Combined Forward-Backward Asymmetry Measurements in Top-Antitop Quark Production at the Tevatron

The CDF and D0 experiments at the Fermilab Tevatron have measured the asymmetry between yields of forward- and backward-produced top and antitop quarks based on their rapidity difference and the asymmetry between their decay leptons. These measurements use the full data sets collected in proton-antiproton collisions at a center-of-mass energy of $\sqrt s =1.96$ TeV. We report the results of combinations of the inclusive asymmetries and their differential dependencies on relevant kinematic quantities. The combined inclusive asymmetry is $A_{\mathrm{FB}}^{t\bar{t}} = 0.128 \pm 0.025$. The combined inclusive and differential asymmetries are consistent with recent standard model predictions

Charge asymmetry in top quark pair production in the di-lepton channel at the ATLAS experiment

The charge asymmetry in top quark pair production in the di-lepton $t\bar t$ channel using the ATLAS experiment at Large Hadron Collider is presented. The asymmetry is studied in the distribution of absolute rapidity difference between top and anti-top. The reconstruction of the $t\bar t$ system is based on a leading order matrix element. The lepton charge asymmetry is also presented. All results are consistent with the Standard Model.The charge asymmetry in top quark pair production in the di-lepton $t\bar t$ channel using the ATLAS experiment at Large Hadron Collider is presented. The asymmetry is studied in the distribution of absolute rapidity difference between top and anti-top. The reconstruction of the $t\bar t$ system is based on a leading order matrix element. The lepton charge asymmetry is also presented. All results are consistent with the Standard Model

Challenges in MW measurements with ATLAS and CMS

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Measurement of the W boson mass with the DO detector and determination of the strong coupling constant with the ATLAS detector

A good theoretical description of electroweak boson production in hadronic collisions at high center of mass energies is essential for the measurement of the W boson mass. The DYRES computer program allows for the precise calculation of the relevant production cross section, however, is limited in performance. In this thesis, the DYRES program was significantly improved, leading to a new tool named DYTURBO. In order to test the performance of the DYTURBO program, the transverse momentum spectrum of Z bosons, pT(Z), produced in proton-proton collisions at a center of mass energy of 13 TeV was measured, using data collected by the ATLAS Experiment at the Large Hadron Collider. Due to the large speed improvements of DYTURBO compared to previous similar theoretical tools, it was possible for the first time to extract the strong coupling constants by fitting the measured pT(Z) distribution. This approach yields a value of αs(M²) = 0.1177 ± 0.0014 (syst+syst) ± 0.0086 (theo), in agreement with other measurements of the ATLAS collaboration. The actual measurement of the W boson mass was developed using data of proton--anti-proton collisions, recorded from 2009 to 2010 at √s = 1.96 TeV by the DØ experiment at Tevatron. The W boson mass is extracted using the transverse energy distribution of decay electrons as well as the transverse mass observable, using a novel, two-dimensional fitting technique. The work focused on the estimation of uncertainties due to the limited knowledge of parton density functions, which are the largest theoretical uncertainties of the W boson mass measurement. Since the final W boson mass analysis was not yet approved by the collaboration at the time of the thesis submission, only the expected uncertainty can be made public at this stage. The upcoming measurement of the DØ experiment is expected to have a statistical and systematic uncertainty of 14 MeV and 19 MeV, respectively.Eine gute theoretische Beschreibung der elektroschwachen Prozesse zur Bosonen Produktion in Hadronenkollisionen bei hohen Schwerpunktsenergien ist für die Messung der Masse des W Bosons essentiell. Das DYRES Computerprogramm erlaubt die präzise Berechnung der Wirkungsquerschnitte aller relevanten Prozesse, ist dabei aber nicht sehr performant. Daher wurde im Rahmen dieser Arbeit ein neues Programm, DYTURBO, entwickelt, dass die Performanz signifikant verbessert. Um die Leistungsfähigkeit dieses Programms zu Testen, wurde das Transversalimpuls-Spektrum des Z-Bosons unter Benutzung von Daten, die am ATLAS Detektor am LHC aufgenommen wurden, gemessen. Aufgrund der im Vergleich zu anderen Softwarepaketen hohen Laufzeitverbesserungen durch DYTURBO war es nun das erste Mal möglich die starke Kopplungskonstante durch Fitten des oben genannten Spektrums zu extrakhieren. Diese Methode ergab einn Wert von αs(M²) = 0.1177 ± 0.0014 (syst+syst) ± 0.0086 (theo), der mit anderen ATLAS Messungen übereinstimmt. Die eigentliche Messung der W Boson Masse wurde anhand von Tevatron Daten mit einer Schwerpunktsenergie von √s = 1.96 TeV am DØ Experiment entwickelt. Die W Boson Masse wurde unter Nutzung der Transversalenergieverteilung zerfallender Elektronen und der Transversalmassen-Observable bestimmt. Dabei wurde eine neue, zweidimensionale Fitmethode verwendet. Diese Arbeit spezialisiert sich auf die Abschätzung sysmtematischer Unsicherheiten aufgrund des begrenzten Wissens der Parton-Verteilungsfunktion, was die größte theoretische Unsicherheit bei der Messung der W Boson Masse darstellt. Da die Analyse zur Zeit des Einreichens dieser Arbeit noch nicht von der ATLAS Kollaboration angenommen wurde, können hier nur vorläufige Unsicherheiten veröffentlich werden. Die kommende Messung am DØ Experiment werden vorrausichtlich eine statistische und systematische Unsicherheit von 14 MeV beziehungsweise 19 MeV haben

