59,350 research outputs found
B to tensor meson form factors in the perturbative QCD approach
We calculate the form factors within the framework of the
perturbative QCD approach, where denotes a light tensor meson with
. Due to the similarities between the wave functions of a vector and a
tensor meson, the factorization formulas of form factors can be
obtained from the transition through a replacement rule. As a
consequence, we find that these two sets of form factors have the same signs
and correlated -dependence behaviors. At point, the form
factors are smaller than the ones, in accordance with the experimental
data of radiative B decays. In addition, we use our results for the form
factors to explore semilteptonic decays and the branching
fractions can reach the order .Comment: 13 pages, 3 figures, 6 tables, published versio
Chiral Dynamics and S-wave Contributions in Semileptonic B decays
The flavor-changing neutral current process is beneficial to
testing the standard model and hunting for new physics scenarios. In exclusive
decay modes like , the S-wave effects may not be
negligible and thus have to be reliably estimated. Using the scalar form
factors derived from dispersion relations in two channels and matched to Chiral
Perturbation Theory, we investigate the S-wave contributions in , with the invariant mass lying in the vicinity of the
mass of , and the with .
We find that the S-wave will modify differential decay widths by about 10% in
the process of and about 5% in . A forward-backward asymmetry for the charged kaon in the final state
arises from the interference between the S-wave and P-wave contributions. The
measurement of this asymmetry offers a new way to determine the variation of
the S-wave phase versus the invariant mass.Comment: 26 pages, 10 figure
Probability-dependent gain-scheduled filtering for stochastic systems with missing measurements
Copyright @ 2011 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.This brief addresses the gain-scheduled filtering problem for a class of discrete-time systems with missing measurements, nonlinear disturbances, and external stochastic noise. The missing-measurement phenomenon is assumed to occur in a random way, and the missing probability is time-varying with securable upper and lower bounds that can be measured in real time. The multiplicative noise is a state-dependent scalar Gaussian white-noise sequence with known variance. The addressed gain-scheduled filtering problem is concerned with the design of a filter such that, for the admissible random missing measurements, nonlinear parameters, and external noise disturbances, the error dynamics is exponentially mean-square stable. The desired filter is equipped with time-varying gains based primarily on the time-varying missing probability and is therefore less conservative than the traditional filter with fixed gains. It is shown that the filter parameters can be derived in terms of the measurable probability via the semidefinite program method.This work was supported in part by the Leverhulme Trust of the U.K., the Engineering and Physical Sciences Research Council (EPSRC) of the U.K. under Grant GR/S27658/01, the National Natural Science Foundation of China under Grants 61028008, 61074016 and 60974030, the Shanghai Natural
Science Foundation of China under Grant 10ZR1421200, and the Alexander von Humboldt Foundation of Germany
Detect-and-Avoid: Flight Test 6 Scripted Encounters Data Analysis
The Unmanned Aircraft System (UAS) in the National Airspace System (NAS) project conducted Flight Test 6 (FT6) in 2019. The ultimate goal of this flight test was to produce data to inform RTCA SC-228's Phase II Minimum Operational Performance Standards (MOPS) for Detect and Avoid (DAA) and Low Size, Weight, and Power Sensors. This report documents the analysis of scripted encounters' data. Scripted encounters own were analyzed and categorized based on the outcome of alert, maneuver guidance, and effectiveness of pilots' maneuver in resolving conflicts. Results indicate that UAS pilots' decisions as well as intruder maneuvers are leading factors that contribute to ineffective DAA maneuvers. Results also show that adding buffers to the DAA's suggested minimum turn angle improves effectiveness of the DAA maneuvers
Novel accelerating Einstein vacua and smooth inhomogeneous Riemannian manifolds
A novel class of Einstein vacua is presented, which possess non-vanishing
cosmological constant and accelerating horizon with the topology of
fibration over . After Euclideanization, the solution describes a
conformally distorted fibration over , which is smooth, compact
and inhomogeneous, and can be regarded as analogue of Don Page's gravitational
instanton.Comment: 14 pages. v2: Reference adde
- …