24,573 research outputs found

    Rescattering effects in B_{u,d,s}(bar) to D P, D(bar) P decays

    Full text link
    We study quasi-elastic rescattering effects in B_{u,d,s}(bar) to DP, D(bar)P decays, where P is a light pseudoscalar. The updated measurements of B_{u,d}(bar) to DP decays are used to extract the effective Wilson coefficients a^{eff}_1 ~ 0.90, a^{eff}_2 ~ 0.23, three strong phases delta ~ 53 degree, theta ~ 18 degree, sigma ~ -88 degree, and the mixing angle tau ~ 9 degree. This information is used to predict rates of nineteen B_{s}(bar) to DP and B_{u,d,s}(bar) to D(bar)P decay modes, including modes of interests in the gamma/phi_3 program. Many decay rates are found to be enhanced. In particular, the B_s(bar) to D0 K0 rate is predicted to be 8\times 10^{-4}, which could be measured soon. The rescattering effects on the corresponding B_{u,d,s}(bar) to D(bar)P, DP amplitude ratios r_B, r_{B_s}, and the relative strong phases delta_B, delta_{B_s} are studied. Although the decay rates are enhanced in most cases, r_{B,B_s} values are similar to factorization expectation.Comment: 16 page

    Spin-current injection and detection in strongly correlated organic conductor

    Full text link
    Spin-current injection into an organic semiconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br\rm{\kappa\text{-}(BEDT\text{-}TTF)_2Cu[N(CN)_2]Br} film induced by the spin pumping from an yttrium iron garnet (YIG) film. When magnetization dynamics in the YIG film is excited by ferromagnetic or spin-wave resonance, a voltage signal was found to appear in the κ-(BEDT-TTF)2Cu[N(CN)2]Br\rm{\kappa\text{-}(BEDT\text{-}TTF)_2Cu[N(CN)_2]Br} film. Magnetic-field-angle dependence measurements indicate that the voltage signal is governed by the inverse spin Hall effect in κ-(BEDT-TTF)2Cu[N(CN)2]Br\rm{\kappa\text{-}(BEDT\text{-}TTF)_2Cu[N(CN)_2]Br}. We found that the voltage signal in the κ-(BEDT-TTF)2Cu[N(CN)2]Br\rm{\kappa\text{-}(BEDT\text{-}TTF)_2Cu[N(CN)_2]Br}/YIG system is critically suppressed around 80 K, around which magnetic and/or glass transitions occur, implying that the efficiency of the spin-current injection is suppressed by fluctuations which critically enhanced near the transitions

    Fermi resonance-algebraic model for molecular vibrational spectra

    Full text link
    A Fermi resonance-algebraic model is proposed for molecular vibrations, where a U(2) algebra is used for describing the vibrations of each bond, and Fermi resonances between stretching and bending modes are taken into account. The model for a bent molecule XY_2 and a molecule XY_3 is successfully applied to fit the recently observed vibrational spectrum of the water molecule and arsine (AsH_3), respectively, and results are compared with those of other models. Calculations show that algebraic approaches can be used as an effective method for describing molecular vibrations with small standard deviations

    Entanglement detection beyond the CCNR criterion for infinite-dimensions

    Get PDF
    In this paper, in terms of the relation between the state and the reduced states of it, we obtain two inequalities which are valid for all separable states in infinite-dimensional bipartite quantum systems. One of them provides an entanglement criterion which is strictly stronger than the computable cross-norm or realignment (CCNR) criterion.Comment: 11 page

    Unsupervised Feature Selection with Adaptive Structure Learning

    Full text link
    The problem of feature selection has raised considerable interests in the past decade. Traditional unsupervised methods select the features which can faithfully preserve the intrinsic structures of data, where the intrinsic structures are estimated using all the input features of data. However, the estimated intrinsic structures are unreliable/inaccurate when the redundant and noisy features are not removed. Therefore, we face a dilemma here: one need the true structures of data to identify the informative features, and one need the informative features to accurately estimate the true structures of data. To address this, we propose a unified learning framework which performs structure learning and feature selection simultaneously. The structures are adaptively learned from the results of feature selection, and the informative features are reselected to preserve the refined structures of data. By leveraging the interactions between these two essential tasks, we are able to capture accurate structures and select more informative features. Experimental results on many benchmark data sets demonstrate that the proposed method outperforms many state of the art unsupervised feature selection methods

