34 Search Results

Using $20.3{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collision data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector operating at the BEPCII collider, the branching fractions of three hadronic charm meson decays, $D^{+}\to \varphi {\pi }^{+}{\pi }^{+}{\pi }^{-}$ , $D^{+}\to K_S^0{K}^{+more »}$ π + π − π 0 , and $D^{+}\to K_S^0{K}^{+}\omega$ , are measured for the first time to be $(0.54\pm 0.19\pm 0.02)\times {10}^{-4}$ , $(2.51\pm 0.34\pm 0.14)\times {10}^{-4}$ , and $(2.02\pm 0.35\pm 0.10)\times {10}^{-4}$ , respectively. Futhermore, the branching fractions of $D^{+}\to K^{+}{K}^{-}{\pi }^{+}{\pi }^{+}{\pi }^{-}$ and $D^{+}\to K_S^0{K}^{+}\eta$ are measured with improved precision, yielding values of $(0.66\pm 0.11\pm 0.03)\times {10}^{-4}$ and $(2.27\pm 0.22\pm 0.05)\times {10}^{-4}$ , respectively. Published by the American Physical Society 2025« less

Using a dataset of $(27.12\pm 0.14)\times {10}^8\psi \left(3686\right)$ events collected by the BESIII detector operating at the BEPCII collider, we report the first observation of the decay $\psi \left(3686\right)\to {\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0\omega$ with a statistical significance of $8.9\sigma$ . The measured branching fraction is $(1.24\pm 0.16_{\mathrm{stat}}\pm 0.11_{\mathrm{sys}})\times {10}^{more »}$ − 5 , where the first uncertainty is statistical and the second is systematic. Additionally, we investigate potential intermediate states in the invariant mass distributions of ${\mathrm{\Sigma }}^0\omega$ , ${\overline{\mathrm{\Sigma }}}^0\omega$ and ${\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0$ . A hint of a resonance is observed in the invariant mass distribution of $M_{{\mathrm{\Sigma }}^0\left({\overline{\mathrm{\Sigma }}}^0\right)\omega }$ , located around $2.06\mathrm{GeV}/c^2$ , with a significance of $2.5\sigma$ . Published by the American Physical Society 2025« less

Using $(2712.4\pm 14.3)\times {10}^6\psi \left(3686\right)$ events collected with the BESIII detector at the BEPCII collider, the decay ${\eta }_c\to \gamma \gamma$ in $J/\psi \to \gamma {\eta }_c$ is observed. We determine the product branching fraction $\mathcal{B}(J/\psi \to \gamma {\eta }_c)\times \mathcal{B}more »$ ( η c → γ γ ) = ( 5.23 ± 0.2 6 stat ± 0.3 0 syst ) × 10 − 6 . This result is consistent with the lattice QCD calculation $(5.34\pm 0.16)\times {10}^{-6}$ from HPQCD in 2023. By using the world-average values of $\mathcal{B}(J/\psi \to \gamma {\eta }_c)$ and the total decay width of ${\eta }_c$ , the partial decay width $\mathrm{\Gamma }({\eta }_c\to \gamma \gamma )$ is determined to be $(11.30\pm 0.56_{\mathrm{stat}}\pm 0.66_{\mathrm{syst}}\pm 1.14_{\mathrm{ref}})\mathrm{keV}$ , which deviates from the corresponding world-average value by $3.4\sigma$ . Published by the American Physical Society 2025« less

Context. The nearby elliptical galaxy M87 contains one of only two supermassive black holes whose emission surrounding the event horizon has been imaged by the Event Horizon Telescope (EHT). In 2018, more than two dozen multi-wavelength (MWL) facilities (from radio to γ-ray energies) took part in the second M87 EHT campaign.Aims. The goal of this extensive MWL campaign was to better understand the physics of the accreting black hole M87*, the relationship between the inflow and inner jets, and the high-energy particle acceleration. Understanding the complex astrophysics is also a necessary first step towards performing further tests of general relativity.Methods.more » The MWL campaign took place in April 2018, overlapping with the EHT M87* observations. We present a new, contemporaneous spectral energy distribution (SED) ranging from radio to very high-energy (VHE) γ-rays as well as details of the individual observations and light curves. We also conducted phenomenological modelling to investigate the basic source properties.Results. We present the first VHE γ-ray flare from M87 detected since 2010. The flux above 350 GeV more than doubled within a period of ≈36 hours. We find that the X-ray flux is enhanced by about a factor of two compared to 2017, while the radio and millimetre core fluxes are consistent between 2017 and 2018. We detect evidence for a monotonically increasing jet position angle that corresponds to variations in the bright spot of the EHT image.Conclusions. Our results show the value of continued MWL monitoring together with precision imaging for addressing the origins of high-energy particle acceleration. While we cannot currently pinpoint the precise location where such acceleration takes place, the new VHE γ-ray flare already presents a challenge to simple one-zone leptonic emission model approaches, and it emphasises the need for combined image and spectral modelling.Key words: galaxies: active / galaxies: individual: M 87 / galaxies: jets / galaxies: nuclei‡ NASA Hubble Fellowship Program, Einstein Fellow.« less

