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Model-independent measurement of - mixing parameters in decays at Belle and Belle II
No full textWe perform a model-independent measurement of the - mixing parameters using samples of -collision data collected by the Belle and Belle II experiments that have integrated luminosities of and , respectively. Approximately neutral mesons are reconstructed in the channel, with the neutral flavor tagged by the charge of the pion in the decay. Assuming charge-parity symmetry, the mixing parameters are measured to be and , where the first uncertainties are statistical and the second systematic. The results are consistent with previous determinations
Search for charged lepton flavor violating Z and Z' boson decays in proton-proton collisions at = 13 TeV
No full textA search for flavor violating decays of the Z boson to charged leptons is performed using data from proton-proton collisions at = 13 TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb. Each of the decays Z e, Z e, and Z is considered. The data are consistent with the backgrounds expected from standard model processes. For the Z e channel the observed (expected) 95% confidence level upper limit on the branching fraction is 1.9 (2.0) 10, which is the most stringent direct limit to date on this process; the corresponding limits for the Z e and Z channels are 13.8 (11.4) 10 and 12.0 (5.3) 10, respectively. Additionally, the e final state is used to search for lepton flavor violating decays of Z' resonances in the mass range from 110 to 500 GeV. No significant excess is observed above the predicted background levels
Annular x-ray optics offer improved resolution for radiation sensitive samples
No full textTo detect faint signals from weakly scattering samples, high-resolution x-ray microscopy typically requires a high photon flux. This exposes samples to high radiation doses and can cause radiation damage. In this work we propose the use of annular optics in scanning microscopy as an alternative to full-aperture optics. Annular optics act as high-pass filters that produce a stronger signal from edges. Compared to regular optics with the same numerical aperture, annular optics expose the sample to less dose while producing the same signal from small sample features. Annular optics benefit significantly from the high photon fluxes of the latest x-ray sources to compensate for their overall smaller cross section. Using numerical simulations, we show that annular optics offer superior optical performance for sample features close to the resolution limit of the optic
High pressure structural and lattice dynamics study of -InSe
No full textLayered -InSe has been studied using a combined in situ synchrotron angle-dispersive powder x-ray diffraction and Raman spectroscopy study in a diamond anvil cell up to 60+ GPa, at room temperature. Helium, which remains fairly hydrostatic up to the highest pressure in this study, was used as the pressure-transmitting medium. The results from both experimental methods reveal a pressure-induced structural phase transition from -InSe to a monoclinic -InSe structure at ≈1 GPa, in agreement with previous studies. Based on our detailed measurements using both experimental techniques and the F–f formalism, the -InSe structure remains stable up to 45 GPa, without a clear indication of a phase transition toward the previously reported -InSe phase. Above this pressure, Se adopts a disordered solid-solution-like orthorhombic structure, phase IV. The results are discussed in comparison with the relevant previous studies of -InSe under pressure
Timing Performance of the DESY Chip V2 in a 65 nm CIS Technology
No full textMonolithic Active Pixel Sensors (MAPS) produced in CMOS image sensor (CIS) technology are a promising candidate for meeting the stringent requirements for vertex detectors at future lepton colliders. Recently, a 65 nm CIS process has become available to the high-energy physics community, offering enhanced integration density and lowered power consumption. In this context, the DESY Chip V2 was developed as a test chip, studying the performance and intricacies of this technology. The chip features a 2 × 2 pixel test structure with a pixel pitch of 35 × 25 μm2. In contrast to complementary prototypes that rely on reading out digitised data only, the frontend voltage output can be measured, providing deeper insight into the charge collection and frontend response.The work presented in this thesis covers the commissioning and integration of the DESY Chip V2 into existing frameworks, a charge calibration and a test beam campaign with the analysis of the recorded data. Special focus is placed on the time resolution and the interaction of the placement of n-wells with the charge collection
Azimuthal anisotropies of charged particles with high transverse momentum in Pb+Pb collisions at TeV with the ATLAS detector
No full textA measurement is presented of elliptic () and triangular () azimuthal anisotropy coefficients for charged particles produced in Pb+Pb collisions at TeV using a dataset corresponding to an integrated luminosity of nb collected with the ATLAS detector at the LHC in 2018. The values of and are measured for charged particles over a wide range of transverse momentum (), 1-400 GeV, and Pb+Pb collision centrality, 0-60%, using the scalar product and multi-particle cumulant methods. These methods are sensitive to event-by-event fluctuations and non-flow effects in the measurements of azimuthal anisotropies. Positive values of are observed up to a of approximately 100 GeV from both methods across all centrality intervals. Positive values of are observed up to approximately 25 GeV using both methods, though the application of the three-subevent technique to the multi-particle cumulant method leads to significant changes at the highest . At high ( GeV), charged particles are dominantly from jet fragmentation. These jets, and hence the measurements presented here, are sensitive to the path-length dependence of parton energy loss in the quark-gluon plasma produced in Pb+Pb collisions
The kinetics of nsp7-11 polyprotein processing and impact on complexation with nsp16 among human coronaviruses
No full textIn severe-acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, polyproteins (pp1a/pp1ab) are processed into non-structural proteins (nsps), which largely form the replication/transcription complex (RTC). The polyprotein processing and complex formation is critical and offers potential therapeutic targets. However, the interplay of polyprotein processing and RTC-assembly are poorly understood. Here, we studied two key aspects: The influence of the pp1a terminal nsp11 on the order of polyprotein processing by viral main protease Mpro and the influence of polyprotein processing on core enzyme complex formation. We established a method based on native MS to determine rate constants k considering the structural environment. This enabled us to quantify the multi-reaction kinetics of coronavirus polyprotein processing for the first time. Our results serve as a blueprint for other multi-cleavage reactions. Further, it offers a detailed and quantifiable perspective to the dynamic reactions of SARS-CoV-2 polyprotein processing, which is required for development of novel antivirals
Observation of a cross-section enhancement near the production threshold in =13 TeV pp collisions with the ATLAS detector
No full textA measurement is presented of production in the invariant-mass region near the pair production threshold,∼345GeV, in final states with two charged leptons and multiple jets. The measurement is based on 140fb of proton–proton collision data collected at =13TeV with the ATLAS detector. The data are compared to two models of production: a baseline model including only perturbative QCD (pQCD) predictions for the hard process, and an extended model that, in addition to the pQCD predictions, incorporates state-of-the-art Monte Carlo simulations of colour-singlet quasi-bound-state formation near the threshold. The agreement between the data and the models is quantified via a profile-likelihood fit to the reconstructed distributions, in bins of two angular observables sensitive to spin-correlations in the system. An excess of events is observed over the baseline pQCD prediction, with an observed significance of 7.7 standard deviations. This excess is consistent with the formation of colour-singlet, S-wave, quasi-bound states as predicted by non-relativistic QCD, and corresponds to an observed cross-section of 9.01.3pb
Radio emission from airplanes as observed with RNO-G
No full textThis paper describes how intentional and unintentional radioemission from airplanes is recorded with the Radio NeutrinoObservatory Greenland (RNO-G). We characterize the receivedsignals and define a procedure to extract a clean set of impulsivesignals. These signals are highly suitable for instrumentcalibration, also for future experiments. A set of signals is usedto probe the timing precision of RNO-G in-situ, which is found tomatch expectations. We also discuss the impact of these signals onthe ability to detect neutrinos with RNO-G