Baby Skyrme Model, Near-BPS Approximations and Supersymmetric Extensions

We study the baby Skyrme model as a theory that interpolates between two distinct BPS systems. For this a near-BPS approximation can be used which, however, involves a small deviation from each of the two BPS limits. We provide analytical explanation and numerical support for the validity of this approximation. We then study the set of all possible supersymmetric extensions of the baby Skyrme model with ${\cal N}=1$ and the particular ones with extended ${\cal N}=2$ supersymmetries and relate this to the above mentioned almost-BPS approximation.Comment: 23 pages, 5 figures, v2: explanations adde

Multibaryons with strangeness, charm and bottom

Static properties of multiskyrmions with baryon numbers up to 8 are calculated, including momenta of inertia and sigma-term. The calculations are based on the recently suggested SU(2) rational map ansaetze. Minimization with the help of SU(3) variational minimization program shows that these configurations become local minima in SU(3) configuration space. The B-number dependence of the so called flavour moment of inertia of multiskyrmions playing an important role in the quantization procedure is close to the linear one. The spectra of baryonic systems with strangeness, charm and bottom are considered within a "rigid oscillator" version of the bound state soliton model. The binding energies estimates are made for the states with largest isospin which can appear as negatively charged nuclear fragments, as well as for states with zero isospin - light fragments of "flavoured" nuclear matter. Our results confirm the previously made observation that baryonic systems with charm or bottom quantum numbers have more chance to be stable with respect to strong interactions than strange baryonic systems.Comment: 13 pages, no figures. Submitted to Eur. Phys.

Mean field dynamics of superfluid-insulator phase transition in a gas of ultra cold atoms

A large scale dynamical simulation of the superfluid to Mott insulator transition in the gas of ultra cold atoms placed in an optical lattice is performed using the time dependent Gutzwiller mean field approach. This approximate treatment allows us to take into account most of the details of the recent experiment [Nature 415, 39 (2002)] where by changing the depth of the lattice potential an adiabatic transition from a superfluid to a Mott insulator state has been reported. Our simulations reveal a significant excitation of the system with a transition to insulator in restricted regions of the trap.Comment: final version, correct Fig.7 (the published version contains wrong fig.7 by mistake