8,067 research outputs found

    Muon Anomalous Magnetic Moment and mu -> e gamma in B-L Model with Inverse Seesaw

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    We study the anomalous magnetic moment of the muon, a_\mu, and lepton flavor violating decay \mu -> e \gamma in TeV scale B-L extension of the Standard Model (SM) with inverse seesaw mechanism. We show that the B-L contributions to a_\mu are severely constrained, therefore the SM contribution remains intact. We also emphasize that the current experimental limit of BR(\mu -> e \gamma) can be satisfied for a wide range of parameter space and it can be within the reach of MEG experiment.Comment: 10 pages, 4 Figure

    Constraining supersymmetric models from B_d - B-bar_d mixing and the B_d --> J/psi K_S asymmetry

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    We analyze the chargino contributions to B_d - B-bar_d mixing and CP asymmetry of the B_d --> J/psi K_S decay, in the framework of the mass insertion approximation. We derive model independent bounds on the relevant mass insertions. Moreover, we study these contributions in supersymmetric models with minimal flavor violation, Hermitian flavor structure, and small CP violating phases and universal strength Yukawa couplings. We show that in supersymmetric models with large flavor mixing, the observed values of sin(2 beta) may be entirely due to the chargino-up-squark loops.Comment: 22 pages, 1 figure, minor corrections, version to appear in Phys. Rev.

    Exact Analysis of Scaling and Dominant Attractors Beyond the Exponential Potential

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    By considering the potential parameter Γ\Gamma as a function of another potential parameter λ\lambda[47], We successfully extend the analysis of two-dimensional autonomous dynamical system of quintessence scalar field model to the analysis of three-dimension, which makes us be able to research the critical points of a large number of potentials beyond the exponential potential exactly. We find that there are ten critical points in all, three points P3,5,6P_{3, 5, 6}} are general points which are possessed by all quintessence models regardless of the form of potentials and the rest points are closely connected to the concrete potentials. It is quite surprising that, apart from the exponential potential, there are a large number of potentials which can give the scaling solution when the function f(λ)(=Γ(λ)1)f(\lambda)(=\Gamma(\lambda)-1) equals zero for one or some values of λ\lambda_{*} and if the parameter λ\lambda_{*} also satisfies the condition Eq.(16) or Eq.(17) at the same time. We give the differential equations to derive these potentials V(ϕ)V(\phi) from f(λ)f(\lambda). We also find that, if some conditions are satisfied, the de-Sitter-like dominant point P4P_4 and the scaling solution point P9P_9(or P10P_{10}) can be stable simultaneously but P9P_9 and P10P_{10} can not be stable simultaneity. Although we survey scaling solutions beyond the exponential potential for ordinary quintessence models in standard general relativity, this method can be applied to other extensively scaling solution models studied in literature[46] including coupled quintessence, (coupled-)phantom scalar field, k-essence and even beyond the general relativity case H2ρTnH^2 \propto\rho_T^n. we also discuss the disadvantage of our approach.Comment: 16 pages,no figure, this new revision has taken the suggestions from CQG referees and has been accepted for publication in Classical and Quantum Gravit

    Human Arm simulation for interactive constrained environment design

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    During the conceptual and prototype design stage of an industrial product, it is crucial to take assembly/disassembly and maintenance operations in advance. A well-designed system should enable relatively easy access of operating manipulators in the constrained environment and reduce musculoskeletal disorder risks for those manual handling operations. Trajectory planning comes up as an important issue for those assembly and maintenance operations under a constrained environment, since it determines the accessibility and the other ergonomics issues, such as muscle effort and its related fatigue. In this paper, a customer-oriented interactive approach is proposed to partially solve ergonomic related issues encountered during the design stage under a constrained system for the operator's convenience. Based on a single objective optimization method, trajectory planning for different operators could be generated automatically. Meanwhile, a motion capture based method assists the operator to guide the trajectory planning interactively when either a local minimum is encountered within the single objective optimization or the operator prefers guiding the virtual human manually. Besides that, a physical engine is integrated into this approach to provide physically realistic simulation in real time manner, so that collision free path and related dynamic information could be computed to determine further muscle fatigue and accessibility of a product designComment: International Journal on Interactive Design and Manufacturing (IJIDeM) (2012) 1-12. arXiv admin note: substantial text overlap with arXiv:1012.432

    Bounds on New Physics from B -> V1 V2 Decays

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    We consider the possibility that physics beyond the standard model contributes to the decays B -> V1 V2, where V1 and V2 are vector mesons. We show that a time-dependent angular analysis of B -> V1 V2 decays provides many tests for this new physics (NP). Furthermore, although one cannot solve for the NP parameters, we show that this angular analysis allows one to put bounds on these parameters. This can be useful in estimating the scale of NP, and can tell us whether any NP found directly at future high-energy colliders can be responsible for effects seen in B -> V1 V2 decays.Comment: 23 pages, plain LaTeX, 5 figures (included

    Closed-Loop Perching and Spatial Guidance Laws for Bio-Inspired Articulated Wing MAV

