6,720 research outputs found
Crossed channel analysis of quark and gluon generalized parton distributions with helicity flip
Quark and gluon helicity flip generalized parton distributions (GPDs) address
the transversity quark and gluon structure of the nucleon. In order to
construct a theoretically consistent parametrization of these hadronic matrix
elements, we work out the set of combinations of those GPDs suitable for the
partial wave (PW) expansion in the cross-channel. This universal
result will help to build up a flexible parametrization of these important
hadronic non-perturbative quantities, using for instance the approaches based
on the conformal PW expansion of GPDs such as the Mellin-Barnes integral or the
dual parametrization techniques.Comment: 34 pages, 1 figure, 4 table
Toward modelization of quark and gluon transversity generalized parton distributions
Quark and gluon helicity flip generalized parton distributions (GPDs) encode
the information on the nucleon structure in the transversity sector. In order
to build a theoretically consistent phenomenological parametrization for these
hadronic matrix element within the framework of the dual parametrization of
GPDs (or with the equivalent approach of the SO(3) partial waves (PW) expansion
with the Mellin-Barnes integral techniques) we establish the set of
combinations of parton helicity flip GPDs suitable for the expansion in the
cross channel SO(3) PWs.Comment: 6 pages, DIS 2014, XXII. International Workshop on Deep-Inelastic
Scattering and Related Subjects, 28 April - 2 May 2014, Warsaw, Polan
Mixed Quantum/Classical Approach for Description of Molecular Collisions in Astrophysical Environments
An efficient and accurate mixed quantum/classical theory approach for computational treatment of inelastic scattering is extended to describe collision of an atom with a general asymmetric-top rotor polyatomic molecule. Quantum mechanics, employed to describe transitions between the internal states of the molecule, and classical mechanics, employed for description of scattering of the atom, are used in a self-consistent manner. Such calculations for rotational excitation of HCOOCH3 in collisions with He produce accurate results at scattering energies above 15 cm–1, although resonances near threshold, below 5 cm–1, cannot be reproduced. Importantly, the method remains computationally affordable at high scattering energies (here up to 1000 cm–1), which enables calculations for larger molecules and at higher collision energies than was possible previously with the standard full-quantum approach. Theoretical prediction of inelastic cross sections for a number of complex organic molecules observed in space becomes feasible using this new computational tool
Path Integral Quantization of the Symplectic Leaves of the SU(2)* Poisson-Lie Group
The Feynman path integral is used to quantize the symplectic leaves of the
Poisson-Lie group SU(2)*. In this way we obtain the unitary representations of
U_q(su(2)). This is achieved by finding explicit Darboux coordinates and then
using a phase space path integral. I discuss the *-structure of SU(2)* and give
a detailed description of its leaves using various parametrizations and also
compare the results with the path integral quantization of spin.Comment: 24 pages, LaTeX, no figures, full postscript available from
http://phyweb.lbl.gov/theorygroup/papers/40890.p
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