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This white paper summarizes the activities of the Brazilian community concerning dark matter physics and highlights the importance of financial support to Brazilian groups that are deeply involved in experimental endeavours. The flagships of the Brazilian dark matter program are the Cherenkov Telescope Array, DARKSIDE, SBN and LHC experiments, but we emphasize that smaller experiments such as DAMIC and CONNIE constitute important probes to dark sectors as well and should receive special attention. Small experimental projects showing the potential to probe new regions of parameter space of dark matter models are encouraged. On the theoretical and phenomenological side, some groups are devoted to astrophysical aspects such as the dark matter density profile while others explore the signature of dark matter models at colliders, direct and indirect detection experiments. In summary, the Brazilian dark matter community that was born not long ago has grown tremendously in the past years and now plays an important role in the hunt for a dark matter particle., 10 pages, 1 figure

We consider the Singlet Majorana fermion dark matter model, in which the standard model particles interact with the dark sector through the mixing of a singlet scalar and the Higgs boson. In this model both the dark matter and the singlet scalar carry lepton number, the latter being a bilepton. We suppose the existence of a $Z_2$ symmetry, remnant of some high energy local symmetry breaking, that stabilizes the Majorana fermion. We analyzed the parameter space of this model and found that the lepton number symmetry breaking scale, drove by the singlet scalar, is constrained to be within hundreds to thousands of GeV, so as to conform with the observed dark matter relic density. Finally, we address the direct detection and invisible Higgs decay complementarity, confronting our model with recent LUX and LHC constraints, as well as XENON1T prospects., 20 pages, 12 figures

In this work we review the cold dark matter problem in the context of a class of models which are a simple extension of the electroweak standard model, where the gauge symmetry is dictated by the group structure, $SU(3)_c\otimes SU(3)_L\otimes U(1)_X$. This model, in different versions, has been able to address many interesting facts not explained by the standard model. It would be just desirable that the dark matter issue could be contemplated as well, since the problem of the missing matter has become one of the greatest indications of incompleteness of currently established theories describing the known interactions and the cosmological evolution and content of the observed Universe. We do that by pointing out some of the successful steps in this direction and remarking some sources of difficulties concerning their phenomenological and theoretical implementation., 23 pages, 6 figures, references added, footnote included on page 3

We construct a full left-right model for the electroweak interactions based on the $SU(3)_{L}\otimes SU(3)_{R}\otimes U(1)_{X}$ gauge symmetry. The fermion content of the model is such that anomaly cancellation restricts the number of families to be a multiple of three. One of the most important features of the model is the joint presence of three light active neutrinos, three additional neutrinos at keV mass scale, and six heavy ones with masses around\textbf{$10^{11}$} GeV. They form a well-motivated part of the spectrum in the sense they address challenging problems related to neutrino oscillation, warm dark matter, and baryogenesis through leptogenesis., 11 pages. Small corrections and typos fixed. Accepted for publication in PRD

In the original version of the minimal SU(3)_C x SU(3)_L x U(1)_N model the masses of all quarks are correctly obtained by introducing three scalar triplets into the model, meanwhile the lepton mass generation requires the introduction of at least one scalar sextet. In this work we show that this scalar sextet is unable to yield the correct neutrino masses and mixing. In order to solve this puzzle in the most economical way, we evoke an additional Z_3 discrete symmetry, without including this sextet in the scalar spectrum, and propose a truly minimal 3-3-1 model capable of generating the correct masses and mixing of all fermions. Moreover, we show that our proposal leads to naturally light neutrinos with masses in the eV range, obtained with three scalar triplets only. Finally, the so called minimal 3-3-1 model is also in danger due to the presence of undesirable effective operators that lead to proton decay unless they are suppressed by extremely small couplings or, as we choose to employ in this work, are eliminated by some discrete symmetry., 14 pages, no figure, some corrections on the proton decay operators, conclusions unchanged, matches published version in PRD

We add a singlet right handed neutrino plus a charged and a neutral singlet scalars to the standard model. This extension includes a discrete symmetry such that we obtain a heavy sterile neutrino which couples only to the electron and the new scalars. In this sense the singlet neutrino does not mix with ordinary ones and thus has no effect on Big Bang Nucleosynthesis. However, such sterile neutrino can be in equilibrium with electroweak particles in the early Universe due to its couplings to electrons and also because the Higgs boson mixes with the singlet scalars. We obtain that the sterile neutrino constitutes a dark matter candidate and analyze its direct detection in the light of current experiments. Our results show that if such a sterile neutrino is realized in nature, and CDMS-II experiment confirms its positive signal, dark matter demands a rather light Higgs boson with new Physics at some 500 GeV scale., 16 pages, 13 figures, uses axodraw.sty

Recently it has been proposed that the physical spectrum of a vector-like gauge field theory may exhibit an enhanced global symmetry near a chiral/conformal phase transition. The new symmetry is related to the possibility, supported by various investigations, that a parity-doubled spectrum develops as the number of fermions Nf is increased to a critical value above which it is expected that the symmetric phase is restored. We show that parity-doubling together with the associated enhanced global symmetry severely constrains the epsilon terms of the effective Lagrangian involving Goldstone bosons as well as massive spin-1 particles. We extend our analysis to underlying fermions in pseudo-real representations of the gauge group., 22 pages, RevTeX format. Appendix A added. Accepted in Nucl. Phys. B