Hadronic Production of a Higgs Boson in Association with a Jet at Next-to-Next-to-Leading Order

In this thesis the production of a Higgs boson in association with a hadronic jet at the Large Hadron Collider is studied using the effective interaction between the Higgs boson to gluons induced by a heavy quark. The Leading Order (LO), Next- to-Leading Order (NLO) and Next-to-Next-to-Leading Order (NNLO) perturbative QCD corrections are studied for all of the parton channels. The infrared (IR) diver- gent behaviour of the various contributions to the partonic cross section is regulated using the antenna subtraction formalism. This method has previously been used at NNLO in the calculation of three jets production in the e+e− annihilation and for the gluonic dijet production via proton collision. The research presented in this thesis extends the antenna formalism to include scattering processes in which the initial state parton changes its identity. All contributions to the pp → H+jet pro- cesses are calculated at LO, NLO and NNLO and numerically tested to demonstrate the convergence between the matrix elements and the antenna subtraction terms in the various unresolved limits. As an example of the phenomenological impact of this work, numerical results for the total and differential Higgs plus one jet cross sections are presented for the purely gluonic subprocesses

Recent progress in QCD at the LHC

Perturbative Quantum Chromodynamics has experienced an impressive progress in the last few years, boosted by the requirements of the LHC experimental program. In this contribution, I briefly review a selection of recent results in QCD and LHC phenomenology, covering progress in parton distribution functions, automation of NLO calculations, merging and matching at NLO, new calculations at NNLO accuracy and their matching to parton showers, and new developments and techniques in jet physics and jet substructure tools.Comment: 10 pages, 3 figures, to appear in the proceedings of the "Rencontres de physique de la Vallee d'Aoste 2014" Conference, La Thuile, Italy, February 201

Standard Model physics at the LHC

In this contribution to the volume "From My Vast Repertoire -- The Legacy of Guido Altarelli" I discuss selected topics of Standard Model (SM) physics at the LHC and their connection to the work of Guido Altarelli. An overarching connection is given by Guido's fundamental contributions to our understanding of the strong force, parton distribution functions and their evolution, and techniques to calculate theoretical predictions through perturbative Quantum Chromodynamics. The increasingly precise LHC measurements of diverse processes can be confronted with SM predictions relying on these foundations to test the SM and contribute to the knowledge of the proton structure. The LHC experiments have also started to perform precise measurements of SM parameters, such as the mass of the W boson, and have measured a variety of processes sensitive to interactions of multiple electroweak bosons. The discovery of the Higgs boson in 2012 and the measurements of its properties are crucial to establish the nature of the mechanism of electroweak symmetry breaking and the status of these studies is summarised.Comment: Contribution to the volume "From my Vast Repertoire - the Legacy of Guido Altarelli" : 24 pages, 13 figure

Higgs-differential cross section at NNLO in dimensional regularisation

We present an analytic computation of the Higgs production cross section in the gluon fusion channel, which is differential in the components of the Higgs momentum and inclusive in the associated partonic radiation through NNLO in perturbative QCD. Our computation includes the necessary higher order terms in the dimensional regulator beyond the finite part that are required for renormalisation and collinear factorisation at N$^3$LO. We outline in detail the computational methods which we employ. We present numerical predictions for realistic final state observables, specifically distributions for the decay products of the Higgs boson in the $\gamma\gamma$ decay channel.Comment: 27 pages, 6 awesome figure

NLO QCD corrections for W^+W^- pair production in association with two jets at hadron colliders

We compute the NLO QCD corrections to the pair production of W-bosons in association with two jets at the Tevatron and the LHC. This process is an important background to heavy Higgs-boson production in association with two jets, either in gluon or weak boson fusion. We consider leptonic decays of W-bosons and include all the spin correlations exactly. For natural choices of the renormalization scale, the NLO QCD corrections to pp(ppbar) -> W^+W^-jj are moderate but different for various values of the center-of-mass collision energy at the LHC and the Tevatron, emphasizing the need to compute them explicitly.Comment: 28 pages, 12 figure