Comparisons of the Monte Carlo programs HORACE and WINHAC for single-W-boson production at hadron colliders

We present the comparisons of two independent Monte Carlo event generators, HORACE and WINHAC, for single-W-boson production in hadronic collisions with multiphoton effects in leptonic W decays. These comparisons were performed first at the parton level with fixed quark-beams energy, and then at the hadron level for proton-proton collisions at the LHC. In general, a good agreement between the two programs has been found. Possible sources of differences in some of the presented results are discussed. We also present and discuss the effects of including non-zero quark masses for the main single-W-boson observables at the LHC.Comment: 32 pages, 40 PostScript figure

New standards for nutrition science, concepts and methods—novel approach to substantiate cause- and -effect relationships in nutritional science by ranking studies and subsequent statistical modelling

In any scientific field, demonstrating cause-and-effect relationships is of the utmost importance, however difficult to achieve. The present study aims to establish an objective approach to substantiate cause-and-effect relationships. Our approach consisted of ranking published studies and subsequently using the best performing studies to construct and validate a statistical model. For the first part, studies on the association between vitamin D status and COVID-19 severity (morbidity/mortality) in hospitalized patients were identified and ranked using a combination of physiological and statistical relevance, including dose-dependency, power evaluation, confounding, physiological mechanisms, and target population. The various ranking criteria were developed in an iterative process, taking into account the Bradford Hill criteria. For the second part, a two-step statistical modelling strategy was implemented. Firstly, a multivariate model was constructed and secondly, this model was validated using data from at least one other independent study with a similar design. The sensitivity (percentage of correctly detected cases by the model) and specificity (percentage of correctly detected non-cases by the model) was assessed in both studies, and the results of both studies (model-making and model-testing) were compared using the chi-square test with expectation. Five ranking criteria were defined with a maximum score of 67 points. Six studies were selected with scores ranging between 27 and 47 points [1–6]. The highest score was obtained by Hernandez et al., 2021 [1]. Unfortunately, it was not possible to obtain complete independent datasets of these studies. Therefore, to evaluate our approach in cause- and -effect relationships, two datasets were selected of studies on the effects of postbiotic intake on the incidence of pulmonary and gastrointestinal infections in children aged 1 to 4 years [7,8]. A logistic confounding model in combination with a discriminant analysis was applied on the first (model-making) study resulting in an internal sensitivity and specificity of 78% and 100%, respectively (p &lt; 0.001), showing a treatment effect on the reduction of infections (p &lt; 0.001). An external validation of the acquired model in a second independent (model-testing) study showed sensitivity and specificity of 76% and 80% (p &lt; 0.001), again showing a treatment effect (p &lt; 0.001). The sensitivity and specificity were not statistically different indicating similarity of the impact by the explanatory variables in both datasets. Overall, the combination of ranking studies and statistical modelling supports the validation of cause-and-effect relationships using objective criteria. Demonstrating consistency in associations by replication and robustness testing contributes to proof of concept in causative relations.<br/

Efficient operation of a high-power X-band gyroklystron

Experimental studies of amplification in a two-cavity X-band gyroklystron are reported. The system utilizes a thermionic magnetron injection gun at voltages up to 440 kV and currents up to 190 A in 1-μs pulses. Optimum performance is achieved by tapering the magnetic-field profile. Peak powers of 20 MW in the TE01 mode at 9.87 GHz are measured with calibrated crystals and with methanol calorimetry. Resultant efficiencies are in excess of 31% and large-signal gains surpass 26 dB. The experimental results are in good agreement with simulated results from a partially self-consistent, nonlinear, steady-state code

High-power operation of a K-band second harmonic gyroklystron

Amplification studies of a two-cavity second-harmonic gyroklystron are reported. A magnetron injection gun produces a 440 kV, 200–245 A, 1 μs beam with an average perpendicular-to-parallel velocity ratio slightly less than 1. The TE011 input cavity is driven near 9.88 GHz and the TE021 output cavity resonates near 19.76 GHz. Peak powers exceeding 21 MW are achieved with an efficiency near 21% and a large signal gain above 25 dB. This performance represents the current state of the art for gyroklystrons in terms of the peak power normalized to the output wavelength squared

