94 research outputs found

    Probing Leptonic Models at the LHC

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    Models of neutrino mass generation provide well motivated scenarios of Beyond-the-Standard-Model physics. The synergy between low energy and high energy LHC searches facilitates an effective approach to rule out, constrain or ideally pinpoint such models. In this proceedings report, we provide a brief overview of scenarios where searches at the LHC can help determine the mechanism of light neutrino masses and potentially falsify baryogenesis mechanisms.Comment: Talk presented at CIPANP2015. 9 pages, 3 figure

    Lepton Flavour Violation and theta(13) in Minimal Resonant Leptogenesis

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    We study the impact of minimal non-supersymmetric models of resonant leptogenesis on charged lepton flavour violation and the neutrino mixing angle theta(13). Possible low-scale flavour realisations of resonant tau-, mu- and e-leptogenesis provide very distinct and predictive frameworks to explain the observed baryon asymmetry in the Universe by sphaleron conversion of an individual tau-, mu- and e-lepton-number asymmetry which gets resonantly enhanced via out-of-equilibrium decays of nearly degenerate heavy Majorana neutrinos. Based on approximate flavour symmetries, we construct viable scenarios of resonant tau-, mu- and e-leptogenesis compatible with universal right-handed neutrino masses at the GUT scale, where the required heavy-neutrino mass splittings are generated radiatively. The heavy Majorana neutrinos in such scenarios can be as light as 100 GeV and their couplings to two of the charged leptons may be large. In particular, we explicitly demonstrate the compelling role that the three heavy Majorana neutrinos play, in order to obtain successful leptogenesis and experimentally testable rates for lepton flavour violating processes, such as mu --> e gamma and mu --> e conversion in nuclei.Comment: 40 pages, 9 figures, PRD versio

    Minimal Resonant Leptogenesis and Lepton Flavour Violation

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    We discuss minimal non-supersymmetric models of resonant leptogenesis, based on an approximate flavour symmetries. As an illustrative example, we consider a resonant tau-leptogenesis model, compatible with universal right-handed neutrino masses at the GUT scale, where the required heavy-neutrino mass splittings are generated radiatively. In particular, we explicitly demonstrate, how a minimum number of three heavy Majorana neutrinos is needed, in order to obtain successful leptogenesis and experimentally testable rates for processes of lepton flavour violation, such as mu --> e gamma and mu --> e conversion in nuclei.Comment: 7 pages, invited talk given by AP at the international conference GUT2012, Kyoto, Japan, 15-17 March 201

    Dark Matter and Lepton Flavour Violation in a Hybrid Neutrino Mass Model

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    We describe a hybrid model in which the light neutrino mass matrix receives both tree-level seesaw and loop-induced contributions. An additional U(1) gauge symmetry is used to stabilize the lightest right-handed neutrino as the Dark Matter candidate. After fitting the experimental neutrino data, we analyze and correlate the phenomenological consequences of the model, namely its impact on electroweak precision measurements, the Dark Matter relic abundance, lepton flavour violating rare decays and neutrinoless double beta decay. We find that natural realizations of the model characterized by large Yukawa couplings are compatible with and close to the current experimental limits.Comment: 25 pages, 9 figures. V2: references added, typos corrected, version accepted by JHE

    Heavy neutrino production via Zβ€²Z' at the lifetime frontier

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    We investigate the pair production of right-handed neutrinos from the decay of an additional neutral Zβ€²Z^{\prime} boson in the gauged Bβˆ’LB-L model. Taking into account current constraints on the Zβ€²Z^{\prime} mass and the associated gauge coupling g1β€²g_{1}^{\prime}, we analyse the sensitivity of proposed experiments at the lifetime frontier, FASER 2, CODEX-b, MATHUSLA as well as a hypothetical version of the MAPP detector to a long lived heavy neutrino NN originating in the decays of the Zβ€²Z^{\prime}. We further complement this study with determining the reach of LHCb and a CMS-type detector for the high-luminosity LHC run. We demonstrate that in a background free scenario with g1β€²=10βˆ’3g_1^\prime = 10^{-3} near the current limit, FASER 2 is sensitive to the active-sterile neutrino mixing down to VΞΌNβ‰ˆ10βˆ’4V_{\mu N} \approx 10^{-4}, while a reach of VΞΌNβ‰ˆ10βˆ’5V_{\mu N} \approx 10^{-5} can be obtained for CODEX-b and LHCb, in a mass regime of mNβ‰ˆ5βˆ’20m_N \approx 5-20 GeV and mZβ€²β‰ˆ20βˆ’70m_{Z^{\prime}} \approx 20-70 GeV. Finally, MATHUSLA can probe VΞΌNβ‰ˆ10βˆ’7V_{\mu N} \approx 10^{-7} and cover the mixing regime expected in a canonical seesaw scenario of light neutrino mass generation.Comment: 20 pages, 6 figures, matches published versio

    Long-lived Heavy Neutrinos from Higgs Decays

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    We investigate the pair-production of right-handed neutrinos via the Standard Model (SM) Higgs boson in a gauged Bβˆ’LB-L model. The right-handed neutrinos with a mass of few tens of GeV generating viable light neutrino masses via the seesaw mechanism naturally exhibit displaced vertices and distinctive signatures at the LHC and proposed lepton colliders. The production rate of the right-handed neutrinos depends on the mixing between the SM Higgs and the exotic Higgs associated with the Bβˆ’LB-L breaking, whereas their decay length depends on the active-sterile neutrino mixing. We focus on the displaced leptonic final states arising from such a process, and analyze the sensitivity reach of the LHC and proposed lepton colliders in probing the active-sterile neutrino mixing. We show that mixing to muons as small as VΞΌNβ‰ˆ10βˆ’7V_{\mu N} \approx 10^{-7} can be probed at the LHC with 100 fbβˆ’1^{-1} and at proposed lepton colliders with 5000 fbβˆ’1^{-1}. The future high luminosity run at LHC and the proposed MATHUSLA detector may further improve this reach by an order of magnitude.Comment: 23 pages, 9 figures, matches published versio

    Compressed and Split Spectra in Minimal SUSY SO(10)

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    The non-observation of supersymmetric signatures in searches at the Large Hadron Collider strongly constrains minimal supersymmetric models like the CMSSM. We explore the consequences on the SUSY particle spectrum in a minimal SO(10) with large D-terms and non-universal gaugino masses at the GUT scale. This changes the sparticle spectrum in a testable way and for example can sufficiently split the coloured and non-coloured sectors. The splitting provided by use of the SO(10) D-terms can be exploited to obtain light first generation sleptons or third generation squarks, the latter corresponding to a compressed spectrum scenario.Comment: 35 pages, 10 figures, published versio
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