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Measurement of decays at Belle II
No full textWe present measurements of decays using of data collected from 2019 to 2022 by the Belle~II experiment at the SuperKEKB asymmetric-energy collider. The data sample contains events. We measure branching fractions () and asymmetries () for both and decays. The difference in asymmetries () and the isospin asymmetry () between these neutral and charged channels are also measured. We obtain the following branching fractions and asymmetries: , , , and . The measured difference in asymmetries is , and the measured isospin asymmetry is . The first uncertainties listed are statistical and the second are systematic. These results are consistent with world-average values and theory predictions
Measurement of branching fraction with a hadronic tagging method at Belle II
No full textWe present a measurement of the branching fraction of decays using collected between 2019 and 2022 with the Belle II detector at the SuperKEKB collider. We reconstruct the accompanying meson using the hadronic tagging method, while candidates are identified in the recoil. We find evidence for decays at 3.0 standard deviations, including systematic uncertainties. The measured branching fraction is
Cretaceous amber of Ecuador unveils new insights into South America’s Gondwanan forests
No full textAmber, a fossilised resin, became widespread during the Barremian ( ~ 122 Ma), marking the onset of the Cretaceous Resinous Interval (125–72 Ma). While common in the Northern Hemisphere, amber containing terrestrial arthropod inclusions had not previously been reported from the Mesozoic of South America. Here, we report the major occurrence of such amber from the early Albian ( ~ 112 Ma) Hollín Formation in Ecuadorian Napo region. Discovered at the Genoveva quarry, the amber is associated with coeval pollen and plant macrofossils deposited in fluvio-lacustrine environments. Geochemical analyses suggest araucariacean trees as the resin source, while palynological and macrofloral data indicate moderately diverse forests and the earliest known angiosperm leaf assemblage from north-western South America. Arthropods (hexapods and arachnids) representing at least six orders are well preserved. These findings provide direct evidence of a humid, resinous forest ecosystem and its arthropod fauna in equatorial Gondwana during the Cretaceous Resinous Interval
Microhydration Dynamics in Molecular Photoswitches: Equilibrium State Reconfiguration in Imine‐Based Architectures
No full textThe functional performance of a molecular photoswitch relies strongly on its ability to undergo structural changes in solution. In this context, microsolvation studies in the gas phase provide access to the conformational panorama of these systems in a size-controlled hydrated environment. Here, we exploit this gas-phase vantage point alongside quantum-chemistry calculations to study the structural properties and microhydration dynamics of camphorquinone imine, a chiral molecule holding the functionality to engage in a motor-like function upon light activation. Using molecular rotational resonance spectroscopy with supersonic jets, we detect and analyze the first- and second-order water complexes of the chiral imine. Our findings reveal that initial hydration steps significantly impact the equilibrium between open (E) and closed (Z) forms, culminating in a reversal of relative stability for the switch states. Despite being captured at rotational temperatures near 1 K, we find that water molecules exhibit notable mobility due to the lack of prominent stabilizing secondary interactions. Additionally, the assignment of a key higher-energy closed (Z) water complex provides insights into the energy required for switching between (E) and (Z) states during collisional cooling. We discuss these effects and rationalize them in terms of molecular forces and internal dynamics governing early solvation
Intracellular protein crystallization in living insect cells
No full textCrystallization of recombinant proteins in living cells is an emerging approach complementing conventional crystallization techniques. Homogeneous microcrystals well suited for serial diffraction experiments at X-ray free-electron lasers and synchrotron sources can be produced in a quasi-native environment, without the need for target protein purification. Several protein structures have already been solved; however, exploiting the full potential of this approach requires a systematic and versatile screening strategy for intracellular crystal growth. Recently, we published InCellCryst, a streamlined pipeline for producing microcrystals within living insect cells. Here, we present the detailed protocol, including optimized target gene expression using a baculovirus vector system, crystal formation, detection, and serial X-ray diffraction directly in the cells. The specific environment within the different cellular compartments acts as a screening parameter to maximize the probability of crystal growth. If successful, diffraction data can be collected 24 days after the start of target gene cloning
Rationalisation of multiple square roots in Feynman integrals
