324 research outputs found
From Lattice Gauge Theories to Hydrogen Atoms
We construct canonical transformations to obtain a complete and most
economical realization of the physical Hilbert space of pure
lattice gauge theory in terms of Wigner coupled Hilbert spaces of
hydrogen atoms. One hydrogen atom is assigned to every plaquette of the
lattice. A complete orthonormal description of the Wilson loop basis in is obtained by all possible angular momentum Wigner couplings of hydrogen
atom energy eigenstates describing electric fluxes on the
loops. The SU(2) gauge invariance implies that the total angular momenta of all
hydrogen atoms vanish. The canonical transformations also enable us to rewrite
the Kogut-Susskind Hamiltonian in terms of fundamental Wilson loop operators
and their conjugate electric fields. The resulting loop Hamiltonian has a
global SU(2) invariance and a simple weak coupling ()
continuum limit. The canonical transformations leading to the loop Hamiltonian
are valid for any SU(N). The ideas and techniques can also be extended to
higher dimension.Comment: 8 pages, 5 figures. minor typos corrected, minor changes in abstrac
Quark Wigner Distributions Using Light-Front Wave Functions
The quasi-probabilistic Wigner distributions are the quantum mechanical
analog of the classical phase-space distributions. We investigate quark Wigner
distributions for a quark state dressed with a gluon, which can be thought of
as a simple composite and relativistic spin-1/2 state with a gluonic degree of
freedom. We calculate various polarization configurations, namely unpolarized,
longitudinally polarized and transversely polarized quark and the target state
using light-front wave functions in this model. At leading twist, one can
define 16 quark Wigner distributions, however, we obtain only 8 independent
non-zero Wigner distributions in our model. We compare our results with other
model calculations for the proton.Comment: 21 pages, 5 figures, version published by Phys. Rev.
Three Dimensional Imaging of the Nucleon
We study the Wigner distributions of quarks and gluons in light-front dressed
quark model using the overlap of light front wave functions (LFWFs). We take
the target to be a dressed quark, this is a composite spin state of
quark dressed with a gluon. This state allows us to calculate the quark and
gluon Wigner distributions analytically in terms of LFWFs using Hamiltonian
perturbation theory. We analyze numerically the Wigner distributions of quark
and gluon and report their nature in the contour plots. We use an improved
numerical technique to remove the cutoff dependence of the Fourier transformed
integral over .Comment: 7 pages, 2 figures, Prepared for Proceedings of Light Cone 2017,
18-22 Sept, University of Mumbai, India. To appear in FB
Wigner distributions of quarks for different polarizations
We calculate quark Wigner distributions using the light-front wave functions
in a dressed quark model. In this model, a proton target is replaced by a
simplified spin-1/2 state, namely a quark dressed with a gluon. We calculate
the Wigner distributions for different polarization configuration of quark and
the target state in this model.Comment: 6 pages, 12 figures. Presented by Jai More at Light Cone 2016, 5-8
September 2016, IST, Universidade de Lisboa, Portuga
Wigner Distributions For Gluons
We investigate the gluon Wigner distributions for unpolarized, longitudinally
polarized and transversely polarized target state. Instead of a nucleon, we
take the target state to be a quark dressed with a gluon at one loop and
investigate the gluon Wigner distributions at leading twist. Better numerical
convergence is obtained compared to an earlier study, that removes the
regulator dependence of the results. We present a first calculation of the
Wigner distribution for the transversely polarized target and linearly
polarized gluon. We study the spin densities in momentum and impact parameter
space. We also investigate the quark and gluon helicity and orbital angular
momentum distributions at small-.Comment: 27 pages, 10 figures, two figures added, replaced with the revised
version published in EPJ
Optimization of Resistance Spot Welding Process Parameters using MOORA Approach
Optimization of resistance spot welding (RSW) process parameters was carried out to obtain optimal parametric combination to yield favourable weld nugget diameter, heat affected zone (HAZ) and breaking load in AISI 316 L austenitic stainless steel plates. Taguchi’s L16 orthogonal array (OA) design and signal- to- noise ratio (S/N ratio) have been used in this study. Weld nugget diameter, heat affected zone (HAZ) and breaking load are selected as objective functions. In this case the multi objective optimization on the basis of ratio analysis (MOORA) is applied to solve this multi objective, problem. MOORA in combination with standard deviation (SDV) was used for optimization process. Standard deviation (SDV) was used to determine the weights that were used for normalizing the responses obtained from the experimental results. It was found that welding current of 14 kA, welding time 14 cycle, electrode force 200Kgf and holding time 10 cycle produced the weldment with the best mechanical properties. This method can be used successfully in other welding applications
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