This thesis discusses recent advances in precision calculations of quantum chromodynamics and their application to the Large Hadron Collider (LHC) physics program and beyond. The first half of the thesis is dedicated to the study of vector boson fusion Higgs (VBF) production; fully differential at the next-to-next-to-leading order level (NNLO), and inclusively at next-to-next-to-next-to-leading order (N³LO). Both calculations are performed in the structure function approximation, where the VBF process is treated as a double deep inelastic scattering. For the differential calculation a new subtraction method, "projection-to-Born", is introduced and applied. We study VBF production in a number of scenarios relevant for the LHC and for Future Circular Colliders (FCC). We find NNLO corrections after typical cuts of 5-6% while differential distributions show corrections of up to 10-12% for some standard observables. For the inclusive calculation we find N³LO corrections at the order of 1-2‰. The second half of the thesis presents recent results on the matching of fixed order calculations with parton showers. We first present the POsitive Weight Hardest Emission Generator (POWHEG) method for matching next-to-leading order (NLO) calculations with parton showers. We then proceed to apply it to the case of vector boson fusion ZZjj production and discuss the results for scenarios relevant for the LHC and a possible FCC. In order to present the matching of a NNLO calculation with a parton shower, we next discuss the Multi-Scale Improved NLO (MiNLO) procedure. By applying a reweighting procedure to MiNLO improved Drell-Yan production, we obtain a generator which is NNLO accurate when integrated over all radiation while providing a fully exclusive description of the final state phase space. We compare the calculation to dedicated next-to-next-to-leading logarithm resummations and find very good agreement. The generator is also found to be in good agreement with 7 and 8 TeV LHC data.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-08T13:15:08Z No. of bitstreams: 1 dantedonizetipereira.pdf: 460175 bytes, checksum: 092f58c5d71aa77ff03d0ae0604294a1 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-06-26T18:10:56Z (GMT) No. of bitstreams: 1 dantedonizetipereira.pdf: 460175 bytes, checksum: 092f58c5d71aa77ff03d0ae0604294a1 (MD5) / Made available in DSpace on 2017-06-26T18:10:56Z (GMT). No. of bitstreams: 1 dantedonizetipereira.pdf: 460175 bytes, checksum: 092f58c5d71aa77ff03d0ae0604294a1 (MD5) Previous issue date: 2013-07-18 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta tese exploramos diferentes aspectos de teorias clássicas e quânticas de campos. Na parte clássica, examinamos o fenômeno da birrefringência eletro-magneto-óptica em ele-trodinâmica não-linear no contexto de meios materiais dielétricos não-lineares como uma correção efetiva à teoria linear maxwelliana do eletromagnetismo. Na parte quântica, seguindo o método do heat kernel em teoria quântica de campos sobre espaços curvos, derivamos e estudamos a estrutura das divergências a 1-loop para a ação efetiva de diferentes modelos. Em particular, no ramo do modelo de Yukawa, exibimos duas novas formas de ambiguidades as quais tomam lugar na ação efetiva de campos fermiônicos através do fenômeno da anomalia multiplicativa não-local. Além disso, analisamos a estrutura das divergências ultravioletas a 1-loop para um modelo recentemente proposto de gravitação massiva livre de fantasmas, e mostramos que esse modelo encontra sérias dificuldades no nível quântico. / In this thesis we explore different aspects in classical and quantum field theories. In the classical part, we examine the phenomenon of electro-magneto-optical birefringence in nonlinear electrodynamics in the context of nonlinear dielectric media as an effective correction to the linear Maxwellian theory of electromagnetism. In the quantum part, following the heat kernel method in quantum field theory on curved spaces, we derive and study the structure of the 1-loop divergences for the effective action of different models. In particular, through the Yukawa model, we show two new forms of ambiguities which take place in the effective action of fermionic fields through the phenomenon of nonlocal multiplicative anomaly. Moreover, we analyzed the structure of ultraviolet divergences at 1-loop for a recently proposed ghost-free massive gravity model, and we show that this model meets serious difficulties at the quantum level.