Renato Guedes

Light Charged Higgs bosons at the LHC in 2HDMs

We present a discussion of light charged Higgs boson searches at the Large Hadron Collider (LHC) in CP-conserving 2-Higgs Doublet Models (2HDMs). Taking into account all available experimental and theoretical constraints we review all possible processes that would allow for a detection of such a particle with a mass below the top quark mass. Two different types of processes are analysed: one that depends only on tan beta and on the charged Higgs boson mass because it involves only the charged Higgs boson Yukawa couplings; the other that depends on almost all model parameters, mainly due to the presence of Higgs self-couplings. We discuss the regions of parameter space of 2HDMs that can be covered be each type of process and define some guidelines for experimental searches at the LHC.

Double neutral Higgs production in the two-Higgs doublet model at the LHC

In this work we study the production and decay of two CP-even Higgs bosons in the general CP-conserving two-Higgs doublet model at the LHC. We also study the limiting case of the decoupling scenario. For each Yukawa version of the model, we look for the region of the parameter space where a signal would be seen at the LHC. Taking into account theoretical and experimental constraints on the two Higgs doublet model parameters, we show that the cross section can be two orders of magnitude above the corresponding Standard Model cross section. We have also studied in detail the decay profile of the Higgs bosons and showed that interesting signatures may emerge for some particular values of the parameters. There are scenarios where some of the triple Higgs couplings could be measured.

Wrong sign and symmetric limits and non-decoupling in 2HDMs

A bstractWe analyse the possibility that, in two Higgs doublet models, one or more of the Higgs couplings to fermions or to gauge bosons change sign, relative to the respective Higgs Standard Model couplings. Possible sign changes in the coupling of a neutral scalar to charged ones are also discussed. These wrong signs can have important physical consequences, manifesting themselves in Higgs production via gluon fusion or Higgs decay into two gluons or into two photons. We consider all possible wrong sign scenarios, and also the symmetric limit, in all possible Yukawa implementations of the two Higgs doublet model, in two different possibilities: the observed Higgs boson is the lightest CP-even scalar, or the heaviest one. We also analyse thoroughly the impact of the currently available LHC data on such scenarios. With all 8 TeV data analysed, all wrong sign scenarios are allowed in all Yukawa types, even at the 1σ level. However, we will show that B-physics constraints are crucial in excluding the possibility of wrong sign scenarios in the case where tan β is below 1. We will also discuss the future prospects for probing the wrong sign scenarios at the next LHC run. Finally we will present a scenario where the alignment limit could be excluded due to non-decoupling in the case where the heavy CP-even Higgs is the one discovered at the LHC.

Combined effects of strong and electroweak flavor changing neutral current effective operators in top quark physics at the CERN LHC

We study the combined effects of both strong and electroweak dimension six effective operators on flavor changing top quark physics at the CERN LHC. Analytic expressions for the cross sections and decay widths of several flavor changing processes will be presented, as well as an analysis of the feasibility of their observation at the LHC.

Dimension six FCNC operators and top production at the LHC

R.A. Coimbra , P.M. Ferreira , R.B. Guedes , O. Oliveira , A. Onofre , R. Santos ∗∗ and Miguel Won †† 1 LIPDepartamento de F́ısica, Universidade de Coimbra, 3004-516 Coimbra, Portugal; 2 Centro de F́ısica Computacional, Universidade de Coimbra, 3004-516 Coimbra, Portugal; 3 Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emı́dio Navarro 1, 1959-007 Lisboa, Portugal; 4 Centro de F́ısica Teórica e Computacional, Faculdade de Ciências, Universidade de Lisboa, Avenida Professor Gama Pinto, 2, 1649-003 Lisboa, Portugal; 5 NExT Institute and School of Physics and Astronomy, University of Southampton Highfield, Southampton SO17 1BJ, United Kingdom

Charged Higgs bosons in single top production at the LHC

A bstractWe show that a light charged Higgs boson signal via τ±ν decay can be established at the Large Hadron Collider (LHC) also in the case of single top production. This process complements searches for the same signal in the case of charged Higgs bosons emerging from

Limits on strong flavor changing neutral current top couplings at the LHC

t\overline{t}

Charged Higgs discovery potential in the single top mode in 2HDMs

production. The models accessible include the Minimal Supersymmetric Standard Model (MSSM) as well a variety of 2-Higgs Doublet Models (2HDMs). High energies and luminosities are however required, thereby restricting interest on this mode to the case of the LHC running at 14 TeV with design configuration.

Very light Higgs Bosons in extended models at the LHC

The best limit on the strong FCNC anomalous couplings was obtained using the direct top production process at the Large Hadron Collider by the ATLAS collaboration. We perform a similar analysis but using a next-to-leading order generator, MEtop. We then show how the limits could be improved if the FCNC single top process pp→ tj would be included as signal. Finally we discuss a slightly modified analysis with an extra hard jet in the final state.

Higgs boson phenomenology in τ+τ− final states at the LHC

We discuss the discovery potential of a charged Higgs boson in the single top mode. The models discussed include a CP-conserving and a CP-violating version of the softly broken