Facing up to the challenges of European society A programme for 1997-2000

Summary held at OP-EC/4169Available from British Library Document Supply Centre-DSC:OP-EC/4168 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Erratum to: DYTurbo: fast predictions for Drell–Yan processes

Drell–Yan lepton pair production processes are extremely important for standard model (SM) precision tests and for beyond the SM searches at hadron colliders. Fast and accurate predictions are essential to enable the best use of the precision measurements of these processes; they are used for parton density fits, for the extraction of fundamental parameters of the SM, and for the estimation of background processes in searches. This paper describes a new numerical program, DYTurbo, for the calculation of the QCD transverse-momentum resummation of Drell–Yan cross sections up to next-to-next-to-leading logarithmic accuracy combined with the fixed-order results at next-to-next-to-leading order (O(αS2)\mathcal {O}(\alpha _{\mathrm {S}}^2)O(αS2​)), including the full kinematical dependence of the decaying lepton pair with the corresponding spin correlations and the finite-width effects. The DYTurbo program is an improved reimplementation of the DYqT, DYRes and DYNNLO programs, which provides fast and numerically precise predictions through the factorisation of the cross section into production and decay variables, and the usage of quadrature rules based on interpolating functions for the integration over kinematic variables

DYTurbo: Fast predictions for Drell–Yan processes

Drell–Yan lepton pair production processesare extremely important for Standard Model (SM) pre-cision tests and for beyond the SM searches at hadroncolliders. Fast and accurate predictions are essential toenable the best use of the precision measurements ofthese processes; they are used for parton density fits, forthe extraction of fundamental parameters of the SM, andfor the estimation of background processes in searches.This paper describes a new numerical program,DYTurbo,for the calculation of the QCD transverse-momentumresummation of Drell–Yan cross sections up to next-to-next-to-leading logarithmic accuracy combined withthe fixed-order results at next-to-next-to-leading order(O(α2S)), including the full kinematical dependence ofthe decaying lepton pair with the corresponding spincorrelations and the finite-width effects. TheDYTurboprogram is an improved reimplementation of theDYqT,DYResandDYNNLOprograms, which provides fast andnumerically precise predictions through the factorisationof the cross section into production and decay variables,and the usage of quadrature rules based on interpolatingfunctions for the integration over kinematic variables

DYTurbo: Fast predictions for Drell–Yan processes

Drell–Yan lepton pair production processesare extremely important for Standard Model (SM) pre-cision tests and for beyond the SM searches at hadroncolliders. Fast and accurate predictions are essential toenable the best use of the precision measurements ofthese processes; they are used for parton density fits, forthe extraction of fundamental parameters of the SM, andfor the estimation of background processes in searches.This paper describes a new numerical program,DYTurbo,for the calculation of the QCD transverse-momentumresummation of Drell–Yan cross sections up to next-to-next-to-leading logarithmic accuracy combined withthe fixed-order results at next-to-next-to-leading order(O(α2S)), including the full kinematical dependence ofthe decaying lepton pair with the corresponding spincorrelations and the finite-width effects. TheDYTurboprogram is an improved reimplementation of theDYqT,DYResandDYNNLOprograms, which provides fast andnumerically precise predictions through the factorisationof the cross section into production and decay variables,and the usage of quadrature rules based on interpolatingfunctions for the integration over kinematic variables