Search for monotop signatures in proton-proton collisions at root s=8 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for resonances and quantum black holes using dijet mass spectra in proton-proton collisions at root s=8 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Measurement of the cross section ratio σttbb/σttjj in pp collisions at √s = 8 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Accidental symmetries and massless quarks in the economical 3-3-1 model

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Colorless top partners, a 125 GeV Higgs boson, and the limits on naturalness

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Flavor physics in warped space

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Search for physics beyond the standard model in dilepton mass spectra in proton-proton collisions at root s=8 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Searches for supersymmetry using the M-T2 variable in hadronic events produced in pp collisions at 8 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for vector-like T quarks decaying to top quarks and Higgs bosons in the all-hadronic channel using jet substructure

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Searches for heavy Higgs bosons in two-Higgs-doublet models and for t→ch decay using multilepton and diphoton final states in pp collisions at 8 TeV

Searches are presented for heavy scalar (H) and pseudoscalar (A) Higgs bosons posited in the two doublet model (2HDM) extensions of the standard model (SM). These searches are based on a data sample of pp collisions collected with the CMS experiment at the LHC at a center-of-mass energy of root s = 8 TeV and corresponding to an integrated luminosity of 19.5 fb(-1). The decays H -> hh and A -> Zh, where h denotes an SM-like Higgs boson, lead to events with three or more isolated charged leptons or with a photon pair accompanied by one or more isolated leptons. The search results are presented in terms of the H and A production cross sections times branching fractions and are further interpreted in terms of 2HDM parameters. We place 95% C.L. cross section upper limits of approximately 7 pb on sigma B for H -> hh and 2 pb for A -> Zh. Also presented are the results of a search for the rare decay of the top quark that results in a charm quark and an SM Higgs boson, t -> ch, the existence of which would indicate a nonzero flavor-changing Yukawa coupling of the top quark to the Higgs boson. We place a 95% C.L. upper limit of 0.56% on B(t -> ch).

Search for anomalous production of events with three or more leptons in pp collisions at root s=8 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

QCD sum rules calculation of heavy Λ semileptonic decay

We set up sum rules for heavy lambda decays in a full QCD calculation which in the heavy quark mass limit incorporates the symmetries of heavy quark effective theory. For the semileptonic Λc decay we obtain a reasonable agreement with experiment. For the Λb semileptonic decay we find at the zero recoil point a violation of the heavy quark symmetry of about 20%. © 1998 Published by Elsevier Science B.V. All rights reserved.

Problem of the statistical model in deep inelastic scattering phenomenology

Recent deep inelastic data leads to an up-down quark asymmetry of the nucleon sea. Explanations of the flavour asymmetry and the di-lepton production in proton-nucleus collisions call for a temperature T ≈ 100 MeV in a statistical model. This T may be conjectured as being due to the Fulling-Davies-Unruh effect. But it is not possible to fit the structure function itself.

Epsilon(b) constrainsts on self-couplings of vector bosons

We analyze the constraints on possible anomalous contributions to the W+W-Z vertex coming from non-universal radiative corrections to the Z → bb̄ width. We parametrize these corrections in terms of ∈b and use the LEP data to establish the allowed values for the anomalous triple couplings. We examine all CP conserving effective operators that exhibit SU(2)L × U(1)Y gauge invariance and do not give any tree level contribution to the present experimental observables. For some of these operators our constraints are comparable with the bounds coming from a global fit of the oblique parameters, which evidences the increasing relevance of the precise measurement of the b-quark parameters at LEP for the search of new physics.

Probing minimal supergravity at the CERN LHC for large tan beta

For large values of the minimal supergravity model parameter tan beta, the tau lepton and the bottom quark Yukawa couplings become large, leading to reduced masses of tau sleptons and b squarks relative to their first and second generation counterparts, and to enhanced decays of charginos and neutralinos to tau leptons and b quarks. We evaluate the reach of the CERN Large Hadron Collider (LHC) pp collider for supersymmetry in the MSUGRA model parameter space. We find that values of m((g) over tilde) similar to 1500-2000 GeV can be probed with just 10 fb(-1) of integrated luminosity for tan beta values as high as 45, so that MSUGRA cannot escape the scrutiny of LHC experiments by virtue of having a large value of tan beta. We also perform a case study of an MSUGRA model at tan beta = 45 where (Z) over tilde(2)-->tau<(tau)over tilde>(1) and (W) over tilde(1)-->tau(1)nu(tau) with similar to 100% branching fraction. In this case, at least within our simplistic study, we show that a di-tau mass edge, which determines the value of m((Z) over tilde 2) - m((Z) over tilde 1), can still be reconstructed. This information can be used as a starting point for reconstructing SUSY cascade decays on an event-by-event basis, and can provide a strong constraint in determining the underlying model parameters. Finally, we show that for large tan beta, there can be an observable excess of tau leptons, and argue that tau signals might serve to provide new information about the underlying model framework. [S0556-2821(99)04205-8].