Search

Abstract: Complete electroweak two-loop corrections to the process are presented and discussed in a Standard Model with a fourth generation of heavy fermions. The latter is studied at the LHC to put exclusion limits on a fourth generation of heavy fermions. Therefore also a precise knowledge of the electroweak (EW) next-to-leading-order (NLO) corrections is important. The corrections due to the fourth generation are positive and large for a light Higgs boson, positive but relatively small around the threshold and start to become negative for a Higgs boson mass around . Increasing further the value of the Higgs boson mass, the EW NLO effects tend to become huge and negative, , around the heavy-fermion threshold, assumed at , so that gg-fusion becomes non-perturbative. Above that threshold they start to grow again and become positive around . The behavior at even larger values of shows a positive enhancement, at . [Copyright &y& Elsevier]

Abstract: The relation between physical observables measured at LHC and Tevatron and standard model Higgs pseudo-observables (production cross section and partial decay widths) is revised by extensively using the notion of the Higgs complex pole on the second Riemann sheet of the S-matrix. The extension of their definition to higher orders is considered, confronting the problems that arise when QED (QCD) corrections are included in computing realistic observables. Numerical results are presented for pseudo-observables related to the standard model Higgs boson decay and production. The relevance of the result for exclusion plots of the standard model Higgs boson for high masses (up to 600 GeV) is discussed. Furthermore, a recipe for the analytical continuation of Feynman loop integrals from real to complex internal masses and complex Mandelstam invariants is thoroughly discussed. [Copyright &y& Elsevier]