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Deconvolution of superimposing reaction signals from DSC curves in selected Al-Mg-Si-(Cu) alloys by mean-field modeling and HEXRD
No full textThe present work describes a systematic approach to improve mean-field simulations of dissolution and precipitation of precipitates from the late stages in the precipitation sequence in AlMgSiCu alloys for processing simulations. In addition to metastable precipitates, it considers the evolution of two populations (coarse and fine) of the thermodynamically stable phases in EN AW-6061 and EN AW-6016, β-Mg2Si and Si respectively. The setup is based on two previous publications using heterogeneous nucleation site energies and their distribution. The simulations are calibrated using data from continuous cooling and heating experiments obtained with differential scanning calorimetry (DSC) and high-energy X-ray diffraction (HEXRD). We show that mean-field simulations combined with DSC and HEXRD can provide valuable information to eliminate uncertainties related to, for instance, the thermodynamic description of metastable precipitates. The method described in this paper also delivers very reasonable results for the evolution of the individual phase fractions. It potentially facilitates the assessment of the influence of different types of nucleation sites and their densities
Combination of searches for heavy vector boson resonances in proton-proton collisions at = 13 TeV
No full textA combined statistical analysis of searches for heavy vector boson resonances decaying into pairs of W, Z, or Higgs bosons, as well as into quark pairs (, , , ) or lepton pairs (, ), with e, , , is presented. The results are based on proton-proton collision data at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb, collected by the CMS experiment from 2016 to 2018. No significant deviation from the expectations of the standard model is observed. The results are interpreted in the simplified heavy vector triplet (HVT) framework, setting 95% confidence level upper limits on the production cross sections and coupling strengths to standard model particles or the HVT bosons. The results exclude HVT resonances with masses below 5.5 TeV in a weakly coupled scenario, below 4.8 TeV in a strongly coupled scenario, and up to 2.0 TeV in the case of production via vector boson fusion. The combination provides the most stringent constraints to date on new phenomena predicted by the HVT model
Strategy and performance of the CMS long-lived particle trigger program in proton-proton collisions at = 13.6 TeV
No full textIn the physics program of the CMS experiment during the CERN LHC Run 3, which started in 2022, the long-lived particle triggers have been improved and extended to expand the scope of the corresponding searches. These dedicated triggers and their performance are described in this paper, using several theoretical benchmark models that extend the standard model of particle physics. The results are based on proton-proton collision data collected with the CMS detector during 20222024 at a center-of-mass energy of 13.6 TeV, corresponding to integrated luminosities of up to 123 fb
Search for heavy resonances decaying into two Higgs bosons in the final state in proton-proton collisions at = 13 TeV
No full textA search is presented for massive narrow-width resonances in the mass range of 14.5 TeV, decaying into pairs of Higgs bosons (HH). The search uses proton-proton collision data at a center-of-mass energy of 13 TeV collected with the CMS detector at the CERN LHC during 20162018, corresponding to an integrated luminosity of 138 fb. The analysis targets final states where one Higgs boson decays into a pair of bottom quarks and the other into a pair of tau leptons, X HH . It uses a single large jet to reconstruct the H decay, while the H decay products can either be contained within a single large jet or appear as two isolated tau leptons. The observed data are consistent with standard model background expectations. Upper limits at 95% confidence level are set on the production cross section for resonant HH production for masses between 1 and 4.5 TeV. This analysis sets the most sensitive limits to date on X HH decays in the mass range of 1.4 to 4.5 TeV
Search for heavy scalar resonances decaying to Lorentz-boosted Higgs and Higgs-like bosons in the 4q final state at = 13 TeV
No full textA search is performed for a heavy scalar resonance X decaying to a Higgs boson (H) and a Higgs-like scalar boson (Y) in the two bottom quark (H ) and four quark (Y VV 4q) final state, where V denotes a W or Z boson. Masses of the X between 900 and 4000 GeV and the Y between 60 and 2800 GeV are considered. The search is performed in data collected by the CMS experiment at the CERN LHC from proton-proton collisions at 13 TeV center-of-mass energy, with a data set corresponding to a total integrated luminosity of 138 fb. It targets the Lorentz-boosted regime, in which the products of the H decay can be reconstructed as a single large-area jet, and those from the Y VV 4q decay as either one Y 4q or two V to jets. Jet identification and mass reconstruction exploit machine-learning tools, including a novel attention-based 'particle transformer' for Y 4q identification. No significant excess is observed in the data above the standard model background expectation. Upper limits on the product of production cross section and branching fraction as low as 0.2 fb are derived at 95% confidence level for various mass hypotheses. This is the first search at the LHC for scalar resonances in the all-hadronic VV decay channel
FLAG review 2024