Interlayer van der Waals (vdW) coupling is generic in two-dimensional materials such as graphene and transition-metal dichalcogenides, which can induce very low-energy phonon modes. Using high-resolution inelastic hard x-ray scattering, we uncover the ultralow energy phonon mode along the Cu-O bond direction in the high-T_c cuprate (Bi,Pb)₂(Sr,La)₂⁢CuO_6+$$\delta$$ (Bi2201). The energy and full-width half-maximum (FWHM) of these modes are independent of temperature, while their intensity decreases with doping in accordance with an increasing c-axis lattice parameter. Here, we compare the experimental results to first-principles density functional theory simulations and identify the observed mode as a van der Waals phonon, which arisesmore » from the shear motion of the adjacent Bi-O layers. This shows that Bi-based cuprate has vibrational properties similar to graphene and transition-metal dichalcogenides, which can be exploited to engineer novel heterostructures.« less

The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector.

X-ray tomography is widely used for three-dimensional structure determination in many areas of science, from the millimeter to the nanometer scale. The resolution and quality of the 3D reconstruction is limited by the availability of alignment parameters that correct for the mechanical shifts of the sample or sample stage for the images that constitute a scan. In this paper we describe an algorithm for marker-free, fully automated and accurately aligned and reconstructed X-ray tomography data. Our approach solves the tomographic reconstruction jointly with projection data alignment based on a rigid-body deformation model. We demonstrate the robustness of our method onmore » both synthetic phantom and experimental data and show that our method is highly efficient in recovering relatively large alignment errors without prior knowledge of a low resolution approximation of the 3D structure or a reasonable estimate of alignment parameters.« less

Flip-chip architectures have recently enabled significant scaling-up of multi-qubit circuits and have been used to assemble hybrid quantum systems that combine different substrates, for example, for quantum acoustics experiments. The standard flip-chip method uses superconducting galvanic connections between two substrates, typically implemented using sophisticated indium wafer-bonding systems, which give highly reliable and temperature-cyclable assemblies, but are expensive, somewhat inflexible in design, and require robust substrates that can sustain the large compressive forces required to cold-weld the indium bonds. A much simpler method is to assemble dies using very low-force contacts and air-dried adhesives, although this does not provide a galvanicmore » contact between the dies. In this work, we demonstrate that the latter technique can be used to reliably couple superconducting qubit circuits, in which the qubits are on separate dies, without the need for a galvanic connection. We demonstrate full vector qubit control of each qubit on each of the two dies, with high-fidelity single-shot readout, and further demonstrate entanglement-generating excitation swaps as well as benchmark a controlled-Z entangling gate between the two qubits on the two dies. This exemplifies a simple and inexpensive assembly method for two-plus-one-dimensional quantum circuit integration that supports the use of delicate or unusually shaped substrates.« less

Resolving chemical species at the nanoscale is of paramount importance to many scientific and technological developments across a broad spectrum of disciplines. Hard x-rays with excellent penetration power and high chemical sensitivity are suitable for speciation of heterogeneous (thick) materials. Here, we report nanoscale chemical speciation by combining scanning nanoprobe and fluorescence-yield x-ray absorption near-edge structure (nano-XANES). First, the resolving power of nano-XANES was demonstrated by mapping Fe(0) and Fe(III) states of a reference sample composed of stainless steel and hematite nanoparticles with 50-nm scanning steps. Nano-XANES was then used to study the trace secondary phases in lithium iron phosphatemore » (LFP) particles. We observed individual Fe-phosphide nanoparticles in pristine LFP, whereas partially (de)lithiated particles showed Fe-phosphide nanonetworks. These findings shed light on the contradictory reports on Fe-phosphide morphology in the literature. Nano-XANES bridges the capability gap of spectromicroscopy methods and provides exciting research opportunities across multiple disciplines.« less