We consider development of sand ripples in shallow water flows which do not reach an equilibrium height but have a time-varying ripple height that slowly reaches a maximum value and then is quickly destroyed by the fluid. A simple scenario to explain the time periodic behavior of the sand ripples...
We introduce a relativistic model for pion-nucleon scattering which includes an elementary
delta dressed by its decay. Crossing-symmetric single-particle exchange
is augmented by parametrized multiple-scattering interactions, with covariant sideways
form factors in both 3- and 4-field vertices. Causality is enforced by dispersion
relations. Unitary fits to observed on-shell amplitudes are...
We develop a technique to express the nucleon pole strength and bare mass in terms of renormalized quantities. Starting from a general unrenormalized self energy we determine the bare mass and the pole strength. For determining the pion content of the nucleon we discuss the leading renormalization loop. We relate...
A new method for evaluating the Lyapunov exponent for a Hamiltonian system
involves a spatial evaluation, rather than a numerical time integration. The
introduction of a novel vector field to the phase space allows the Lyapunov exponent
to be expressed in a form that does not involve time. The Lyapunov...
We used recent phenomenological form factors to calculate the effect of on-shell
two-pion exchange in nucleon-nucleon scattering below the two-pion production
threshold. As expected, the contributions of partial wave amplitudes are all negligible.
We also noticed that the relativistic spin-operator decomposition of the
scattering amplitude is not unique at certain...
We exhibit long-lived resonances in scattering from two-dimensional soft cage potentials comprised of three and four Gaussian peaks. Specific low-energy resonances with very narrow width are shown to correspond to classical multiple-reflection events. These states have much larger probability densities inside the cage than outside and mimic bound states in...