Zc(4430) discovered by the Belle Collaboration and confirmed by the LHCb Collaboration in B¯0→ψ(2S)K−π+ is generally considered to be a charged charmoniumlike state that includes minimally two quarks ...and two antiquarks. Zc(4200) found in B¯0→J/ψK−π+ by Belle is also a good candidate of a charged charmoniumlike state. In this work, we propose a compelling alternative to the tetraquark-based interpretations of Zc(4430) and Zc(4200). We demonstrate that kinematical singularities in triangle loop diagrams induce a resonancelike behavior that can consistently explain the properties (spin parity, mass, width, and Argand plot) of Zc(4430) and Zc(4200) from the experimental analyses. Applying this idea to Λb0→J/ψpπ−, we also identify triangle singularities that behave like Zc(4200), but no triangle diagram is available for Zc(4430). This is consistent with LHCb's finding that their description of the Λb0→J/ψpπ− data is significantly improved by including a Zc(4200) contribution while Zc(4430) seems to hardly contribute. Even though the proposed mechanisms have uncertainty in the absolute strengths which are currently difficult to estimate, otherwise the results are essentially determined by the kinematical effects and, thus, robust.
The current and near-future neutrino-oscillation experiments require significantly improved neutrino-nucleus reaction models. Neutrino-nucleon pion production data play a crucial role to validate ...corresponding elementary amplitudes that go into such neutrino-nucleus models. Thus, the currently available data extracted from charged-current neutrino-deuteron reaction data (νμd→μ−πNN) must be corrected for nuclear effects such as the Fermi motion and final state interactions (FSI). We study νμd→μ−πNN with a theoretical model including the impulse mechanism supplemented by FSI from NN and πN rescatterings. An analysis of the spectator momentum distributions reveals that the FSI effects significantly reduce the spectra over the quasifree peak region and leads to a useful recipe to extract information of elementary νμN→μ−πN processes using νμd→μ−πNN data, with the important FSI corrections taken into account. We provide νμN→μ−πN total cross sections by correcting the deuterium bubble chamber data for the FSI and Fermi motion. The results will bring a significant improvement on neutrino-nucleus reaction models for the near-future neutrino-oscillation experiments.
The study of pion production in nuclei is important for signal and background determinations in current and future neutrino oscillation experiments. The first step, however, is to understand the pion ...production reactions at the free nucleon level. We present an exhaustive study of the charged-current and neutral-current neutrino and antineutrino pion production off nucleons, paying special attention to the angular distributions of the outgoing pion. We show, using general arguments, that parity violation and time-reversal odd correlations in the weak differential cross sections are generated from the interference between different contributions to the hadronic current that are not relatively real. Next, we present a detailed comparison of three state-of-the-art, microscopic models for electroweak pion production off nucleons, and we also confront their predictions with polarized electron data, as a test of the vector content of these models. We also illustrate the importance of carrying out a comprehensive test at the level of outgoing pion angular distributions, going beyond comparisons done for partially integrated cross sections, where model differences cancel to a certain extent. Finally, we observe that all charged and neutral current distributions show sizable anisotropies, and identify channels for which parity-violating effects are clearly visible. Based on the above results, we conclude that the use of isotropic distributions for the pions in the center of mass of the final pion-nucleon system, as assumed by some of the Monte Carlo event generators, needs to be improved by incorporating the findings of microscopic calculations.
We survey 3 years (2013–2015) of data from the Van Allen Probes related to plasmaspheric plume crossing events. We detect 194 plume crossing events, and we find that 97% of the plumes are accompanied ...by very low frequency hiss emissions. The plumes are mainly detected on the duskside or dayside. Careful examination of the hiss spectra reveals that all hiss emissions consist of obvious fine structure. Application of a band‐pass filter reveals that the fine structure is consistent with the occurrence of discrete wave packets. The hiss data display high coherency. The events are classified by location. Duskside hiss and nightside hiss tend to have extremely high polarization with no chorus at the high‐frequency end of the dynamic spectrum. The duskside hiss has a distinct upper frequency limit. On the other hand, the dawnside hiss has strong chorus elements at the upper hiss frequency, which makes the upper frequency limit ambiguous. We show that the structure of whistler mode hiss is different from artificial random noise. Although noise also has fine spectral characteristics, the polarization and waveform data are totally different from the hiss cases. Our results strongly suggest that whistler mode hiss in plasmaspheric plumes universally possesses fine structure.
