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NNLOCAL: completely local subtractions for color-singlet production in hadron collisions
No full textWe present NNLOCAL, a proof-of-concept parton-level Monte Carlo program implementing the extension of the completely local subtraction scheme CoLoRFulNNLO to the case of color-singlet production in hadron collisions. We have built general local subtraction terms that regularize all single and double unresolved infrared singularities in real radiation phase space. The subtractions are then integrated fully analytically to the required order in the parameter of dimensional regularization. Combining the integrated counterterms with the virtual contributions we demonstrate the cancellation of all infrared poles explicitly. We validate our procedure by computing the fully differential cross section for the production of a Higgs boson at the LHC in an effective field theory with gluons only. Our code provides the first public implementation of a completely local analytic subtraction scheme at next-to-next-to-leading order accuracy
Supramolecular Engineering of Narrow Absorption Bands by Exciton Coupling in Pristine and Mixed Solid-State Dye Aggregates
No full textTunability of functional properties in a continuous manner is desired but challenging to accomplish for organic solid-state materials. Herein, we describe a method for tuning optoelectronic properties of solid-state aggregates with narrow absorption bands. First, we systematically shift the absorption maxima of highly dipolar merocyanine dyes in solution by chemical alterations of their chromophore cores. This leaves their solid-state packing arrangements unchanged, affording similar J- and H-coupled aggregate absorption bands at different wavelengths. Next, mixing these isostructural dyes leads to a spectral fine-tuning of the mixed layers, which could be characterized as crystalline organic solid solutions and utilized in narrowband color-selective organic photodiodes. Finally, we devise a semiempirical model, which explains the observed spectral tuning in terms of the molecular exciton theory. Thus, we demonstrate narrowband absorbing solid-state aggregates spanning the wavelength range of 437–760 nm, whose absorption can be fine-tuned over 40% of the visible light range
Test of lepton flavor universality in semileptonic B meson decays in proton-proton collisions at = 13 TeV
No full textA measurement of the ratio of branching fractions (J/) = (B J/)/(B J/) in the J/, decay channel is presented. This measurement uses a sample of proton-proton collision data collected at a center-of-mass energy of 13 TeV by the CMS experiment in 2018, corresponding to an integrated luminosity of 59.7 fb. The measured ratio, (J/) = 0.17 (stat) (syst) (theo) = 0.17 0.33, agrees with the value of 0.2582 0.0038 predicted by the standard model, which assumes lepton flavor universality
Search for high-mass resonances in a final state comprising a gluon and two hadronically decaying W bosons in proton-proton collisions at = 13 TeV
No full textA search for high-mass resonances decaying into a gluon, g, and two W bosons is presented. A Kaluza-Klein gluon, g, decaying in cascade via a scalar radion R, g → gR → gWW, is considered. The final state studied consists of three large-radius jets, two of which contain the products of hadronically decaying W bosons, and the third one the hadronization products of the gluon. The analysis is performed using proton-proton collision data at = 13 TeV collected by the CMS experiment at the CERN LHC during 2016–2018, corresponding to an integrated luminosity of 138 fb. The masses of the g and R candidates are reconstructed as trijet and dijet masses, respectively. These are used for event categorization and signal extraction. No excess of data events above the standard model background expectation is observed. Upper limits are set on the product of the g production cross section and its branching fraction via a radion R to gWW. This is the first analysis examining the resonant WW+jet signature and setting limits on the two resonance masses in an extended warped extra-dimensional model.[graphic not available: see fulltext
The effect of PTFE on the deformation behavior of PPS composites for high-pressure hydrogen applications
No full textEfficient storage of hydrogen is crucial for the widespread adoption of renewable energy. Reciprocatingpiston compressors, featuring advanced sealing solutions, are essential to meet the stringent demands ofnon-lubricated hydrogen applications, ensuring gas purity and high pressure differentials. Polyphenylenesulfide polymer matrix composites exhibit high mechanical strength and low friction and wear, making themvaluable in tribological applications. This study investigates carbon fiber reinforced polyphenylene sulfidemodifications with different PTFE contents by employing advanced imaging techniques to assess the effect ofdry-lubricant on properties with respect to application in high-pressure reciprocating compressors. Thermo-mechanical and tribological testing, along with microstructure analysis utilizing synchrotron tomography,presents the importance of dry lubricating PTFE additives. Furthermore, the research provides insightsinto the micromechanical deformation behavior of short fiber reinforced polymers and identifies promisingcompositions suitable for advanced hydrogen compression
Spin polarization of the two-dimensional electron gas at the EuO/SrTiO (001) interface
No full textSpin-polarized two-dimensional electron gases (2DEGs) are of particular interest for functional oxide electronics applications. The redox-created 2DEG residing on the strontium titanate, SrTiO3 (STO), side of a europium monoxide (EuO)/SrTiO3 (001) interface is expected to be significantly spin polarized due to the proximity to the strong (7/..) Heisenberg ferromagnet EuO. We apply magnetic circular dichroism in the angular distribution (MCDAD) of photoemitted electrons to investigate whether and how the induced spin polarization of the 2DEG depends on the dimensionality of the overlaying EuO layer. The experimental data are complemented by density functional theory calculations with a Hubbard term (DFT+). We show that the EuO/STO interfacial 2DEG is spin polarized even for ultrathin EuO overlayers, starting at an EuO threshold thickness of only two monolayers. Additional EuO monolayers even increase the induced magnetic Ti moment and thus the spin polarization of the 2DEG. Our results and the potential to enhance the magnetic order of EuO by other proximity effects indicate that the EuO/STO(001) interface is an ideal template for creating (multi-)functional spin-polarized 2DEGs for application in oxide electronics
