نتایج جستجو برای: helicity

تعداد نتایج: 4632  

2008
A. R. Yeates

The hemispheric pattern of solar filaments is considered using newlydeveloped simulations of the real photospheric and 3D coronal magnetic fields over a 6-month period, on a global scale. The magnetic field direction in the simulation is compared directly with the chirality of observed filaments, at their observed locations. In our model the coronal field evolves through a continuous sequence o...

1998
Charles A. Nelson Andrew M. Cohen

The standard model(SM) predicts only a gV−A coupling in t → W+b decay. However, if additional Lorentz structures exist, they can manifest themselves in high energy processes such as this via non-SM values of the helicity parameters describing t → W+b. Plots and tables of the values of these helicity parameters are obtained for various coupling strengths. Three phase-type ambiguities are uncover...

2002
Donald M. LEVINE

The kinematical constraints of helicity amplitudes are studied using the general ideas of Jackson and Hite. The helicity amplitudes are expressed in terms of a Taylor ser ies expansion from which all constraints at threshold and pseudothreshold can be tr ivial ly found. The simplicity of this approach is i l lustrated by deriving all of the constraints for 7rp --* N~ and ~rp --* AN.

2002
E. GUADAGNINI

The helicity modification of light polarization which is induced by the gravitational deflection from a classical heavy rotating body, like a star or a planet, is considered. The expression of the helicity asymmetry is derived; this asymmetry signals the gravitationally induced spin transfer from the rotating body to the scattered photons. E-Mail: [email protected]

2013
Lance J. Dixon

I provide a basic introduction to modern helicity amplitude methods, including color organization, the spinor helicity formalism, and factorization properties. I also describe the BCFW (on-shell) recursion relation at tree level, and explain how similar ideas — unitarity and on-shell methods — work at the loop level. These notes are based on lectures delivered at the 2012 CERN Summer School and...

2005
Ruth Britto Bo Feng Radu Roiban Marcus Spradlin Anastasia Volovich

Recently a new recursion relation for tree-level gluon amplitudes in gauge theory has been discovered. We solve this recursion to obtain explicit formulas for the closed set of amplitudes with arbitrarily many positive and negative helicity gluons in a split helicity configuration. The solution admits a simple diagrammatic expansion in terms of ‘zigzag’ diagrams. We comment on generalizations o...

2005
M. Göckeler Ph. Hägler R. Horsley D. Pleiter P. E. L. Rakow A. Schäfer G. Schierholz J. M. Zanotti

This talk presents results from the QCDSF-UKQCD collaboration for moments of leading twist generalized parton distributions in two-flavor lattice QCD based on O(a) improved Wilson Fermions. We study helicity independent and helicity flip GPDs with a focus on densities of quarks in the transverse plane.

1997
A. Widom

That a Majorana neutrino theory is different from a Dirac neutrino theory (even in the zero mass limit) is proved in two sentences. Fermion Statistics For the reactions (Dirac) e + e − → ν ¯ ν and (Majorana) e + e − → νν wherein the two final particles are presumed to have opposite helicity, in the Dirac case the neutrino and anti-neutrino are different particles so that Ψ Dirac (p 1 , λ 1 ; ¯ ...

2006
Abolfazl Jafari

The amplitudes of purely photonic and photon–2-fermion processes of noncommutative QED (NCQED) are derived for different helicity configurations of photons. The basic ingredient is the NCQED counterpart of Yang-Mills recursion relations by means of Berends and Giele. The explicit solutions of recursion relations for NCQED photonic processes with special helicity configurations are presented.

Journal: :Angewandte Chemie 2017
Rodrigo A Cormanich David O'Hagan Michael Bühl

Hyperconjugative, steric, and electrostatic effects were evaluated as possible sources of the helicity in linear perfluorinated alkanes through analysis of natural bond orbitals and classical electrostatics. Contrary to previous rationalizations, which indicate dominating steric or electrostatic effects, this analysis indicates that hyperconjugative stabilization through σCC →σ*CF interactions ...

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