Anomalous thermal broadening in the Shastry-Sutherland model and SrCu2(_2(BO3)2_3)_2

5 pages, 5 figuresInternational audienceIn the quantum magnet SrCu$_2$⁢(BO$_3$)$_2$, an anomalous thermal broadening of the triplon modes has been measured at relatively low temperatures compared to the triplon gap $\Delta$ using both inelastic neutron scattering and Raman spectroscopy. Given how accurately a broad variety of physical phenomena inSrCu$_2$⁢(BO$_3$)$_2$ are captured by the spin $S=1/2$ Shastry-Sutherland model, it remains an open question whether the anomalous thermal broadening is also an intrinsic feature of this minimal model. However, few techniques are available for computing the finite-temperature dynamics of strongly interacting many-body systems. To address this problem, we have developed a broadly applicable numerical simulation method based on matrix-product states to simulate dynamical spectral functions at nonzero temperatures accurately, detailed in a companion paper [Phys. Rev. B 113, 024406 (2026)]. Using this technique, we demonstrate that the experimentally observed broadening is captured by the Shastry-Sutherland model. Perturbative calculations identify the origin of this phenomenon as singlet bound two-triplon states being thermally excited at an energy scale small compared to the gap $\Delta$ to the single triplon excitations at the experimentally relevant model parameters

Measurements of the inclusive W and Z boson production cross sections and their ratios in proton-proton collisions at s\sqrt{s} = 13.6 TeV

International audienceMeasurements are presented of the W and Z boson production cross sections in proton-proton collisions at a center-of-mass energy of 13.6 TeV. Data collected in 2022 and corresponding to an integrated luminosity of 5.01 fb$^{-1}$ with one or two identified muons in the final state are analyzed. The results for the products of total inclusive cross sections and branching fractions for muonic decays of W and Z bosons are 11.93 $\pm$ 0.08 (syst) $\pm$ 0.17 (lumi) $^{+0.07}_{-0.07}$ (acc) nb for W$^+$ boson production, 8.86 $\pm$ 0.06 (syst) $\pm$ 0.12 (lumi) $^{+0.05}_{-0.06}$ (acc) nb for W$^-$ boson production, and 2.021 $\pm$ 0.009 (syst) $\pm$ 0.028 (lumi) $^{+0.011}_{-0.013}$ (acc) nb for the Z boson production in the dimuon mass range of 60-120 GeV, all with negligible statistical uncertainties. Furthermore, the corresponding fiducial cross sections, as well as cross section ratios for both fiducial and total phase space, are provided. The ratios include charge-separated results for W boson production (W$^+$ and W$^-$) and the sum of the two contributions (W$^\pm$), each relative to the measured Z boson production cross section. Additionally, the ratio of the measured cross sections for W$^+$ and W$^-$ boson production is reported. All measurements are in agreement with theoretical predictions, calculated at next-to-next-to-leading order accuracy in quantum chromodynamics

Characterization of the Electronic Noise in the Readout of Resistive Micromegas in the High-Angle Time Projection Chambers of the T2K Experiment

International audienceThe two high-angle Time Projection Chambers of the T2K experiment are equipped with a new readout system based on resistive Micromegas detector technology, and utilize custom-made electronics based on AFTER chips for signal processing. This study analyzes and characterizes the electronic noise of the detector readout chain to develop a comprehensive noise model. The model enables the generation of Monte Carlo simulations to investigate systematic effects in signal processing. The analysis is based on data collected from 32 resistive Micromegas detectors, recorded without zero suppression. All detectors exhibit a quasi-identical and time-stable noise level. The developed analytical model accurately describes the observed noise, and derived Monte Carlo simulations show excellent agreement with experimental data

Evidence of radiation induced segregation clustering in binary ferritic model alloys

International audienceThis study investigates the microstructural changes and hardening mechanisms in irradiated binary Fe-Mn and Fe-Ni model alloys using atom probe tomography (APT). Mn and Ni are key alloying elements in reactor pressure vessel (RPV) steels, enhancing hardenability and mechanical properties while increasing irradiation sensitivity. Neutron irradiation introduces point defects that lead to solute clustering, impacting the mechanical properties of the materials. APT analysis reveals and quantifies the formation of Mn and Ni clusters, which act as barriers to dislocation motion and contribute to irradiation hardening. This research isolates the individual behavior of Mn and Ni by studying undersaturated binary model alloys, providing detailed insights into the mechanisms of radiation-induced segregation and nanoscale solute clustering and these effect on hardenin

