3,695,316 research outputs found

    Physical renormalization condition for the quark-mixing matrix

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    We investigate the renormalization of the quark-mixing matrix in the Electroweak Standard Model. We show that the corresponding counterterms must be gauge independent as a consequence of extended BRS invariance. Using rigid SU(2)_L symmetry, we proof that the ultraviolet-divergent parts of the invariant counterterms are related to the field renormalization constants of the quark fields. We point out that for a general class of renormalization schemes rigid SU(2)_L symmetry cannot be preserved in its classical form, but is renormalized by finite counterterms. Finally, we discuss a genuine physical renormalization condition for the quark-mixing matrix that is gauge independent and does not destroy the symmetry between quark generations.Comment: 20 pages, LaTeX, minor changes, references adde

    Effects of a Tapering Period on Physical Condition in Soccer Players

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    The aim of this research was to analyze the effects of a 2-week step tapering period on lower-limb muscle power, change of direction (COD) and acceleration capacities, and on the stress-recovery state in an amateur soccer team. Twenty-two male players were included in the study. After a 6-week progressive training, the sample was divided into experimental group (EG) (n = 11), which did a 2-week period of taper in which training volume was 50% reduced (intensity was kept high) and control group (CG) (n = 11), which kept on with the training. Muscle power (countermovement jump test), acceleration (10-m sprint test), COD (Illinois test), and stress and recovery perceptions (RESTQ questionnaire) were evaluated before training, at the end of it (pretapering, PRE-TP) and after the tapering period (posttapering, POST-TP). After the taper, the EG in comparison with the CG showed significantly improved power (1,029.71 ± 108.51 W·kg−1 vs. 1,084.21 ± 110.87 W·kg−1; p ≤ 0.01), acceleration (1.72 ± 0.09 seconds vs. 1.67 ± 0.07 seconds; p ≤ 0.05), and lower stress levels (1.9 ± 0.5 vs. 1.6 ± 0.5; p ≤ 0.01) (PRE-TP vs. POST-TP, respectively). Change of direction did not show significant changes. In conclusion, a 2-week step tapering program was found to be an effective periodization strategy to increase muscle power and acceleration, and to reduce stress perception in soccer amateur players

    Invertible condition of quantum Fisher information matrix for a mixed qubit

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    Estimating multiparamter simultaneously as precise as possible is an important goal of quantum metrolo- gy. As a first step to this end, here we give a condition determining whether two arbitrary parameters can be estimated simultaneously for a qubit in the mixed state. An application of this condition is shown.Comment: The European Physical Journal D 201

    On the Tuning Condition of Split Supersymmetry

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    Split Supersymmetry does not attempt to solve the hierarchy problem, but it assumes a tuning condition for the electroweak scale. We clarify the meaning of this condition and show how it is related to the underlying parameters. Simple assumptions on the structure of the soft terms lead to predictions on tan beta and on the physical Higgs mass.Comment: 9 pages, 6 figures, latex2

    Galerkin Methods for Boltzmann-Poisson transport with reflection conditions on rough boundaries

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    We consider in this paper the mathematical and numerical modelling of reflective boundary conditions (BC) associated to Boltzmann - Poisson systems, including diffusive reflection in addition to specularity, in the context of electron transport in semiconductor device modelling at nano scales, and their implementation in Discontinuous Galerkin (DG) schemes. We study these BC on the physical boundaries of the device and develop a numerical approximation to model an insulating boundary condition, or equivalently, a pointwise zero flux mathematical condition for the electron transport equation. Such condition balances the incident and reflective momentum flux at the microscopic level, pointwise at the boundary, in the case of a more general mixed reflection with momentum dependant specularity probability p(k)p(\vec{k}). We compare the computational prediction of physical observables given by the numerical implementation of these different reflection conditions in our DG scheme for BP models, and observe that the diffusive condition influences the kinetic moments over the whole domain in position space.Comment: Paper accepted for publication in Journal of Computational Physics. -Conclusions section expanded -Title changed with respect to previous preprint version -New subsections related to simulations of 2D double gated MOSFET and comparison of bulk silicon with collisionless plasma under reflective and periodic boundary condition
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