Inverse bremsstrahlung contributions to Drell-Yan like processes

The contribution of the sub-process $\gamma q \to q' l_1\bar{l}_2$ in hadron-hadron interactions is considered. It is a part of one-loop electroweak radiative corrections for the Drell-Yan production of lepton pairs at hadron colliders. It is shown that this contribution should be taken into account aiming at the 1% accuracy of the Drell-Yan process theoretical description. Both the neutral and charged current cases are evaluated. Numerical results are presented for typical conditions of LHC experiments.Comment: 11 pages, 8 figure

Higher-order QED corrections to W-boson mass determination at hadron colliders

The impact of higher-order final-state photonic corrections on the precise determination of the W-boson mass at the Tevatron and LHC colliders is evaluated. In the presence of realistic selection criteria, the shift in the W mass from a fit to the transverse mass distribution is found to be about 10 MeV in the $W \to \mu \nu$ channel and almost negligible in the $W \to e \nu$ channel. The calculation, which is implemented in a Monte Carlo event generator for data analysis, can contribute to reduce the uncertainty associated to the W mass measurement at future hadron collider experiments.Comment: 9 pages, 2 figures, 1 table, RevTe

One-loop corrections to the Drell--Yan process in SANC (II). The neutral current case

Radiative corrections to the neutral current Drell--Yan-like processes are considered. Complete one-loop electroweak corrections are calculated within the SANC system. Theoretical uncertainties are discussed. Numerical results are presented for typical conditions of LHC experiments.Comment: 17 pages, 9 figures, 3 table

Electrolyte gate dependent high-frequency measurement of graphene field-effect transistor for sensing applications

We performed radiofrequency (RF) reflectometry measurements at 2.4 GHz on electrolyte-gated graphene field-effect transistors (GFETs) utilizing a tunable stub-matching circuit for impedance matching. We demonstrate that the gate voltage dependent RF resistivity of graphene can be deduced even in the presence of the electrolyte which is in direct contact with the graphene layer. The RF resistivity is found to be consistent with its DC counterpart in the full gate voltage range. Furthermore, in order to access the potential of high-frequency sensing for applications, we demonstrate time-dependent gating in solution with nanosecond time resolution.Comment: 14 pages, 4 figure

Protective effect of ultrathin alumina film against diffusion of iron into carbon fiber during growth of carbon nanotubes for hierarchical composites investigated by ptychographic X-ray computed tomography

Composite materials based on carbon fiber (CF) are prone to failure at the fiber-matrix interface upon compression or stress transverse to the fiber axis. The direct growth of carbon nanotubes on CF constitutes a novel approach to enhance the mechanical properties of the interface. However, the challenge is that, during the growth, tensile properties of the fiber are altered due to the diffusion effect of iron nanoparticles used in the process, leading to CF surface defect formation. In this work, we deliver and discuss an analysis methodology on ptychographic X-ray computed tomography (PXCT) images in order to assess the iron nanoparticle abundance within CFs. PXCT provides 50 nm - resolved 3D electron density maps of the CFs. We evidence the protective effect of an ultrathin alumina film against iron infiltration into CF during the CNT growth. This method potentially allows to evaluate the efficiency of other diffusion-minimizing approaches. The conclusions of the PXCT examination are validated by energy-dispersive X-ray spectroscopy and scanning transmission electron microscopy carried out on thin sample slices cut with a focused ion beam. The results provide a new insight into the mechanical performance of CFs and therefore constitute valuable knowledge for the development of hierarchical composites

Z-boson as "the standard candle" for high precision W-boson physics at LHC

In this paper we propose a strategy for measuring the inclusive W-boson production processes at LHC. This strategy exploits simultaneously the unique flexibility of the LHC collider in running variable beam particle species at variable beam energies, and the configuration flexibility of the LHC detectors. We propose their concrete settings for a precision measurement of the Standard Model parameters. These dedicated settings optimise the use of the Z boson and Drell-Yan pair production processes as ``the standard reference candles''. The presented strategy allows to factorise and to directly measure those of the QCD effects which affect differently the W and Z production processes. It reduces to a level of 10^{-4} the impact of uncertainties in the partonic distribution functions (PDFs) and in the transverse momentum of the quarks on the measurement precision. Last but not the least, it reduces by a factor of 10 an impact of systematic measurement errors, such as the energy scale and the measurement resolution, on the W-boson production observables.Comment: 20 pages, 4 figure