Microstructure optimization by combinatorial approach applied to Duplex Medium Manganese steels

International audienceThis study introduces a novel combinatorial approach for optimizing the microstructure of duplex medium-manganese (Mn) steels by coupling a controlled thermal gradient with in situ high-energy X-ray diffraction (HEXRD) during intercritical annealing. A temperature gradient (680–720 °C) across a single sample enables real-time monitoring of phase transformations over a broad thermal range in one experiment. Compared to isothermal trials, this method offers high-resolution insight into austenite formation kinetics and phase stability, enabling accurate identification of the optimal temperature window for maximizing retained austenite. The results reveal a narrow optimal range (∼700–710 °C) where retained austenite fractions exceed 30 %, surpassing values from traditional methods. Post-mortem Electron Backscatter Diffraction (EBSD) analysis showed the spatial distribution of stabilized austenite, highlighting the complementary roles of in situ and ex situ characterization. This work demonstrates the potential of gradient-based combinatorial metallurgy to accelerate process optimization and support the design of high-performance third-generation advanced high-strength steels

Simulation of shockless spalling fragmentation using the Discrete Element Method (DEM)

International audienceIn the present study a Discrete Element Method (DEM) is considered to model the dynamic behaviour and fragmentation mechanisms of alumina ceramic under high strain-rate shockless loading. GEPI (high-pulsed power) spalling experiments are simulated. The DEM allows to take into account the accurate propagation and interaction of stress waves within the samples upon calibration of microscopic bond parameters. The results indicate that a standard failure criterion can effectively represent the spalling phenomenon, though discrepancies with experimental data increase at higher strain rates. To address this, the study combines the DEM approach with a damage law, specifically the first and second order Kachanov damage law, tomodel crack initiation and propagation. Comparative analysis with experimental rear face velocity profiles validates the approach. The strain-rate sensitivity of the present DEM model is explored using loading pulses of increasing intensity that induce different strain-rate levels. This research demonstrates that the DEM approach can effectively model dynamic behaviour in brittle solids leading to a multiple fragmentation sensitive to the strain rate

Integrability and lattice discretizations of all Topological Defect Lines in minimal CFTs

International audienceWe discuss in this paper the lattice discretizations of all topological defect lines (TDLs) for diagonal, minimal CFTs, using integrable restricted solid-on-solid (RSOS) models. For these CFTs, the TDLs can be labeled by the Kac labels. In the case of $(1,s)$ TDLs, lines that are exactly topological on the lattice can be obtained using the centralizer of the underlying Temperley-Lieb algebra, all the other lines become topological in the continuum limit only. Our general construction relies on insertions of rows/columns of faces with modified spectral parameters, and can therefore be studied using integrability techniques. We determine the regions of spectral parameters realizing the different $(r,s)$ TDLs, and in particular calculate analytically all the associated eigenvalues (and degeneracy factors). We also show how fusion of TDLs can be obtained from fusion hierarchies in the algebraic approach to the Bethe-ansatz. All our results are checked numerically in detail for several minimal CFTs

Ti and Ni-based BEOL CMOS-compatible P+-InGaAs ohmic contacts for the future of wireless communications

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Exploring the structural evolution of the NdFeB magnets with various carbon contamination in the PIM process

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Field-induced states and thermodynamics of the frustrated Heisenberg antiferromagnet on a square lattice

We investigate the ground-state and finite-temperature properties of the $J_1$-$J_2$ Heisenberg antiferromagnet on the square lattice in the presence of an external magnetic field. We focus on the highly frustrated regime around $J_2 \approx J_1/2$. The $h$-$T$ phase diagram is investigated with particular emphasis on the finite-temperature transition into the "up-up-up-down" state that is stabilized by thermal and quantum fluctuations and manifests itself as a plateau at one half of the saturation magnetization in the quantum case. We also discuss the enhanced magnetocaloric effect associated to the ground-state degeneracy that arises at the saturation field for $J_2=J_1/2$. For reference, we first study the classical case by classical Monte Carlo simulations. Then we turn to the extreme quantum limit of spin-1/2 where we perform zero- and finite-temperature Lanczos calculations