1,026 research outputs found

    Port-Hamiltonian modeling for soft-finger manipulation

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    In this paper, we present a port-Hamiltonian model of a multi-fingered robotic hand, with soft-pads, while grasping and manipulating an object. The algebraic constraints of the interconnected systems are represented by a geometric object, called Dirac structure. This provides a powerful way to describe the non-contact to contact transition and contact viscoelasticity, by using the concepts of energy flows and power preserving interconnections. Using the port based model, an Intrinsically Passive Controller (IPC) is used to control the internal forces. Simulation results validate the model and demonstrate the effectiveness of the port-based approach

    Impact of QED corrections to Higgs decay into four leptons at the LHC

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    At the LHC a precise measurement of the Higgs boson mass (if discovered), at the level of 0.1-1%, will be possible through the channel g g --> H --> 4l for a wide range of Higgs mass values. To match such an accuracy, the systematic effects induced by QED corrections need to be investigated. In the present study the calculation of O(alpha) and higher order QED corrections is illustrated as well as their impact on the Higgs mass determination, once realistic event selection criteria for charged leptons and photons are considered.Comment: 5 pages, 5 figures, 1 table. Presented at HEP2005 July 21st-27th, 2005, Lisboa, Portugal and at RADCOR 2005, Shonan Village, October 2nd-7th, 2005, Japa

    Photon pair production at flavour factories with per mille accuracy

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    We present a high-precision QED calculation, with 0.1% theoretical accuracy, of two photon production in e+ee^+ e^- annihilation, as required by more and more accurate luminosity monitoring at flavour factories. The accuracy of the approach, which is based on the matching of exact next-to-leading order corrections with a QED Parton Shower algorithm, is demonstrated through a detailed analysis of the impact of the various sources of radiative corrections to the experimentally relevant observables. The calculation is implemented in the latest version of the event generator BabaYaga, available for precision simulations of photon pair production at e+ee^+ e^- colliders of moderately high energies.Comment: 11 pages, 5 figures, 1 tabl

    The Electoral Consequences of Large Fiscal Adjustments

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    The conventional wisdom regarding the political consequences of large reductions of budget deficits is that they are very costly for the governments which implement them: they are punished by voters at the following elections. In the present paper, instead, we find no evidence that governments which quickly reduce budget deficits are systematically voted out of office in a sample of 19 OECD countries from 1975 to 2008. We also take into consideration issues of reverse causality, namely the possibility that only "strong and popular" governments can implement fiscal adjustments and thus they are not voted out of office "despite" having reduced the deficits. In the end we conclude that many governments can reduce deficits avoiding an electoral defeat.

    Full one-loop electroweak corrections to e+e- to 3 jets at linear colliders

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    We describe the impact of the full one-loop electroweak terms of O(alpha_s alpha_EM^3) entering the electron-positron into three-jet cross-section from sqrt(s)=M_Z to TeV scale energies. We include both factorisable and non-factorisable virtual corrections and photon bremsstrahlung. Their importance for the measurement of alpha_S from jet rates and shape variables is explained qualitatively and illustrated quantitatively, also in presence of b-tagging.Comment: 6 pages, to appear in the proceedings of the workshop "LC09 -- e+e- Physics at the TeV scale and the Dark Matter Connection", 21-24 September 2009, Perugia (Italy). Minor corrections, references added

    Matrix elements and Parton Shower in the event generator BABAYAGA

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    A new version of the event generator BABAYAGA is presented, which is based on an original matching of the Parton Shower approach with the complete exact O(alpha) matrix element for the inclusion of the QED radiative corrections to the Bhabha process at flavour factories. The theoretical accuracy of the improved generator is conservatively estimated to be 0.2%, by comparison with independent calculations. The generator is a useful tool for precise luminosity determination at flavour factories, for center of mass energies below 10 GeV.Comment: 4 pages, 2 figures. To appear in the proceedings of the International Workshop e+ e- Collisions from phi to psi, Novosibirsk (Russia), 27 Feb - 2 Mar 200
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