yields more robust decoding performance across participants. Overall, our findings suggest that the proposed space-by-time decomposition is a meaningful low-dimensional representation that carries the relevant information of single-trial M/EEG signals

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

Observation of η_c(1S) and η_c(2S) decays to K^+K^-π^+π^-π^0 in two-photon interactions

We study the processes γγ→K_S^0K^±π^∓ and γγ→K^+K^-π^+π-π^0 using a data sample of 519.2fb^(-1) recorded by the BABAR detector at the PEP-II asymmetric-energy e^+e^- collider at center-of-mass energies near the Υ(nS) (n=2, 3, 4) resonances. We observe the η_c(1S), χ_(c0)(1P) and η_c(2S) resonances produced in two-photon interactions and decaying to K^+K^-π^+π^-π^0, with significances of 18.1, 5.4 and 5.3 standard deviations (including systematic errors), respectively, and report 4.0σ evidence of the χ_(c2)(1P) decay to this final state. We measure the η_c(2S) mass and width in K_S^0K^±π^∓ decays, and obtain the values m(η_c(2S))=3638.5±1.5±0.8  MeV/c^2 and Γ(η_c(2S))=13.4±4.6±3.2  MeV, where the first uncertainty is statistical and the second is systematic. We measure the two-photon width times branching fraction for the reported resonance signals, and search for the χ_(c2)(2P) resonance, but no significant signal is observed

Evidence for the decay X(3872)→J/ψω

We present a study of the decays B^(0,+)→J/ψπ^+π^-π^0K^(0,+), using 467×10^6 BB[overbar] pairs recorded with the BABAR detector. We present evidence for the decay mode X(3872)→J/ψω, with product branching fractions B(B^+→X(3872)K^+)×B(X(3872)→J/ψω)=[0.6±0.2(stat)±0.1(syst)]×10^(-5), and B(B^0→X(3872)K^0)×B(X(3872)→J/ψω)=[0.6±0.3(stat)±0.1(syst)]×10^(-5). A detailed study of the π^+π^-π^0 mass distribution from X(3872) decay favors a negative-parity assignment

Study of B → πlν and B → ρlν decays and determination of |V_(ub)|

We present an analysis of exclusive charmless semileptonic B-meson decays based on 377 × 10^6 BB̅ pairs recorded with the BABAR detector at the Υ(4S) resonance. We select four event samples corresponding to the decay modes B^0 → π^-ℓ^+ν, B^+ → π^0ℓ^+ν, B^0 → ρ^-ℓ^+ν, and B^+ → ρ^0ℓ^+ν and find the measured branching fractions to be consistent with isospin symmetry. Assuming isospin symmetry, we combine the two B → πℓν samples, and similarly the two B → ρℓν samples, and measure the branching fractions B(B^0→π^-ℓ^+ν)=(1.41 ± 0.05 ± 0.07) × 10^(-4) and B(B^0 → ρ^-ℓ^+ν)=(1.75 ± 0.15 ± 0.27) × 10^(-4), where the errors are statistical and systematic. We compare the measured distribution in q^2, the momentum transfer squared, with predictions for the form factors from QCD calculations and determine the Cabibbo-Kobayashi-Maskawa matrix element |V_(ub)|. Based on the measured partial branching fraction for B → πℓν in the range q^2 < 12  GeV^2 and the most recent QCD light-cone sum-rule calculations, we obtain |V_(ub)|=(3.78 ± 0.13^(+0.55)_(-0.40)) × 10^(-3), where the errors refer to the experimental and theoretical uncertainties. From a simultaneous fit to the data over the full q^2 range and the FNAL/MILC lattice QCD results, we obtain |V_(ub)|=(2.95 ± 0.31) × 10^(-3) from B → πℓν, where the error is the combined experimental and theoretical uncertainty

Measurements of branching fractions, polarizations, and direct CP-violation asymmetries in B^+ → ρ^0K^(*+) and B^+ → f_0 (980)K^(*+) decays

We present measurements of the branching fractions, longitudinal polarization, and direct CP-violation asymmetries for the decays B^+→ρ^0K^(*+) and B^+→f_0(980)K^(*+) with a sample of (467±5)×10^6BB̅ pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at the SLAC National Accelerator Laboratory. We observe B+→ρ0K*+ with a significance of 5.3σ and measure the branching fraction B(B^+→ρ^0K^(*+))=(4.6±1.0±0.4)×10^(-6), the longitudinal polarization f_L=0.78±0.12±0.03, and the CP-violation asymmetry A_(CP)=0.31±0.13±0.03. We observe B^+→f_0(980)K^(*+) and measure the branching fraction B(B^+→f_0(980)K^(*+))×B(f_0(980)→π^+π^-)=(4.2±0.6±0.3)×10^(-6) and the CP-violation asymmetry A_(CP)=-0.15±0.12±0.03. The first uncertainty quoted is statistical and the second is systematic

Study of B → Xγ decays and determination of |V_(td)/V_(ts)|

Using a sample of 471×10^6 BB̅[overbar] events collected with the BABAR detector, we study the sum of seven exclusive final states B→X_(s(d))γ, where X_(s(d)) is a strange (nonstrange) hadronic system with a mass of up to 2.0  GeV/c^2. After correcting for unobserved decay modes, we obtain a branching fraction for b→dγ of (9.2±2.0(stat)±2.3(syst))×10^(-6) in this mass range, and a branching fraction for b→sγ of (23.0±0.8(stat)±3.0(syst))×10^(-5) in the same mass range. We find B[script](b→dγ)/B[script](b→sγ)=0.040±0.009(stat)±0.010(syst), from which we determine |V_(td)/V_(ts)|=0.199±0.022(stat)±0.024(syst)±0.002(th)