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    This paper presents the underlying theoretical developments and successful experimental demonstrations of perching of an aerial robot. The open-loop lateral-directional dynamics of the robot are inherently unstable because it lacks a vertical tail for agility, similar to birds. A unique feature of this robot is that it uses wing articulation for controlling the flight path angle as well as the heading. New guidance algorithms with guaranteed stability are obtained by rewriting the flight dynamic equations in the spatial domain rather than as functions of time, after which dynamic inversion is employed. It is shown that nonlinear dynamic inversion naturally leads to proportional-integral-derivative (PID) controllers, thereby providing an exact method for tuning the gains. The effectiveness of the proposed bio-inspired robot design and its novel closed-loop perching controller has been successfully demonstrated with perched landings on a human hand

    Phase Synchronization Control of Robotic Networks on Periodic Ellipses with Adaptive Network Topologies

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    This paper presents a novel formation control method for a large number of robots or vehicles described by Euler-Lagrange (EL) systems moving in elliptical orbits. A new coordinate transformation method for phase synchronization of networked EL systems in elliptical trajectories is introduced to define desired formation patterns. The proposed phase synchronization controller synchronizes the motions of agents, thereby yielding a smaller synchronization error than an uncoupled control law in the presence of bounded disturbances. A complex time-varying and switching network topology, constructed by the adaptive graph Laplacian matrix, relaxes the standard requirement of consensus stability, even permitting stabilization on an arbitrary unbalanced graph. The proofs of stability are constructed by robust contraction analysis, a relatively new nonlinear stability tool. An example of reconfiguring swarms of spacecraft in Low Earth Orbit shows the effectiveness of the proposed phase synchronization controller for a large number of complex EL systems moving in elliptical orbits

    Two-Dimensional Infrared Spectroscopy of Antiparallel β-Sheet Secondary Structure

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    We investigate the sensitivity of femtosecond Fourier transform two-dimensional infrared spectroscopy to protein secondary structure with a study of antiparallel β-sheets. The results show that 2D IR spectroscopy is more sensitive to structural differences between proteins than traditional infrared spectroscopy, providing an observable that allows comparison to quantitative models of protein vibrational spectroscopy. 2D IR correlation spectra of the amide I region of poly-L-lysine, concanavalin A, ribonuclease A, and lysozyme show cross-peaks between the IR-active transitions that are characteristic of amide I couplings for polypeptides in antiparallel hydrogen-bonding registry. For poly-L-lysine, the 2D IR spectrum contains the eight-peak structure expected for two dominant vibrations of an extended, ordered antiparallel β-sheet. In the proteins with antiparallel β-sheets, interference effects between the diagonal and cross-peaks arising from the sheets, combined with diagonally elongated resonances from additional amide transitions, lead to a characteristic “Z”-shaped pattern for the amide I region in the 2D IR spectrum. We discuss in detail how the number of strands in the sheet, the local configurational disorder in the sheet, the delocalization of the vibrational excitation, and the angle between transition dipole moments affect the position, splitting, amplitude, and line shape of the cross-peaks and diagonal peaks.

    Supersymmetric contributions to Bˉsϕπ0\bar{B}_s \to \phi \pi^0 and Bˉsϕρ0\bar{B}_s \to \phi \rho^0 decays in SCET

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    We study the decay modes Bˉsϕπ0\bar{B}_s\to \phi \pi^0 and Bˉsϕρ0\bar{B}_s\to \phi \rho^0 using Soft Collinear Effective Theory. Within Standard Model and including the error due to the SU(3) breaking effect in the SCET parameters we find that BR Bˉsϕπ0=712+1+2×108\bar{B}_s\to \phi \pi^0 =7_{-1-2}^{+1+2}\times 10^{-8} and BR Bˉsϕπ0=914+1+3×108\bar{B}_s\to \phi \pi^0=9_{-1-4}^{+1+3}\times 10^{-8} corresponding to solution 1 and solution 2 of the SCET parameters respectively.For the decay mode Bˉsϕρ0\bar{B}_s\to \phi \rho^0, we find that BR Bˉsϕρ0=20.2112+1+9×108\bar{B}_s\to \phi \rho^0 = 20.2^{+1+9}_{-1-12}\times 10^{-8} and BR Bˉsϕρ0=34.01.522+1.5+15×108 \bar{B}_s\to \phi \rho^0 = 34.0^{+1.5 + 15}_{-1.5-22}\times 10^{-8} corresponding to solution 1 and solution 2 of the SCET parameters respectively. We extend our study to include supersymmetric models with non-universal A-terms where the dominant contributions arise from diagrams mediated by gluino and chargino exchanges. We show that gluino contributions can not lead to an enhancement of the branching ratios of Bˉsϕπ0\bar{B}_s\to \phi \pi^0 and Bˉsϕρ0\bar{B}_s\to \phi \rho^0. In addition, we show that SUSY contributions mediated by chargino exchange can enhance the branching ratio of Bˉsϕπ0\bar{B}_s\to \phi \pi^0 by about 14% with respect to the SM prediction. For the branching ratio of Bˉsϕρ0\bar{B}_s\to \phi \rho^0, we find that SUSY contributions can enhance its value by about 1% with respect to the SM prediction.Comment: 25 pages,5 figures, version accepted for publicatio
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