نتایج جستجو برای: angular distribution
تعداد نتایج: 674646 فیلتر نتایج به سال:
Exclusive electroproduction of π+π− pairs off hydrogen and deuterium targets has been studied with the HERMES experiment. The angular distribution of the π+ in the π+π− rest system has been studied in the invariant mass range 0.3 < mππ < 1.5 GeV. Theoretical models derived in the framework of the Generalized Parton Distributions show that this angular distribution receives only contributions fr...
We have measured the angular distribution of carbon K-Auger electrons from fixed in space, core-ionized, CO molecules in coincidence with the kinetic energy release of the C+ and O+ fragments. We find a very narrow ejection of Auger electrons in the direction of the oxygen and an oscillatory diffraction pattern. Even for similar electron energies, the angular distribution strongly depends on th...
We examine angular distributions of leptons arising from the decay of J/ψ in inclusive hadroproduction. Taking into account feed-down contributions from χ1,2, a flat distribution emerges without fine tuning parameters. Changes in the ratio of direct to total J/ψ cross sections would change this distribution significantly. Such angular distributions are, therefore, confirmatory tests of the J/ψ ...
This paper provides a regression model in which both covariates and responses are angular variables. The regression curve is expressed as a form of the Möbius circle transformation. The angular error is assumed to follow a wrapped Cauchy or, equivalently, circular Cauchy distribution. A bivariate circular distribution is proposed to model our circular regression. Some properties of the regressi...
The HEGRA system of imaging atmospheric Cherenkov telescopes provides for specially selected classes of events an angular resolution of better than 3'. By comparing the measured angular distribution of TeV gamma rays from the Crab Nebula with the distribution expected on the basis of Monte Carlo simulations, and with measurements of gamma rays from the point source Mrk 501, we conclude that the...
We calculate the nuclear enhancement in the angular distribution of Drell-Yan pairs produced in proton–nucleus reactions. Nuclear effects are encoded in universal twist-4 parton correlation functions. We find that the Lam-Tung relation for the angular coefficients of the lepton-pair distribution holds for the double-hard, but not for the soft-hard contribution. We also predict that nuclear enha...
The determination of quark angular momentum requires the knowledge of the generalized parton distribution E in the forward limit. We assume a connection between this function and the Sivers transverse-momentum distribution, based on model calculations and theoretical considerations. Using this assumption, we show that it is possible to fit nucleon magnetic moments and semi-inclusive single-spin...
Here the hollow vortex Gaussian beam is described by the exact solution of the Maxwell equations. By means of the method of the vectorial angular spectrum, analytical expressions of the electromagnetic fields of a hollow vortex Gaussian beam propagating in free space are derived. By using the electromagnetic fields of a hollow vortex Gaussian beam beyond the paraxial approximation, one can calc...
If Gamma-Ray Bursts (GRBs) are cosmologically distributed standard candles and are associated with the luminous galaxies, then the observed angular distribution of all GRBs is altered due to weak gravitational lensing of bursts by density inhomogeneities. The amplitude of the effect is generally small. For example, if the current catalogs extend to zmax ∼ 1 and we live in a flat Ω = 1 Universe,...
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