Search for New Heavy Charged Bosons and Measurement of High Mass Drell Yan Production in Proton—Proton Collisions Introduction Part I: Theory Theory Foundations Theoretical Predictions and Simulation Part II: The Experimental Setup The Large Hadron Collider The ATLAS Experiment Particle Reconstruction and Identiﬁcation in ATLAS Part III: Search for New Physics in Final States with One Lepton Plus Missing Transverse Momentum at √s = 13 TeV Motivation Analysis Strategy Analysis Statistical Interpretation Conclusion and Outlook Part IV: High mass Drell Yan Cross Section Measurement at √s = 8 TeV Motivation Analysis Strategy Analysis of the Electron Channel Electron Channel Cross Section Measurement Muon Channel Cross Section Results and Interpretation Conclusion and Outlook Summary This book presents two analyses the first of which involves the search for a new heavy charged gauge boson a so called W¢ boson. This new gauge boson is predicted by some theories extending the Standard Model gauge group to solve some of its conceptual problems. Decays of the W¢ boson in final states with a lepton (ℓ±= e± µ±) and the corresponding (anti )neutrino are considered. Data collected by the ATLAS experiment in 2015 at a center of mass energy of sqrt{s}=13 TeV is used for the analysis. In turn the second analysis presents a measurement of the double differential cross section of the process pp >Z gamma^* + X > l^+l^ + X including a gamma gamma induced contribution at a center of mass energy of sqrt{s} = 8 TeV. The measurement is performed in an invariant mass region of 116 GeV to 1500 GeV as a function of invariant mass and absolute rapidity of the l^+l^ pair and as a function of invariant mass and pseudorapidity separation of the l^+l^ pair. The data analyzed was recorded by the ATLAS experiment in 2012 and corresponds to an integrated luminosity of 20.3 fb. It is expected that the measured cross sections are sensitive to the PDFs at very high values of the Bjorken x scaling variable and to the photon structure of the proton