4,771 research outputs found

    Lepton-Flavour-Violation in SUSY Models with and without R-parity

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    We discuss Lepton-Flavour-Violating phenomena such as μ→eγ\mu \to e \gamma, μ→eee\mu \to eee, and μ→e\mu \to e conversion in nuclei in SUSY models with and without R-parity. We stress that experimental searches for all the LFV processes are important to distinguish between the different models.Comment: 4 pages, talk given at 8th International Workshop on Deep Inelastic Scattering and QCD (DIS 2000), Liverpool, England, 25-30 Apr 200

    Michel parameters for τ\tau decays τ→lννˉ (l=e, μ)\tau \rightarrow l\nu\bar{\nu}~(l=e,~\mu) in a general two Higgs doublet model with μ−τ\mu-\tau flavor violation

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    In a general two Higgs doublet model (2HDM), the anomaly of muon anomalous magnetic moment (muon g-2) can be explained by μ−τ\mu-\tau flavor violating Yukawa couplings, motivated by the recent CMS excess in Higgs boson decay h→μτh\rightarrow \mu \tau. We study Michel parameters for τ\tau decays τ→lννˉ (l=e, μ)\tau \rightarrow l \nu \bar{\nu}~(l=e,~\mu) in the 2HDM with the lepton flavor violation, and show that they can be sensitive to the flavor structure as well as the Lorentz and chiral structures of the model. We find that the correction to the Michel parameter ξμ\xi_\mu in τ→μννˉ\tau \rightarrow \mu \nu\bar{\nu} is correlated to the contribution to the muon g-2, and it can be as large as 10−4−10−210^{-4}-10^{-2} in the parameter region where the μ−τ\mu-\tau flavor violating Yukawa couplings explain the muon g-2 anomaly. Therefore the precision measurement of the Michel parameter at the level of 10−4−10−210^{-4}-10^{-2} would significantly probe the interesting parameter space for the solution to the muon g-2 anomaly.Comment: 16 pages, 2 figure

    New physics for muon anomalous magnetic moment and its electroweak precision analysis

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    About 3 sigma deviation from the standard model prediction of muon anomalous magnetic moment (muon g-2) has been reported. We consider new physics beyond the standard model which has new Yukawa interactions with muon. We compute new contributions to muon g-2 and corrections to electroweak observables, and show the consistent region of parameter space. We find that in a simple model where the chirality flip of muon occurs only in the external muon line in one-loop muon g-2 diagrams, it is necessary to introduce the relatively large new Yukawa coupling and the electroweak scale new particles. On the other hand, in a model where the chirality flip can occur in the internal fermion line of one loop muon g-2 diagrams, we can obtain favorable g-2 contributions without large Yukawa coupling, and they are consistent with the precision electroweak observables. Finally, we discuss effects of new particles for muon g-2 on the Higgs boson decay h to 2 photons and direct productions of these particles at the LHC experiment.Comment: 31 pages, 20 figure

    Lepton-flavor-violating Higgs decay h→μτh \to \mu\tau and muon anomalous magnetic moment in a general two Higgs doublet model

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    A two Higgs doublet model (2HDM) is one of the minimal extensions of the Standard Model (SM), and it is well-known that the general setup predicts the flavor-violating phenomena, mediated by neutral Higgs interactions. Recently the CMS collaboration has reported an excess of the lepton-flavor-violating Higgs decay in h→μτh \rightarrow \mu \tau channel with a significance of 2.5 σ \sigma. We investigate the CMS excess in a general 2HDM with tree-level Flavor Changing Neutral Currents (FCNCs), and discuss its impact on the other physical observations. Especially, we see that the FCNCs relevant to the excess can enhance the neutral Higgs contributions to the muon anomalous magnetic moment, and can resolve the discrepancy between the measured value and the SM prediction. We also find that the couplings to be consistent with the muon g-2 anomaly as well as the CMS excess in h→μτh\rightarrow \mu\tau predict the sizable rate of τ→μγ \tau \rightarrow \mu \gamma, which is within the reach of future B factory.Comment: 6 pages, 3 figures, revised Fig.3, corrected Eq. (12), added references, accepted for publication in JHE

    A Gauge Mediation Model of Dynamical Supersymmetry Breaking without Color Instability

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    We construct a gauge mediation model of dynamical supersymmetry breaking (DSB) based on a vector-like gauge theory, in which there is a unique color-preserving true vacuum. The DSB scale Λ/4π\Lambda/4\pi turns out to be as high as Λ/4π≃108−9GeV\Lambda/4\pi \simeq 10^{8-9} GeV, since the transmission of the DSB effects to the standard model sector is completed through much higher loops. This model is perfectly natural and phenomenologically consistent. We also stress that the dangerous D-term problem for the messenger U(1)_m is automatically solved by a charge conjugation symmetry in the vector-like gauge theory.Comment: 11 pages, Late
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