Search for vector-like leptons coupling to first- and second-generation Standard Model leptons in pp collisions at = 13 TeV with the ATLAS detector
No full textA search for pair production of vector-like leptons coupling to first- and second-generation Standard Model leptons is presented. The search is based on a dataset of proton-proton collisions at = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 140 fb. Events are categorised depending on the flavour and multiplicity of leptons (electrons or muons), as well as on the scores of a deep neural network targeting particular signal topologies according to the decay modes of the vector-like leptons. In each of the signal regions, the scalar sum of the transverse momentum of the leptons and the missing transverse momentum is analysed. The main background processes are estimated using dedicated control regions in a simultaneous fit with the signal regions to data. No significant excess above the Standard Model background expectation is observed and limits are set at 95% confidence level on the production cross-sections of vector-like electrons and muons as a function of the vector-like lepton mass, separately for SU(2) doublet and singlet scenarios. The resulting mass lower limits are 1220 GeV (1270 GeV) and 320 GeV (400 GeV) for vector-like electrons (muons) in the doublet and singlet scenarios, respectively.[graphic not available: see fulltext
Attosecond Inner-Shell Lasing at Angstrom Wavelengths
No full textSince the invention of the laser nonlinear effects such as filamentation, Rabi-cycling and collective emission have been explored in the optical regime leading to a wide range of scientific and industrial applications. X-ray free electron lasers (XFELs) have led to the extension of many optical techniques to X-rays for their advantages of angstrom scale spatial resolution and elemental specificity. One such example is XFEL driven population inversion of 1s core hole states resulting in inner-shell K (2p to 1s) X-ray lasing in elements ranging from neon to copper, which has been utilized for nonlinear spectroscopy and development of next generation X-ray laser sources. Here we show that strong lasing effects, similar to those observed in the optical regime, can occur at 1.5 to 2.1 angstrom wavelengths during high intensity (> W/cm) XFEL driven inner-shell lasing and superfluorescence of copper and manganese. Depending on the temporal substructure of the XFEL pump pulses(containing - photons) i, the resulting inner-shell X-ray laser pulses can exhibit strong spatial inhomogeneities as well as spectral splitting, inhomogeneities and broadening. Through 3D Maxwell Bloch theory we show that the observed spatial inhomogeneities result from X-ray filamentation, and that the spectral splitting and broadening is driven by Rabi cycling with sub-femtosecond periods. Our simulations indicate that these X-ray pulses can have pulse lengths of less than 100 attoseconds and coherence properties that open the door for quantum X-ray optics applications
PolarX-EBIT – a versatile tool for X-ray resonant spectroscopy
No full textResonant photo-excitation provides a direct tool for investigating electronic transitions in atoms and ions. By combining EBITs and ultrabrilliant x-ray sources this kind of spectroscopy became also available for highly charged ions. Here we present the PolarX-EBIT, a compact permanent magnet EBIT built by the Max-Planck-Institute for Nuclear Physics and University Jena specifically for operation at synchrotron radiation light source facilities. It employs a novel off-axis electron gun, allowing the photon beam to pass through the trap and be made available for downstream setups. Additionally, it features fast-switching power supplies for charge breeding and background reduction schemes, a time-of-flight ion extraction beamline and large area SDD detectors. Multiple successful experiments have been performed in the soft and hard x-ray regimes at the light sources BESSY II and PETRA III, measuring transition energies, oscillator strengths, natural line widths, photoionization and population balance. Furthermore, narrow lines of He-like ions have also been used as a diagnostic tool for the spectral performance of the photon beamlines
Structural basis of ubiquitin ligase Nedd4-2 autoinhibition and regulation by calcium and 14-3-3 proteins
No full textNedd4-2 E3 ligase regulates Na+ homeostasis by ubiquitinating various channels and membrane transporters, including the epithelial sodium channel ENaC. In turn, Nedd4-2 dysregulation leads to various conditions, including electrolytic imbalance, respiratory distress, hypertension, and kidney diseases. However, Nedd4-2 regulation remains mostly unclear. The present study aims at elucidating Nedd4-2 regulation by structurally characterizing Nedd4-2 and its complexes using several biophysical techniques. Our cryo-EM reconstruction shows that the C2 domain blocks the E2-binding surface of the HECT domain. This blockage, ubiquitin-binding exosite masking by the WW1 domain, catalytic C922 blockage and HECT domain stabilization provide the structural basis for Nedd4-2 autoinhibition. Furthermore, Ca2+-dependent C2 membrane binding disrupts C2/HECT interactions, but not Ca2+ alone, whereas 14-3-3 protein binds to a flexible region of Nedd4-2 containing the WW2 and WW3 domains, thereby inhibiting its catalytic activity and membrane binding. Overall, our data provide key mechanistic insights into Nedd4-2 regulation toward fostering the development of strategies targeting Nedd4-2 function