713 research outputs found
Full one-loop electroweak corrections to e+e- to 3 jets at linear colliders
We describe the impact of the full one-loop electroweak terms of O(alpha_s
alpha_EM^3) entering the electron-positron into three-jet cross-section from
sqrt(s)=M_Z to TeV scale energies. We include both factorisable and
non-factorisable virtual corrections and photon bremsstrahlung. Their
importance for the measurement of alpha_S from jet rates and shape variables is
explained qualitatively and illustrated quantitatively, also in presence of
b-tagging.Comment: 6 pages, to appear in the proceedings of the workshop "LC09 -- e+e-
Physics at the TeV scale and the Dark Matter Connection", 21-24 September
2009, Perugia (Italy). Minor corrections, references added
Precision electroweak calculation of the production of a high transverse-momentum lepton pair at hadron colliders
We present a detailed study of the production of a high transverse-momentum
lepton pair at hadron colliders, which includes the exact O(alpha) electroweak
corrections properly matched with leading logarithmic effects due to multiple
photon emission, as required by the experiments at the Fermilab Tevatron and
the CERN LHC. Numerical results for the relevant observables of single Z-boson
production at hadron colliders are presented. The impact of the radiative
corrections is discussed in detail. The presence in the proton of a photon
density is considered and the effects of the photon-induced partonic
subprocesses are analyzed. The calculation has been implemented in the new
version of the event generator HORACE, which is available for precision
simulations of the neutral and charged current Drell-Yan processes.Comment: October 2007, 22p
Inverse bremsstrahlung contributions to Drell-Yan like processes
The contribution of the sub-process 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
Higgs decay into four charged leptons in the presence of dimension-six operators
We study the indirect effects of New Physics in the Higgs decay into four
charged leptons, using an Effective Field Theory (EFT) approach to Higgs
interactions. We evaluate the deviations induced by the EFT dimension-six
operators in observables like partial decay width and various kinematic
distributions, including angular observables, and compare them with the
contribution of the full SM electroweak corrections. The calculation is
implemented in an improved version of the event generator Hto4l, which can
provide predictions in terms of different EFT-bases and is available for data
analysis at the LHC. We also perform a phenomenological study in order to
assess the benefits coming from the inclusion of differential information in
the future analyses of very precise data which will be collected during the
high luminosity phase of the LHC.Comment: 31 pages, 8 figures, 1 table. Version to appear on JHEP, expanded
phenomenological section including an analysis for HL-LH
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
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 < 0.001), showing a treatment effect on the reduction of infections (p < 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 < 0.001), again showing a treatment effect (p < 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/
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 < 0.001), showing a treatment effect on the reduction of infections (p < 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 < 0.001), again showing a treatment effect (p < 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/
Multiple photon corrections to the neutral-current Drell-Yan process
Precision studies of single W and Z production processes at hadron colliders
require progress in the calculation of electroweak radiative corrections. To
this end, higher-order QED corrections to the neutral-current Drell-Yan
process, due to multiple photon radiation in Z leptonic decays, are calculated.
Particular attention is paid to the effects induced by such corrections on the
experimental observables which are relevant for high-precision measurements of
the W-boson mass at the Tevatron Run II and the LHC. The calculation is
implemented in the Monte Carlo event generator HORACE, which is available for
data analysis.Comment: 16 pages, 4 figures, 3 tables, JHEP3 styl
Evaluation of the Theoretical Uncertainties in the Z to ll Cross Sections at the LHC
We study the sources of systematic errors in the measurement of the Z to ll
cross-sections at the LHC. We consider the systematic errors in both the total
cross-section and acceptance for anticipated experimental cuts. We include the
best available analysis of QCD effects at NNLO in assessing the effect of
higher order corrections and PDF and scale uncertainties on the theoretical
acceptance. In addition, we evaluate the error due to missing NLO electroweak
corrections and propose which MC generators and computational schemes should be
implemented to best simulate the events.Comment: 23 pages, 52 eps figures, LaTeX with JHEP3.cls, epsfig. Added a
reference, acknowledgment, and a few clarifying comments. 4/29: Changes in
references, minor rewordings and misprint corrections, and one new table
(Table 4) comparing CTEQ and MRST PDFs in the NNLO calculation. Version 6
adds email addresses and corrects one referenc
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