1,311 research outputs found

    Top quark chromomagnetic dipole moment in the littlest Higgs model with T-parity

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    The littlest Higgs model with T-parity, which is called LHTLHT model, predicts the existence of the new particles, such as heavy top quark, heavy gauge bosons, and mirror fermions. We calculate the one-loop contributions of these new particles to the top quark chromomagnetic dipole moment (CMDM)(CMDM) ΔK\Delta K. We find that the contribution of the LHTLHT model is one order of magnitude smaller than the standard model prediction value.Comment: latex files, 12 pages, 3 figure

    On machine vision and photographic imagination

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    Indirect tests of the Randall-Sundrum model

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    I present phenomenological implications of the Randall-Sundrum model for indirect searches, specifically a selection of flavor observables and Higgs-related collider searches. I review the interplay of constraints from CP violation in flavor physics, possible effects in rare decays, and model-specific protection mechanisms. Deviations in the Higgs couplings to fermions and, at one-loop, to gluons are unexpectedly strong and lead to strong modifications in Higgs searches.Comment: 8 pages, 6 figures; Talk given at Discrete '10: Symposium on Prospects in the Physics of Discrete Symmetries, Rome, Italy, 6-11 Dec 201

    Making Data Visualizations, Contesting Security:Digital Humanities Meet International Relations

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    This article brings debates about data visualization in digital humanities in conversation with critical security studies and international relations. Building on feminist approaches in digital humanities, we explore the potential and limitations of data visualization as a critical method for research on (in)security. We unpack three aspects of making data visualizations by specifying "making"in this context as working, orienting, and critiquing. Making data visualizations as a methodological device is oriented by questions about the contestation of security and orients research by provoking new questions about practices of critique. Empirically, we situate data visualizations within British parliamentary debates about the Government Communications Headquarters (GCHQ), the UK's signals intelligence agency, which has garnered much public attention in the wake of the Snowden disclosures of transnational mass surveillance. We argue that data visualization in the parliamentary archive can destabilize dominant understandings of security, problematize narratives of security actors and oversight, and attend to the uneven presence of critique and contestation within and beyond parliamentary debates.</p

    Electroweak and Flavour Structure of a Warped Extra Dimension with Custodial Protection

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    We present the electroweak and flavour structure of a model with a warped extra dimension and the bulk gauge group SU(3) x SU(2)_L x SU(2)_R x P_LR x U(1)_X. The presence of SU(2)_R implies an unbroken custodial symmetry in the Higgs system allowing to eliminate large contributions to the T parameter, whereas the P_LR symmetry and the enlarged fermion representations provide a custodial symmetry for flavour diagonal and flavour changing couplings of the SM Z boson to left-handed down-type quarks. We diagonalise analytically the mass matrices of charged and neutral gauge bosons including the first KK modes. We present the mass matrices for quarks including heavy KK modes and discuss the neutral and charged currents involving light and heavy fields. We give the corresponding complete set of Feynman rules in the unitary gauge.Comment: 74 pages, 2 figures. clarifying comments and references added, version to be published in JHE

    On CP Asymmetries in Two-, Three- and Four-Body D Decays

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    Indirect and direct CP violations have been established in K_L and B_d decays. They have been found in two-body decay channels -- with the exception of K_L to pi^+ pi^- e^+ e^- transitions. Evidence for direct CP asymmetry has just appeared in LHCb data on A_{CP}(D^0 to K^+ K^-) - A_{CP}(D^0 to pi^+ pi^-) with 3.5 sigma significance. Manifestations of New Dynamics (ND) can appear in CP asymmetries just below experimental bounds. We discuss D^{\pm}_{(s)}, D^0/\bar D^0 and D_L/D_S transitions to 2-, 3- and 4-body final states with a comment on predictions for inclusive vs. exclusive CP asymmetries. In particular we discuss T asymmetries in D to h_1 h_2 l^+ l^- in analogy with K_L to pi^+ pi^- e^+ e^- transitions due to interference between M1, internal bremsstrahlung and possible E1 amplitudes. Such an effect depends on the strength of CP violation originating from the ND -- as discussed here for Little Higgs Models with T parity and non-minimal Higgs sectors -- but also in the interferences between these amplitudes even in the Standard Model (SM). More general lessons can be learnt for T asymmetries in non-leptonic D decays like D to h_1h_2 h_3 h_4. Such manifestations of ND can be tested at LHCb and other Super-Flavour Factories like the projects at KEK near Tokyo and at Tor Vergata/Frascati near Rome.Comment: 27 pages, 6 figures. Revised with current results from LHCb and HFAG and further interpretation

    Symmetries and Asymmetries of B -> K* mu+ mu- Decays in the Standard Model and Beyond

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    The rare decay B -> K* (-> K pi) mu+ mu- is regarded as one of the crucial channels for B physics as the polarization of the K* allows a precise angular reconstruction resulting in many observables that offer new important tests of the Standard Model and its extensions. These angular observables can be expressed in terms of CP-conserving and CP-violating quantities which we study in terms of the full form factors calculated from QCD sum rules on the light-cone, including QCD factorization corrections. We investigate all observables in the context of the Standard Model and various New Physics models, in particular the Littlest Higgs model with T-parity and various MSSM scenarios, identifying those observables with small to moderate dependence on hadronic quantities and large impact of New Physics. One important result of our studies is that new CP-violating phases will produce clean signals in CP-violating asymmetries. We also identify a number of correlations between various observables which will allow a clear distinction between different New Physics scenarios.Comment: 56 pages, 18 figures, 14 tables. v5: Missing factor in eqs. (3.31-32) and fig. 6 corrected. Minor misprints in eq. (2.10) and table A corrected. Conclusions unchange

    Response Analysis and Comparison of a Spar-Type Floating Offshore Wind Turbine and an Onshore Wind Turbine under Blade Pitch Controller Faults

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    This paper analyses the effects of three pitch controller faults on the responses of an onshore wind turbine and a spar-type offshore floating wind turbine. These faults include: a stuck blade pitch actuator, a fixed value fault and a bias fault of the blade pitch sensor. The faults are modeled in the controller dynamic link library and a short-term extreme response analysis is performed using the HAWC2 simulation tool. The main objectives of this paper are to investigate how different faults affect the performance of wind turbines for condition monitoring purposes and which differences exist in the structural responses between onshore and offshore floating wind turbines. Statistical analysis of the selected response parameters are conducted using the six 1-hour stochastic samples for each load case. For condition monitoring purpose, the effects of faults on the responses at different wind speeds and fault amplitudes are investigated by comparing the same response under normal operation. The severities of the individual faults are categorized by the extreme values of structural loads and the structural components are sorted based on the magnitude of the fault effects on the extreme values. The pitch sensor fixed value fault is determined as the most severe fault case and the shaft appears as the structural component that experiences the highest risk. The effects of fault conditions on the offshore floating and the onshore wind turbines are compared to investigate the potential differences. The results show that faults cause more damage to the tower and the yaw bearing for the onshore wind turbine and more damage to the shaft for the offshore floating wind turbine
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