6 research outputs found
Spin-1 Particles with Light-Front Approach
For the vector sector, i.e, mesons with spin-1, the electromagnetic form
factors and anothers observables are calculated with the light-front approach.
However, the light-front quantum field theory have some problems, for example,
the rotational symmetry breaking. We solve that problem added the zero modes
contribuition to the matrix elements of the electromagnetic current, besides
the valence contribuition. We found that among the four independent matrix
elements of the plus component in the light-front helicity basis only the one carries zero mode contributions.Comment: 5 pages. 3 Figures, use latex and EPJ styl
Vortex generation in stirred binary Bose-Einstein condensates
The dynamical vortex production, with a trap-confining time-dependent stirred
potential, is studied by using mass-imbalanced cold-atom coupled Bose-Einstein
condensates (BEC). The vortex formation is explored by considering that both
coupled species are confined by a pancake-like harmonic trap, slightly modified
elliptically by a time-dependent periodic potential, with the characteristic
frequency enough larger than the transversal trap frequency. The approach is
applied to the experimentally accessible binary mixtures Rb-Cs
and Rb-Rb, which allow us to verify the effect of mass
differences in the dynamics. For both species, the time evolutions of the
respective energy contributions, together with associated velocities, are
studied in order to distinguish turbulent from non-turbulent flows. By using
the angular momentum and moment of inertia mean values, effective classical
rotation frequencies are suggested, which are further considered within
simulations in the rotating frame without the stirring potential. Spectral
analysis is also provided for both species, with the main focus being the
incompressible kinetic energies. In the transient turbulent regime, before
stable vortex patterns are produced, the characteristic Kolmogorov
behavior is clearly identified for both species at intermediate momenta
above the inverse Thomas-Fermi radial positions, further modified by the
universal scaling at momenta higher than the inverse of the respective
healing lengths.
Emerging from the mass-imbalanced comparison, relevant is to observe that, as
larger is the mass difference, much faster is the dynamical production of
stable vortices.Comment: 17 pages, 16 figure