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  • Publication
    Erratum: QCD corrections and long-range mechanisms of neutrinoless double beta decay (Physical Review D (2016) 94 (096014)
    (2018-05-01) ;
    M. González
    ;
    M. Hirsch
    ;
    Recently it has been demonstrated that QCD corrections are numerically important for short-range mechanisms (SRM) of neutrinoless double beta decay (0νββ) mediated by heavy particle exchange. This is due to the effect of color mismatch for certain effective operators, which leads to mixing between different operators with vastly different nuclear matrix elements (NMEs). In this note we analyze the QCD corrections for long-range mechanisms (LRM), due to diagrams with light-neutrino exchange between a Standard Model (V-A)×(V-A) and a beyond the SM lepton number violating vertex. We argue that in contrast to the SRM in the LRM case, there is no operator mixing from color-mismatched operators. This is due to a combined effect of the nuclear short-range correlations and color invariance. As a result, the QCD corrections to the LRM amount to an effect no more than 60%, depending on the operator in question. Although less crucial, taken into account QCD running makes theoretical predictions for 0νββ-decay more robust also for LRM diagrams. We derive the current experimental constraints on the Wilson coefficients for all LRM effective operators.
  • Publication
    A common framework for fermion mass hierarchy, leptogenesis and dark matter
    (2024-08-01)
    Arbeláez, Carolina
    ;
    ; ;
    Contreras, Patricio Escalona
    ;
    K. N, Vishnudath
    ;
    In this work, we explore an extension of the Standard Model designed to elucidate the fermion mass hierarchy, account for the dark matter relic abundance, and explain the observed matter-antimatter asymmetry in the universe. Beyond the Standard Model particle content, our model introduces additional scalars and fermions. Notably, the light active neutrinos and the first two generations of charged fermions acquire masses at the one-loop level. The model accommodates successful low-scale leptogenesis, permitting the mass of the decaying heavy right-handed neutrino to be as low as 10 TeV. We conduct a detailed analysis of the dark matter phenomenology and explore various interesting phenomenological implications. These include charged lepton flavor violation, muon and electron anomalous magnetic moments, constraints arising from electroweak precision observables, and implications for collider experiments.
  • Publication
    Neutrino predictions from a left-right symmetric flavored extension of the standard model
    (2019-02-01) ;
    Valle, José W.F.
    ;
    ;
    Vaquera-Araujo, C. A.
    Abstract We propose a left-right symmetric electroweak extension of the Standard Model based on the Δ (27) family symmetry. The masses of all electrically charged Standard Model fermions lighter than the top quark are induced by a Universal Seesaw mechanism mediated by exotic fermions. The top quark is the only Standard Model fermion to get mass directly from a tree level renormalizable Yukawa interaction, while neutrinos are unique in that they get calculable radiative masses through a low-scale seesaw mechanism. The scheme has generalized μ − τ symmetry and leads to a restricted range of neutrino oscillations parameters, with a nonzero neutrinoless double beta decay amplitude lying at the upper ranges generically associated to normal and inverted neutrino mass ordering.
  • Publication
    A renormalizable left-right symmetric model with low scale seesaw mechanisms
    We propose a low scale renormalizable left-right symmetric theory that successfully explains the observed SM fermion mass hierarchy, the tiny values for the light active neutrino masses and is consistent with the lepton and baryon asymmetries of the Universe, the muon and electron anomalous magnetic moments as well as with the constraints arising from the meson oscillations. In the proposed model the top and exotic quarks obtain masses at tree level, whereas the masses of the bottom, charm and strange quarks, tau and muon leptons are generated from a tree level Universal Seesaw mechanism, thanks to their mixings with the charged exotic vector like fermions. The masses for the first generation SM charged fermions arise from a radiative seesaw mechanism at one loop level, mediated by charged vector like fermions and electrically neutral scalars. The light active neutrino masses are produced from a one-loop level inverse seesaw mechanism mediated by electrically neutral scalar singlets and right handed Majorana neutrinos. Our model is also consistent with the experimental constraints arising from the Higgs diphoton decay rate as well as with the constraints arising from charged lepton flavor violation. We also discuss the and heavy scalar production at a proton-proton collider.
  • Publication
    Automatic generation of roadmap for e-government implementation
    (2010-11-05) ;
    Pantoja, Daniel
    ;
    Valdés, Gonzalo
    E-government research deals with ‘wicked’ problems that require multidisciplinary approaches to gain a full understanding. One of the main challenges of e-government is to induce change in the structure of public organizations to realize its full potential. This paper investigates e-government induced change using two complementary theoretical lenses applied to an egovernment case study. We use organization theories to explore aspects of organizational structure that may change when implementating e-government and structuration theory to investigate how these aspects are affected by human action within its social structure. This combination allows us to investigate the discrepancy between the ambitions of e-government induced change and the actual changes accomplished in practice. Our analysis shows that using these two frames gives us better insight into the thorny subject of e-government than using a single theory. Further research should look into how these theories can be used to deepen our knowledge of e-government.