La prise de données réalisée en 2015 par la collaboration COMPASS au CERN a permis de collecter un nombre significatif de paires de muons de grande masse. Ces dernières proviennent de l’interaction d’un faisceau de pions négatifs d’impulsion 190 GeV/c sur des cibles d’ammoniac (NH₃), d’aluminium (Al) ou de tungstène (W). Ce travail de thèse décrit les différentes étapes d’analyse des données de Drell-Yan dans la région de masse entre 4.3 et 8.5 GeV/c², depuis la reconstruction des traces du pion incident et des muons diffusés, jusqu’à l'extraction des sections efficaces finales. Ces étapes comprennent la détermination du flux incident et des densités des trois cibles, l’évaluation des différentes efficacités expérimentales, le calcul de l’acceptance de l’appareillage par simulation Monte-Carlo et la réduction des données à des paires de muons. Présentées en fonction de la variable de Feynman xF et de l’impulsion transverse pT, les sections efficaces Drell-Yan sont comparées aux calculs théoriques aux ordres NLO et NNLO, ainsi qu’aux résultats des expériences antérieures. Une interprétation plus poussée des résultats donnera accès aux distributions des partons dans le pion et à l’étude des effets de la matière froide dans les noyaux. / The COMPASS collaboration at CERN collected a significant amount of Drell-Yan data in 2015. The measured lepton pairs originate from the interaction of a negatively charged pion beam at 190 GeV/c with ammonia targets (NH₃), aluminum (Al) or tungsten (W). The analysis step using the Drell-Yan data are discussed in the mass range between 4.3 and 8.5 GeV/c², starting from the reconstruction of the incoming pion beam and the scattered muons, until the extraction of the Drell-Yan cross-sections. These steps include the determination of the incoming beam flux and the three target densities, the overall efficiency of the experimental apparatus, the acceptance of this spectrometer using Monte-Carlo simulations, and the reduction of the initial data to muon pairs. The Drell-Yan cross-sections, expressed in terms of the scaling variable xF and the transverse momentum pT, are compared with theoretical predictions at NLO and NNLO, as well as some previously published results. An advanced interpretation of these results would give access to the partonic distribution of the pion and lead to the study of cold nuclear matter effects.

Two precision measurements have been performed using the large number of dileptonand diphoton events produced in pp¯ and pp collisions. A measurement of thedistribution of the kinematic variable φ∗ηin the Drell-Yan process is performed inbins of boson rapidity and invariant mass using 10.4 fb−1 data collected by the D0experiment with a centre-of-mass energy of 1.96 TeV in pp¯ collisions. φ∗η, definedin terms of lepton track directions, is well-measured and is sensitive to higher ordereffects in Quantum chromodynamics (QCD). Data are compared to predictions fromstate-of-the-art QCD Monte Carlo programs and are in good agreement. Measurementsof the production of prompt photon pairs are performed using 20.24 fb−1 datacollected by the ATLAS experiment at 8 TeV in pp collisions. QCD Monte Carloprograms including higher order effects are found to describe the data. In addition,a luminosity algorithm that renders its susceptibility to noise and inefficiency of certainmodules in the diamond beam monitor has been proposed and validated usingATLAS simulations.

Title: Study of azimuthal asymmetries in COMPASS Drell-Yan data Author: Bc. Markéta Pešková Department / Institute: Department of Low Temperature Physics Supervisor of the master thesis: M.Sc. Michael Finger, CSc. Abstract: Drell-Yan (DY) process, i.e. a lepton pair production in hadron-hadron interaction, is one of the unique tools to study structure of hadrons. In this thesis we present its theoretical background and its link to description of the nucleon spin structure. The corresponding formalism of the Parton Distribution Functions (PDF) and the Transverse Momentum Dependent Parton Distribution Functions (TMD PDF) is explained in some detail. The fundamental theoretical prediction of a sign change of the T-odd TMDs in the DY and Semi- inclusive DIS (SIDIS) is described. In the following a concise description of the COMPASS apparatus is given with the emphasis on the setup modification needed and implemented for the Drell-Yan measurement performed in 2014 and 2015 with 190 GeV/c2 beam of negative pions and the proton target (polarised in 2015). In the final chapter we present our independent analysis of the DY data taken in 2015. Three azimuthal asymmetries giving access to the different TMD PDF were extracted using the dimuon events from a mass region of 4.3 to 8.5 GeV/c2 . Our results are in agreement...