No full textWe review lattice results related to pion, kaon, D-meson, B-meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. More specifically, we report on the determination of the light-quark masses, the form factor f+(0) arising in the semileptonic K→π transition at zero momentum transfer, as well as the decay-constant ratio fK/fπ and its consequences for the Cabibbo–Kobayashi–Maskawa (CKM) matrix elements Vus and Vud. We review the determination of the BK parameter of neutral kaon mixing as well as the additional four B parameters that arise in theories of physics beyond the Standard Model. For the heavy-quark sector, we provide results for mc and mb as well as those for the decay constants, form factors, and mixing parameters of charmed and bottom mesons and baryons. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. We review the status of lattice determinations of the strong coupling constant αs. We review the determinations of nucleon charges from the matrix elements of both isovector and flavor-diagonal axial, scalar and tensor local quark bilinears, and momentum fraction, helicity moment and the transversity moment from one-link quark bilinears. We also review determinations of scale-setting quantities. Finally, in this review we have added a new section on the general definition of the low-energy limit of the Standard Model
Effect of particle reinforcements on the texture and dislocation activities of magnesium matrix composites
No full textThe introduction of ceramic particles into magnesium (Mg) alloys not only leads to a grain refinement effect but also influences their texture. However, dislocation activities within the Mg matrix resulting from these effects remain unclear. In this study, in-situ tensile testing combined with synchrotron radiation techniques was utilized to investigate the microstructure, load partitioning, and dislocation density evolution of SiCp/Mg–5Zn and Mg–5Zn samples under different tensile strain conditions. It was found that more dislocation slip systems were involved in the SiCp/Mg–5Zn composite during deformation, whereas the Mg–5Zn alloy exhibited a higher capacity for dislocation accumulation. By an elasto-plastic self-consistent (EPSC) model and a full-field crystal plasticity finite element method (CPFEM) simulation, the pyramidal dislocation activity was identified after a 2 % strain in the SiCp/Mg–5Zn composite. This was accompanied by the load transfer between α-Mg grains as well as regions with different SiCp volume fractions. Additionally, a novel texture formation mechanism was proposed to explain the texture characteristics of Mg matrix composites (MMCs). The strengthening mechanisms induced by reinforcements were also quantified
Precipitation and reverted austenite formation in maraging 350 steel: Competition or cooperation?
No full textAged maraging steels offer unique strength and toughness via the presence of finely dispersed precipitates, allowing the material to reach values of up to 2400 MPa in yield strength in the case of 18Ni350. However, when aging heat treatments above 550 °C are conducted, simultaneous precipitation and austenite reversion can occur changing the mechanical behavior of the material. Although many studies related to the physical metallurgy of maraging steels have already been published, less attention has been given to a detailed understanding of the initial formation of austenite and its relationship with the precipitates. In this study, undeformed and cold rolled commercial 18Ni350 maraging steel samples were submitted to short aging heat treatments of 1800s at 600, 650, and 700 °C. The influence of the initial microstructure on subsequent phase evolution was studied using in-situ synchrotron X-ray diffraction and final microstructural products using transmission electron microscopy and atom probe tomography. Results show that cold rolled samples did not present faster kinetics of transformation of reverted austenite as expected, but this condition presented austenite in a different morphology than the undeformed condition. However, cold rolling changed the morphology of reverted austenite from elongated (undeformed case) to equiaxed; and induced a higher density of smaller Ni3Ti and Fe2Mo precipitates, especially after low-temperature aging. Besides, the deformation extinguished retained austenite, which influenced the reverted austenite formation, concluding that the simple increase in dislocation density is not a unique and direct factor to increase the reverted austenite kinetics
Evolution of microstructure during tension in a Mg–Ca–Y–Zn–Mn alloy processed by rapidly solidified ribbon consolidation as revealed by in situ synchrotron X-ray diffraction
No full textThe tensile performance of a novel dilute Mg-Ca-Y-Zn-Mn alloy processed by rapidly solidified ribbon consolidation (RSRC) technique was investigated in situ by X-ray diffraction using synchrotron radiation. Moreover, the same study was performed on specimens annealed at 300 and 400 °C for 2 h after RSRC processing. It was found that annealing at 300 °C had no considerable influence on the microstructure and, thus, on the tensile performance. On the other hand, the heat treatment at 400 °C yielded an increase in the recrystallized material fraction and the average grain size, coarsening of the secondary MgCa phase particles as well as a decrease in the intensity of fiber texture. The latter effect caused twinning during tension which contributed to the increase in strain hardening with increasing strain. Due to the texture, mostly non-basal dislocations developed during tensile testing. The interaction between the dominant prismatic dislocations can result in immobile dislocations, which can contribute to the enhanced hardening observed at higher strains
The Many Lives of a Single Sequence: Functional Plasticity Through Amyloid Polymorphism
No full textAmyloids play critical functional roles in biology, including microbialvirulence, innate immunity, and cellular organization, broadening their traditionalassociation with neurodegenerative and systemic diseases. This chapter explores thestructural and functional plasticity of amyloids, emphasizing how a single proteinsequence can adopt multiple brillar conformations, termed polymorphs, each withdistinct biological outcomes. We synthesise recent high-resolution structural insightsfrom cryo-EM, NMR, and microcrystallography that elucidate the polymorphicbehaviour of amyloids in both pathogenic and functional contexts. Particular focusis placed on bacterial functional amyloids that stabilise bio lms and modulate host-pathogen interactions and on antimicrobial peptides that form reversible brils withcytotoxic or immune-stimulatory functions. We also highlight the emerging para-digm of amyloid–nucleic acid co-assemblies and their role in immune recognition,autoimmunity, and possibly the origin of life. By examining structure-functionrelationships across a broad evolutionary spectrum, we argue that amyloi