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Measurement of inclusive partial branching fractions and at Belle II
No full textA sample of 365 fb of data collected by the Belle II experiment is used to measure the partial branching fractions of charmless semileptonic meson decays and determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element . Events containing a signal electron or muon and a fully reconstructed hadronic decay that constrains the signal kinematics are selected, while the rest of the event defines the hadronic system associated with the signal. To discriminate the signal from the 50-times larger background originating from CKM-favored semileptonic decays, a template fit is performed in both signal and control regions after applying an optimized selection. The partial branching fraction measured for lepton energies greater than 1 GeV in the signal meson rest frame is . From this measurement, using the Gambino, Giordano, Ossola, Uraltsev theoretical framework, is determined, where the uncertainties are experimental and theoretical, respectively. This value is consistent with the world average obtained from previous inclusive measurements. Different theoretical predictions and partial branching fractions measured in other phase-space regions, defined by additional selections on the and leptonic system masses, are also used to determine
Evidence of current-enhanced excited states in lattice QCD three-point functions
No full textExcited-state contamination remains one of the leading sources of systematic uncertainty in the precise determination of hadron structure observables from lattice QCD. In this work, I present a general mechanism, motivated by meson dominance and implemented through the variational method, that identifies which excited states are enhanced by the choice of inserted current and kinematics. The argument is supported by numerical evidence and predictions from chiral perturbation theory across different hadronic channels, in particular in the nucleon sector, and provides both conceptual insight and practical guidance for controlling excited-state effects in hadron three-point function analyses
Ultrafast radiation chemistry of glycine in aqueous solution
No full textInvestigating the ultrafast dynamics of primary biological compounds is crucial for gaining insights into radiation damage. We computationally investigate the ionization-induced dynamics of glycine in an aqueous solution. By employing fewest-switches-surface hopping simulations, we specifically address ionization in different orbital levels of the glycine molecule as well as in water molecules in its solvation shell. Upon ionization, glycine undergoes rapid fragmentation on the C–C bond, resulting in the formation of CO and the methylamine (HNHC⋅) radical. Our analysis shows that the solvation shell has little effect on the fragmentation dynamics. When ionized in water, or a deeper valence orbital of glycine, the system first relaxes to the ground state, involving the transfer of the valence hole between water and glycine. The associated redox reaction exemplifies the oxidizing power of HO⋅
Observation of W+W−γ production in pp collisions at s = 13 TeV with the ATLAS detector and constraints on anomalous quartic gauge-boson couplings
No full textThis Letter reports the observation of W+W−γ triboson production in 140 fb−1 of data collected by the ATLAS detector from proton–proton collisions at a centre-of-mass energy of s = 13 TeV at the LHC. Events with an opposite-charge eμ pair, a high transverse-momentum photon, and significant missing transverse momentum are considered. The observed (expected) significance of the signal is 5.9 (6.0) standard deviations. The measured fiducial cross-section, defined for the W+W−γ→e±μ∓νν¯γ final state is 6.2 ± 0.8 (stat.) ± 0.6 (sys.) fb, in good agreement with the Standard Model prediction of 6.1−0.7+1.0 fb. Constraints on the Wilson coefficients of 13 dimension-8 operators describing physics beyond the Standard Model through anomalous quartic gauge-boson couplings are derived using the effective field theory framework
Chirality Switching in by Highly Charged Ion Irradiation
No full textIn layered materials, charge density waves can occur in distinct chiral phases, which can be switched. We use Xe ions at a kinetic energy of 22.5 keV to switch the commensurate charge density wave chirality on the nanoscale in 1-TaS at 50 K. Changes in spectral weight, density of states, and band structure are monitored by angle-resolved photoemission spectroscopy. We find that changes in the band structure are most pronounced at the charge density wave gaps and that chirality switches gradually with ion fluence, saturating to near-full handedness reversal at ≳4000 ions/μm. We discuss a scenario for ion-induced chiral switching within the framework of intense, spatially confined electronic excitations, which induce a phase transition and defect-stabilized grain boundaries
Probing early parton emissions in heavy ion collisions using the Lund jet plane
No full textIn scattering experiments, high-virtuality partons, i.e., quarks and gluons, initiate a series of additional parton emissions to create collimated sprays of particles known as jets. This paper presents a measurement of the Lund jet plane (LJP) of high-energy jets produced in lead-lead (PbPb) collisions and compares the results to data for proton-proton (pp) collisions. The LJP is formed by iteratively declustering the constituents of a jet into consecutive emissions and recording the relative transverse momentum () and angle of the resulting emission with respect to its emitter. The angular distributions of two different slices of the LJP are investigated for jets with radius parameter of 0.4 and transverse momentum in the range 2001000 GeV. The PbPb (pp) data were recorded by the CMS experiment in 2018 (2017) and correspond to an integrated luminosity of 1.7 nb (301 pb) at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The measurement was designed to test whether the earliest jet emissions are produced before the formation of the quark-gluon plasma (QGP) in PbPb collisions. Within the experimental uncertainties, no significant difference is observed between the angular distribution of high- emissions in \pp and PbPb collisions, which is consistent with these emissions occurring early in the jet evolution, before substantial interaction with the QGP
