Hidden Physics at the Neutrino Frontier: Tridents, Dark Forces, and Hidden Particles

The unexplained origin of neutrino masses suggests that these neutral and weakly interacting particles might provide a portal to physics beyond the Standard Model. In view of the growing prospects in experimental neutrino physics, we explore new theoretical models and experimental searches that can shed light on the existence of low-scale particles with very small couplings to ordinary matter. Our efforts highlight a vast landscape of models where neutrino physics offers our best chance of discovering such hidden sectors. Along the way, we revisit the Standard Model physics of neutrino trident production with a modern calculation and explore its phenomenology at neutrino facilities. As shown here, this type of rare neutrino scattering process can probe unexplored anomaly-free extensions of the Standard Model with a complementary, and often more powerful, search strategy to to the well-known searches in neutrino-electron scattering. As to new models, we propose a novel neutrino mass model resembling the inverse seesaw, where neutrino mixing stands as the most prominent portal to dark sectors and dark matter. In our dark neutrino model, neutrino masses are generated radiatively, with the vector, scalar, and neutrino phenomenology displaying an unique interplay. Later, we devise new methods to search for these dark neutrinos using neutrino-electron scattering data, aiming to discriminate among new physics explanations of the MiniBooNE anomalous results. Finally, we discuss light and heavy conventional sterile neutrinos in the context of $\nu$STORM, an entry-level neutrino factory for precision neutrino physics

Pion decay constraints on exotic 17 MeV vector bosons

We derive constraints on the couplings of light vector particles to all first-generation Standard Model fermions using leptonic decays of the charged pion, $\pi^+\to e^+ \nu_e X_\mu$. In models where the net charge to which $X_\mu$ couples to is not conserved, no lepton helicity flip is required for the decay to happen, enhancing the decay rate by factors of ${O}(m_\pi^4/m_e^2m_X^2)$. A past search at the SINDRUM-I spectrometer severely constrains this possibility. In the context of the hypothesized $17$ MeV particle proposed to explain anomalous $^8$Be, $^4$He, and $^{12}$C nuclear transitions claimed by the ATOMKI experiment, this limit rules out vector-boson explanations and poses strong limits on axial-vector ones.Comment: 10 pages, 5 figure

New physics in multi-electron muon decays

We study the exotic muon decays with five charged tracks in the final state. First, we investigate the Standard Model rate for $\mu^+ \to 3e^+\,2e^-\,2\nu$ ($B = 4.0\times 10^{-10})$ and find that the Mu3e experiment should have tens to hundreds of signal events per $10^{15}$ $\mu^+$ decays, depending on the signal selection strategy. We then turn to a neutrinoless $\mu^+ \to 3e^+\,2e^-$ decay that may arise in new-physics models with lepton-flavor-violating effective operators involving a dark Higgs $h_d$. Following its production in $\mu^+ \to e^+ h_d$ decays, the dark Higgs can undergo a decay cascade to two $e^+e^-$ pairs through two dark photons, $h_d \to \gamma_d \gamma_d \to 2(e^+e^-)$. We show that a $\mu^+ \to 3e^+\,2e^-$ search at the Mu3e experiment, with potential sensitivity to the branching ratio at the $O(10^{-12})$ level or below, can explore new regions of parameter space and new physics scales as high as $\Lambda \sim 10^{15}$ GeV.Comment: 20 pages, 7 figure

Proteção de dados pessoais na internet: a necessidade de lei específica no ordenamento jurídico brasileiro

TCC(graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Jurídicas. Direito.A proteção aos dados pessoais é tema muito discutido na atualidade. Ela abarca desde direitos fundamentais como a proteção à intimidade e a vida privada e avança até ao seu entendimento de um direito autônomo. Enfrenta questões inéditas acerca de seu uso, decorrentes da introdução de novas tecnologias e da internet, além da mudança de paradigmas nas relações sociais e na economia. O objetivo deste trabalho é demonstrar a necessidade urgente de resguardar a privacidade e regulamentar o uso dos dados pessoais colhidos na internet através de lei específica. Nesse intuito, a partir de pesquisa bibliográfica, e documental, por meio de notícias, artigos e relatórios realizados acerca do tema, o trabalho trata, num primeiro tópico acerca dos conceitos de privacidade e intimidade e da proteção de dados pessoais como um direito autônomo e fundamental, para, num segundo tópico, demonstrar as diversas utilizações dos dados coleados. Por fim, o terceiro tópico aborda o Regulamento 2016/679 da União Europeia, o Marco Civil da Internet no Brasil, o Projeto de Lei n° 5.276/2016, o Projeto de Lei n° 330/2013, Projeto de Lei n° 4.060/2012, e o Projeto de Lei n° 53/2018

Bicycle rack

A bicycle rack designed to support and lock a bicycle by the bicycle\u27s front center post. Support and lock brackets for individual bicycles are horizontally disposed fork arrangements formed by two joined U-shaped members. Oppositely extending locking brackets allow pairs of bicycles to be conveniently placed along a series of evenly spaced posts and cross-bars