Towards causal modeling of nutritional outcomes

International audienceThis paper aims at observational causal modelling, investigating the causal relationships between food consumption and health status, exploiting the proprietary Kantar database. This database describes the socioeconomic characteristics and consumption habits of a few dozen thousands households; in particular, the consumed food items are documented almost at the level of precision of barcodes. A first challenge for this observational causal study lies in the number of hidden confounders, ranging from genetic factors to life styles (i.e. smoking and sport habits), not documented in the data. Taking inspiration from the Deconfounder approach (Wang and Blei, 2019b), substitute hidden confounders based on dietary patterns − viewed as characteristics of the alimentary lifestyle − are extracted from the database and exploited to block the biases due to hidden confounders. A second challenge lies in the fact that the data size hardly allows for investigating a number of fine-grained interventions. We thus define a new type of intervention, enabled by the data structure and referred to as macro-intervention, acting on the full basket of food items; an example of such macro-intervention is to replace every non-organic product in a household basket with its organic counterpart. The average treatment effect of this macro-intervention is assessed in the context of the substitute hidden confounders, using inverse propensity weighted estimates to control for covariates such as wealth or education

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Measurement of the total W- and Z-boson production cross sections in pp collisions at 2.76 TeV with the ATLAS detector

Es werden Messungen der totalen Wirkungsquerschnitte der Prozesse pp → W/Z → ll′ in Endzuständen mit Elektronen und Myonen präsentiert. Für diese Analyse werden Daten, die im Jahr 2013 mit dem ATLAS-Detekor am LHC bei einer Schwerpunktsenergie von √s= 2.76 TeV aufgezeichnet wurden und einer integrierten Luminosität von pb−1 entsprechen, verwendet. In dieser Analyse werden mehrere Quellen systematischer Unsicherheiten berücksichtigt. Die Untergründe werden sowohl mittels Simulationen (für elektroschwache und tt ̄ Un- tergründe) als auch mithilfe datengetriebener Methoden (für den Multi-Jet Untergrund) abgeschätzt. Die Resultate der Elektron- und Myon-Kanäle werden kombiniert und ergeben die folgenden Wirkungsquerschnitte: sigma_fid(W → lν) = 2206.3±20.2(stat.)±10.6(sys.)±68.4(lumi.)[pb], sigma_fid(Z → ll) = 200.4±6.1(stat.)±0.3(sys.)±6.2(lumi.)[pb]. Die kombinierten Wirkungsquerschnitte werden zur Berechnung der Wirkungsquerschnitts- Verhältnisse W/Z und W+/W− benutzt. Die Ergebnisse werden mit QCD-Berechnungen unterschiedlicher Ordnungen verglichen. Der Einfluss dieser Messung auf Partonverteilungsfunktionen (parton distribution func- tions, PDFs) wird abgeschätzt. Die gesamte Unsicherheit dieser Messungen ist vergleich- bar mit den Unsicherheiten aktueller PDFs, weshalb diese Analyse zur Einbeziehung in zukünftige PDF-Bestimmungen geeignet ist. Außerdem wurden Studien zur Frozen Showers Methode zur schnelleren Simulation von Ereignissen im ATLAS-Detektor durchgeführt. Es wurde eine neue Methode zur Gener- ierung einer Frozen Showers Bibliothek entwickelt, die eine Reduzierung der für diesen Abschnitt benötigten Zeit erlaubt.Measurements of the total pp → W/Z → ll′ cross sections in the electron and muon s = 2.76 TeV with the ATLAS detector at the LHC (in 2013), corresponding to a total integrated luminosity of 4 channels are presented. Data collected at a center-of-mass energy pb−1, are used for this analysis. In this measurement, several sources of systematic uncertainties are estimated. The back- ground contribution is estimated using simulation (for electroweak and tt ̄ backgrounds) as well as data-driven methods (for the multijet background). The combined results for electron and muon channels provide the following cross sections: sigma_fid(W → lν) = 2206.3±20.2(stat.)±10.6(sys.)±68.4(lumi.)[pb], sigma_fid(Z → ll) = 200.4±6.1(stat.)±0.3(sys.)±6.2(lumi.)[pb]. The combined cross sections are used for the calculation of the W/Z and W+/W− cross section ratios. These results are compared with different orders of QCD calculations. The effect of the addition of the measured cross sections to the parton density functions (PDF) is estimated. The total uncertainty of the measurements is comparable to the current global PDF uncer- tainties, which makes them applicable for future PDF determination. Additionally, studies of the Frozen Showers method for fast simulation have been per- formed. A new method of Frozen Showers library generation, allowing to reduce time spend on this stage, is developed

Measurement of W production in pp collisions at =2.76\sqrt =2.76 TeV with the ATLAS detector

Probing W production cross-section in pp collisions for a range of center of mass energies from 2.76 to 13 TeV provides additional constraints for the parton densities functions. This talk presents the measurement of W cross-section at √s = 2.76 TeV in 2013 data in electron and muon decay channels. Based on integrated luminosity 4 pb−1 collected in 2013 there are around 13k selected events and this leads to precision of the cross-section measurement at a few percent level

High Precision Measurement of the differential W and Z boson cross-sections

Measurements of the Drell-Yan production of W and Z/gamma bosons at the LHC provide a benchmark of our understanding of perturbative QCD and probe the proton structure in a unique way. The ATLAS collaboration has performed new high precision measurements at center-of-mass energies of 7. The measurements are performed for W+, W- and Z/gamma bosons integrated and as a function of the boson or lepton rapidity and the Z/gamma* mass. Unprecedented precision is reached and strong constraints on Parton Distribution functions, in particular the strange density are found. Z cross sections are also measured at a center-of-mass energies of 8TeV and 13TeV, and cross-section ratios to the top-quark pair production have been derived. This ratio measurement leads to a cancellation of several systematic effects and allows therefore for a high precision comparison to the theory predictions