No full textFeynman integrals are very often computed from their differential equations. It is not uncommon that the ε-factorised differential equation contains only dlog-forms with algebraic arguments, where the algebraic part is given by (multiple) square roots. It is well-known that if all square roots are simultaneously rationalisable, the Feynman integrals can be expressed in terms of multiple polylogarithms. This is a sufficient, but not a necessary criterium. In this paper we investigate weaker requirements. We discuss under which conditions we may use different rationalisations in different parts of the calculation. In particular we show that we may use different rationalisations if they correspond to different parameterisations of the same integration path. We present a non-trivial example — the one-loop pentagon function with three adjacent massive external legs involving seven square roots — where this technique can be used to express the result in terms of multiple polylogarithms
Atomic Off-Centering Driven Phonon-Glass Electron-Crystal-like Thermoelectric Transport in Entropy-Stabilized Quinary Telluride
No full textEntropy engineering offers innovative design opportunities for synthesizing new thermoelectric materials by integrating conflicting physical parameters. Optimization of configurational entropy holds the potential to simultaneously reduce the thermal conductivity through inherent disorder and enhance the Seebeck coefficient by symmetrizing the crystal lattice, both of which are crucial to augmenting the thermoelectric performance of a crystalline solid. Here, we synthesized an entropy-stabilized quinary metal telluride single crystal, AgGeSnSbTe4, exhibiting an intriguing phonon-glass electron-crystal (PGEC)-like thermoelectric transport. Synchrotron X-ray pair distribution function (X-PDF) analysis infers that entropy-driven stabilization generates a highly symmetric rock-salt average structure but is accompanied by cation distortion in the local structure, which further enhances with temperature, reminiscent of emphanisis. Local lattice distortion-induced anharmonicity with considerable atomic disorder leads to glass-like lattice thermal conductivity, where the phonon mean free path approaches the interatomic distance. Phonon dispersion analysis corroborates the presence of local symmetry breaking, primarily driven by the off-centering displacement of Ge atoms due to the stereochemical expression of the 4s2 lone pair, which results in local ferroelectric lattice instability. Notably, the glassy thermal conductivity is complemented by good electrical conductivity and a high Seebeck coefficient, enabled through long-range atomic order within the average cubic framework. The realization of the PGEC paradigm results in a promising thermoelectric figure-of-merit (zT) of ∼1.2 at 670 K in the Bridgman-grown AgGeSnSbTe4 crystal
Extensive analysis of -ray periodicity in jetted AGNs from the 4FGL catalogue using Fermi -LAT observations
No full textThe quest to uncover periodic patterns within the -ray emissions of jetted active galactic nuclei (AGNs) has recently emerged as a focal point in astrophysics. One of the primary challenges has been the necessity for prolonged exposures in the -ray energy band. In our investigation, we leverage 12 yr’s worth of observations from the Fermi-LAT to systematically explore periodicity across 1492 jetted AGNs catalogued in 4FGL, representing the largest sample analysed to date. Our analysis involves a robust pipeline employing nine distinct techniques designed to detect potential periodic emissions within their -rays. We note that 24 objects with previous hints of periodicity are deliberately excluded in this work since they were reanalysed in a dedicated paper using a similar methodology. Using this thorough approach, we do not find any evidence for periodic signals in the 1492 jetted AGNs -ray light curves analysed here
High-energy diffuse X-ray scattering at ultra-small-angle grazing incidence for local structure study of single-crystalline thin films
No full textWe present a novel experimental approach employing high-energy X-ray scattering in ultra-small-angle grazing-incidence geometry to investigate local atomic structures in single-crystalline thin films. This non-destructive and non-invasive method overcomes the limitations of conventional moderate-energy grazing-incidence diffraction, achieving both high reciprocal-space resolution and coverage and high surface sensitivity. By leveraging high-energy X-ray diffraction, we enable quantitative analysis of local structures in the model system of ferroelectric PbTiO and dielectric SrTiO superlattices through three-dimensional difference pair distribution function analysis. The approach provides detailed insights into atomic structures in single-crystalline thin films with local order, capturing information on spatial correlations within and across unit cells
Time-resolved soft X-ray methods on solids with the MUSIX endstation ‒ Recent upgrades for geometric flexibility
No full textThe International Conference on Synchrotron Radiation Instrumentation (SRI) is a successful conference series continuing for over 40 years, organised by the community of worldwide synchrotron radiation and X-ray free electron laser facilities. The 15th SRI conference (SRI 2024) will be hosted by Deutsches Elektronen-Synchrotron (DESY) and the European XFEL in Hamburg. The SRI conferences are important for the worldwide community to share key experiences in scientific and technical developments. Having timely access to the latest information and new ideas is of crucial importance for the future development of all light sources, the development of the field as a whole as well as for the economic and political development of participating countries