On the Mass Eigenstate Purity of B^8 Solar Neutrinos

We give a brief report on our recent paper, hep-ph/0601198, in which we calculate the nu_2 mass eigenstate purity of B^8 solar neutrinos as 91 +/- 2 %.Comment: 3 pages, 2 postscript figures, latex, AIP conference style. PANIC 2005 proceeding

Projeto Sócrates: uma experiência de informatização do aprendizado no Instituto de Física

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Can New Colored Particles Illuminate the Higgs?

We analyze the behavior of Higgs to diphoton rate and Higgs gluon-gluon production cross section in minimal extensions of the Standard Model comprising new colored vector-like fermions that do not mix with the ordinary ones. We compare these information with constraints coming from electroweak precision measurements. We compute pair production cross sections for the lightest fermion and discuss the LHC bounds. Finally, we study the phenomenology of possible quarkonium states composed by these new colored fermions.Comment: 18 pages, 7 figures. v2: typos fixed, references added, small improvements mad

Limits on Neutrinophilic Two-Higgs-Doublet Models from Flavor Physics

We derive stringent limits on neutrinophilic two-Higgs-doublet models from low-energy observables after the discovery of the Higgs boson and of the mixing angle $\theta_{13}$. These decays can constrain the plane spanned by $m_{H^\pm}$, the mass of the new charged Higgs, and $v_2$, the vacuum expectation value of the new neutrinophilic scalar doublet. Lepton flavor conserving decays are not able to set meaningful bounds, since they depend strongly on the unknown neutrino absolute mass scale. On the other hand, loop induced lepton flavor violating decays, such as $\mu \to e \gamma$, $\mu \to 3 e$ or $\mu \to e$ in nuclei are currently responsable for the best limits today. If $v_2 \lesssim 1 \, (0.1)$ eV we get $m_{H^\pm} \gtrsim 250 \, (2500)$ GeV at 90% CL. In the foreseen future these limits can improve by at least a factor of 100.Comment: 15 pages, 5 figures, references and comments added, conclusions unchanged, matches version to appear in JHE

(In)Visible signatures of the minimal dark abelian gauge sector

In this paper we study the present and future sensitivities of the rare meson decay facilities KOTO, LHCb and Belle II to a light dark sector of the minimal dark abelian gauge symmetry where a dark Higgs $S$ and a dark photon $Z_D$ have masses $\lesssim 10$ GeV. We have explored the interesting scenario where $S$ can only decay to a pair of $Z_D$'s and so contribute to visible or invisible signatures, depending on the life-time of the latter. Our computations show that these accelerator experiments can access the dark Higgs (mass and scalar mixing) and the dark photon (mass and kinetic mixing) parameters in a complementary way. We have also discussed how the CMS measurement of the SM Higgs total decay width and their limit on the Higgs invisible branching ratio can be used to extend the experimental reach to dark photon masses up to $\sim 10$ GeV, providing at the same time sensitivity to the gauge coupling associated with the broken dark abelian symmetry.Comment: 33 pages, 11 figure