A measurement of the Drell-Yan differential cross section at low invariant mass is presented in the di-muon channel. A 1.64 pb−1 dataset of √s = 7 TeV proton-proton collision data collected by the ATLAS experiment at the LHC is used. The measurement is made in an invariant mass range of 26 < M < 66 GeV where M is the invariant mass of the muon pair. A review of the relevant theoretical physics and the ATLAS detector is made. The analysis is described with particular attention paid to the determination of the isolation efficiency corrections for the Monte Carlo and the estimate of the multijet background. The fiducial differential cross section is calculated with a statistical uncertainty that varies between 0.8% and 1.2%. The systematic uncertainty is seen to vary between 2.4% and 4.1%. A cross section extrapolated to the full phase space is also presented. This is dominated by theoretical uncertainties from the variation of the factorisation and renormalisation scales. The obtained fiducial differential mass cross section is compared to theoretical predictions at NLO and NNLO in perturbative QCD. It is shown that a move beyond NLO is needed to describe the distribution well due to the restrictions of using a fixed order theoretical prediction. A combination with the electron channel measurement is also briefly discussed as well as comparisons to a di-muon measurement in an extended invariant mass range. This allows similar, but stronger conclusions to be drawn. A discussion is made of a PDF fit that uses the measurement presented here. The fit demonstrates the impact of the measurement on the PDFs and further supports the conclusion that a move to NNLO in pQCD is needed to describe the data.

LHC proton-proton collisions at a centre of mass energy of $\sqrt{s} = 7 TeV were observed in 2011. From a 1.68 fb$^{-1}$ sample of the data collected using the ATLAS detector, electron-positron pairs originating from the Drell-Yan process were selected using a cut based analysis. After the selection process, an estimate of the background was determined followed by the selection efficiency, detector resolution, reconstruction efficiency, and kinematic acceptance. Using these, the Drell-Yan differential cross section was calculated as a function of invariant mass between 26 and 66 GeV/c$^2$. This measurement has a precision between 12.4\% and 8.01\% from the lower invariant mass bins to the higher ones. The Drell-Yan cross section in proton-proton collisions depends on empirical quantities known as parton distribution functions which parametrize the structure of the proton. The measurement outlined in this thesis observes a region in parton distribution function phase space previously untouched by experiments. / Graduate

Heidelberg, Univ., Diss., 2007.

The measurement of the shape of the Z boson rapidity distribution for drell-yan events at a center-of-mass energy of 1.96 TeV is presented in this thesis. Data collected with the D0 detector during the whole RunII period of the Fermilab Tevatron proton-antiproton collider are used. By using these data with an integrated luminosity of up to L = 9.86~$fb^{-1}$, the uncertainties on the rapidity distribution in the forward region are significantly reduced compared with previous measurements. The measurement is made for events with electron-positron mass 66 < M(ee) < 111 GeV. Predictions of Next-to-Leading-Order(NLO) QCD theory with CTEQ and MSTW parton distribution functions (PDFs) are found to agree well with the data over the full rapidity range.

E1039/SpinQuest, a transversely-polarized Drell-Yan experiment at Fermilab, plans to use the 120 GeV proton beam and polarized NH3 and ND3 cryogenic targets to study azimuthal asymmetries in dimuon production to extract the magnitude as well as sign of the sea quarks Sivers functions. The SpinQuest spectrometer is optimized to detect oppositely-charged muons with a series of tracking chambers and hodoscope stations. The scope of this manuscript is to highlight the physics goals and the experimental setup with a focus on the ongoing debugging and training of one of the tracking systems, mainly drift chambers, as preparation for the upcoming commissioning and production run-periods. This work is supported in part by the US DOE contract number DE-FG02-07ER41528. Key words: Drell-Yan, Fermilab, SpinQuest, Polarization, Tracking, Drift Chambers

Cette these a pour sujet la recherche de nouvelle physique et l'etude de la production Drell-Yan dans le canal di-electron a l'aide du detecteur CMS au LHC. Certaines theories au dela du Modele Standard (extra dimensions, theories de grande unification) predisent l'existence de particules massives pouvant se desintegrer en une paire d'electrons. La selection des evenements recherches est presentee et etudiee. La strategie d'analyse est introduite et testee. Enfin, l'analyse des premieres donnees a 7 TeV est decrite et les resultats sont commentes.

University, Diss., 2001--Heidelberg. / Parallelt.: Das Auslesesystem des inneren Spurkammersystems des HERA-B-Detektors und Drell-Yan-Physik mit dem HERA-B-Detektor.