openCost für DSpace : Aktuelle Entwicklungen bei CSIC
No full textIm Netzwerk spanischer wissenschaftlicher Bibliotheken (Red de BibliotecasUniversitarias y Científicas Españolas, REBUIN) haben sich die 76Universitätsbibliotheken des Landes und die Bibliotheken des Oberster Rat fürwissenschaftliche Forschung (Consejo Superior de Investigaciones Científicas,CSIC), der größten Forschungseinrichtung Spaniens zusammengeschlossen. Um OpenAccess Kosten trotz der diversen Ausrichtung einheitlich zu erfassen unddarzustellen hat die Arbeitsgruppe „Institutional Repositories“ von REBUINbegonnen openCost für alle beteiligten Einrichtungen zu implementieren. DieseImplementation wird von der Untergruppe „DSpace-Repositorien” vorangetrieben.Nach einer kurzen Vorstellung des Entwicklungsstands in Spanien soll der Standder openCost-Implementation in Deutschland und eventuelleNachnutzungsmöglichkeiten diskutiert werden
Crystal structure of MnN resolved using x-ray absorption fine structure
No full textThe potential of manganese mononitride (MnN) as an antiferromagnetic material for exchange bias applications is significant, yet its crystal structure is a subject of ongoing debate. Early 3 transition metal mononitrides, such as TiN, and VN, are well-known to crystallize in the rock salt (RS) structure, whereas later ones, like CoN and FeN, favor the zinc blende (ZB) structure. The structural ambiguity of MnN, positioned midway in the 3 series, necessitates further investigation. This study employs a comprehensive x-ray absorption fine structure (XAFS) analysis to clarify the crystal structure of MnN. Single-phase MnN thin films, produced by reactive magnetron sputtering, are characterized using x-ray diffraction (XRD), x-ray absorption near edge structure (XANES), and extended x-ray absorption fine structure (EXAFS). XRD data indicates the successful formation of the MnN phase during the reactive nitrogen sputtering of Mn. By analyzing XANES spectra at the Mn K and L-edges, as well as the N K-edge, and combining the results with EXAFS analysis, this study concludes that MnN crystallizes in the RS structure. The sensitivity of the metal K-edge XANES pre-edge peak to local coordination symmetry is crucial in this determination
Edge States in 2D APbBr Hybrid Perovskites Enabled by Local Structural Reorganization
No full textThe edge states (ES) in two-dimensional (2D) hybrid lead halide perovskites (LHPs) exhibit distinct electronic characteristics, including lower energy and longer lifetimes compared to the interior states (IS). Though the ES of these 2D LHPs show prospect of facilitating photovoltaic and optoelectronic effects, the underlying mechanism remains elusive. Here, the occurrence of ES in a family of 2D APbBr (A = organic amine cation) LHPs is attributed to the Rashba/Dresselhaus (RD) spin splitting induced by local structural reorganization on the crystal edge. The experimental and theoretical characterizations reveal that the local structure on the crystal edge is significantly strained, which leads to considerable out-of-plane distortion of adjacent PbBr octahedra, local loss of inversion symmetry and therefore spin-splitting energy required for the formation of ES. This findings contribute fresh perspectives to the fundamental comprehension of the RD effect, extending the boundaries of spintronics and opening promising pathways for the conceptualization and refinement of devices centered on ES
Tyrosinase Enzyme-Inspired Cu(I)-Porous Organic Polymer for Selective Oxidation of Biomass-Derived 5-HMF
No full textIn biobased PET, terephthalic acid (TPA) can be replaced with biobase alternatives like bioderived 5-diformylfuran (DFF). In this work, we have selectively synthesized DFF from the oxidation of 5-hydroxymethylfurfural (HMF) using our tyrosinase enzyme-inspired catalysts vicinal V-Cu-POP and nonvicinal NV-Cu-POP, respectively. Motivated by the oxygenated form of tyrosinase, we introduced binuclear copper(I) moieties into a porous organic polymer to create enzyme-inspired heterogeneous catalysts for the selective oxidation of HMF. V-Cu-POP can effectively activate O for mild and selective oxidation because the two Cu centers are in close proximity, which is impossible in the case of NV-Cu-POP. For the determination of the coordination environment of the catalytically active site, the X-ray absorption near-edge structure (XANES) studies and the copper(I) state for both the enzyme-inspired catalysts V-Cu-POP and NV-Cu-POP are identified through characteristic features in the absorption spectra. The fitting parameters and EXAFS spectra rule out the formation of the Cu–Cu bond. Further, the key intermediate μ-hydroxy species (Cu (II)–O–O–Cu (II)), which forms during the reaction in the case of the enzyme-inspired catalyst, V-Cu-POP is also confirmed by time-resolved in situ ATR-IR spectroscopy and DFT computational study. This intermediate is not formed in the case of nonvicinal NV-Cu-POP, which is the main reason for lower catalytic activity toward HMF oxidation. NV-Cu-POP still retains the peaks of reactants at the same reaction conditions, which is confirmed by time-resolved in situ ATR-IR spectroscopy. Overall, in this study, we have shown how a tyrosinase enzyme-inspired catalyst exhibits greater catalytic activity toward the oxidation reaction due to the formation of its vicinal conformer compared to the nonvicinal conformer