Key Points
We examine 194 plume crossing events observed by the Van Allen Probes
We observe hiss emissions in 97% of the plume events
All hiss emissions have obvious fine structure
On 23 February 2014, Van Allen Probes sensors observed quite strong electromagnetic ion cyclotron (EMIC) waves in the outer dayside magnetosphere. The maximum amplitude was more than 14 nT, ...comparable to 7% of the magnitude of the ambient magnetic field. The EMIC waves consisted of a series of coherent rising tone emissions. Rising tones are excited sporadically by energetic protons. At the same time, the probes detected drastic fluctuations in fluxes of MeV electrons. It was found that the electron fluxes decreased by more than 30% during the 1 min following the observation of each EMIC rising tone emissions. Furthermore, it is concluded that the flux reduction is a nonadiabatic (irreversible) process since holes in the particle flux levels appear as drift echoes with energy dispersion. We examine the process of electron pitch angle scattering by nonlinear wave trapping due to anomalous cyclotron resonance with EMIC rising tone emissions. The energy range of precipitated electrons agrees with the presumed energy for the threshold amplitude for nonlinear wave trapping. This is the first report of rapid precipitation (<1 min) of relativistic electrons by EMIC rising tone emissions and their drift echoes in time observed by spacecraft.
Key Points
Relativistic electrons disappear following intense EMIC rising tone in a few minutes
Drift echoes of localized electron depletion are detected
This is the direct observation of rapid loss process by the nonlinear EMIC scattering
Superconductivity at interfaces has been investigated since the first demonstration of electric-field-tunable superconductivity in ultrathin films in 1960(1). So far, research on interface ...superconductivity has focused on materials that are known to be superconductors in bulk. Here, we show that electrostatic carrier doping can induce superconductivity in KTaO(3), a material in which superconductivity has not been observed before. Taking advantage of the large capacitance of the self-organized electric double layer that forms at the interface between an ionic liquid and KTaO(3) (ref. 12), we achieve a charge carrier density that is an order of magnitude larger than the density that can be achieved with conventional chemical doping. Superconductivity emerges in KTaO(3) at 50 mK for two-dimensional carrier densities in the range 2.3 × 10(14) to 3.7 × 10(14) cm(-2). The present result clearly shows that electrostatic carrier doping can lead to new states of matter at nanoscale interfaces.
Electric field control of charge carrier density has long been a key technology to tune the physical properties of condensed matter, exploring the modern semiconductor industry. One of the big ...challenges is to increase the maximum attainable carrier density so that we can induce superconductivity in field-effect-transistor geometry. However, such experiments have so far been limited to modulation of the critical temperature in originally conducting samples because of dielectric breakdown. Here we report electric-field-induced superconductivity in an insulator by using an electric-double-layer gating in an organic electrolyte. Sheet carrier density was enhanced from zero to 1014 cm−2 by applying a gate voltage of up to 3.5 V to a pristine SrTiO3 single-crystal channel. A two-dimensional superconducting state emerged below a critical temperature of 0.4 K, comparable to the maximum value for chemically doped bulk crystals, indicating this method as promising for searching for unprecedented superconducting states.
Abstract In order to create a moist environment for rapid wound healing, a hydrogel sheet composed of a blended powder of alginate, chitin/chitosan and fucoidan (ACF-HS; 60:20:2:4 w/w) has been ...developed as a functional wound dressing. ACF-HS gradually absorbed DMEM without any maceration, and fluid absorption became constant within 18 h. On application, ACF-HS was expected to effectively interact with and protect the wound in rats, providing a good moist healing environment with exudates. In addition, the wound dressing has properties such as ease of application and removal and good adherence. Full-thickness skin defects were made on the backs of rats and mitomycin C solution (1 mg/ml in saline) was applied onto the wound for 10 min in order to prepare healing-impaired wounds. After thoroughly washing out the mitomycin C, ACF-HS was applied to the healing-impaired wounds. Although normal rat wound repair was not stimulated by the application of ACF-HS, healing-impaired wound repair was significantly stimulated. Histological examination demonstrated significantly advanced granulation tissue and capillary formation in the healing-impaired wounds treated with ACF-HS on day 7, as compared to those treated with calcium alginate fiber (Kaltostat® ; Convatec Ltd., Tokyo, Japan) and those left untreated.
PDF