    B→DsπB \to D_s \pi and the tree amplitude in B→π+π−B \to \pi^+ \pi^-

    Full text link
    The recently-observed decay B0→Ds+π−B^0 \to D_s^+ \pi^- is expected to proceed mainly by means of a tree amplitude in the factorization limit: B0→π−(W+)∗B^0 \to \pi^- {(W^+)}^*, (W+)∗→Ds+{(W^+)}^* \to D_s^+. Under this assumption, we predict the corresponding contribution of the tree amplitude to B0→π+π−B^0 \to \pi^+ \pi^-. We indicate the needed improvements in data that will allow a useful estimate of this amplitude with errors comparable to those accompanying other methods. Since the factorization hypothesis for this process goes beyond that proved in most approaches, we also discuss independent tests of this hypothesis.Comment: 7 pages, LaTeX, 1 figure, to be submitted to Phys. Rev. D (Brief Reports

    Spectroscopic observations of a flare-related coronal jet

    Full text link
    Coronal jets are ubiquitous in active regions (ARs) and coronal holes. In this paper, we study a coronal jet related to a C3.4 circular-ribbon flare in active region 12434 on 2015 October 16. Two minifilaments were located under a 3D fan-spine structure before flare. The flare was generated by the eruption of one filament. The kinetic evolution of the jet was divided into two phases: a slow rise phase at a speed of ∼\sim131 km s−1^{-1} and a fast rise phase at a speed of ∼\sim363 km s−1^{-1} in the plane-of-sky. The slow rise phase may correspond to the impulsive reconnection at the breakout current sheet. The fast rise phase may correspond to magnetic reconnection at the flare current sheet. The transition between the two phases occurred at ∼\sim09:00:40 UT. The blueshifted Doppler velocities of the jet in the Si {\sc iv} 1402.80 {\AA} line range from -34 to -120 km s−1^{-1}. The accelerated high-energy electrons are composed of three groups. Those propagating upward along open field generate type \textrm{III} radio bursts, while those propagating downward produce HXR emissions and drive chromospheric condensation observed in the Si {\sc iv} line. The electrons trapped in the rising filament generate a microwave burst lasting for ≤\le40 s. Bidirectional outflows at the base of jet are manifested by significant line broadenings of the Si {\sc iv} line. The blueshifted Doppler velocities of outflows range from -13 to -101 km s−1^{-1}. The redshifted Doppler velocities of outflows range from ∼\sim17 to ∼\sim170 km s−1^{-1}. Our multiwavelength observations of the flare-related jet are in favor of the breakout jet model and are important for understanding the acceleration and transport of nonthermal electrons.Comment: 11 pages, 13 figures, accepted for publication in A&

    Tripartite phase separation of two signal effectors with vesicles priming B cell responsiveness.

    Get PDF
    Antibody-mediated immune responses rely on antigen recognition by the B cell antigen receptor (BCR) and the proper engagement of its intracellular signal effector proteins. Src homology (SH) 2 domain-containing leukocyte protein of 65 kDa (SLP65) is the key scaffold protein mediating BCR signaling. In resting B cells, SLP65 colocalizes with Cbl-interacting protein of 85 kDa (CIN85) in cytoplasmic granules whose formation is not fully understood. Here we show that effective B cell activation requires tripartite phase separation of SLP65, CIN85, and lipid vesicles into droplets via vesicle binding of SLP65 and promiscuous interactions between nine SH3 domains of the trimeric CIN85 and the proline-rich motifs (PRMs) of SLP65. Vesicles are clustered and the dynamical structure of SLP65 persists in the droplet phase in vitro. Our results demonstrate that phase separation driven by concerted transient interactions between scaffold proteins and vesicles is a cellular mechanism to concentrate and organize signal transducers
    • …
    corecore