Isospinning Skyrmions

In the Skyrme model atomic nuclei are modelled as quantized soliton solutions in a nonlinear field theory of pions. The mass number is given by the conserved topological charge B of the solitons. Conventionally, Skyrmions are semiclassically quantized within the rigid body approach. In this approach Skyrmions are effectively treated as rigid rotors in space and isospace that is it is assumed that Skyrmions do not deform at all when they spin and isospin. This approximation resulted in qualitative and encouraging quantitative agreement with experimental nuclear physics data. In this talk, we point out that the theoretical agreement could be further improved by allowing classical Skyrmion solutions to deform as they spin and isospin. As a first step towards a better understanding of how nuclei can be approximated by classically spinning and isospinning soliton solutions, we study how classical Skyrmion solutions of topological charges B=1?4,8 deform when classical isospin is added

The volume of a soliton

There exists, in general, no unique definition of the size (volume, area, etc., depending on dimension) of a soliton. Here we demonstrate that the geometric volume (area etc.) of a soliton is singled out in the sense that it exactly coincides with the thermodynamical or continuum-mechanical volume. In addition, this volume may be defined uniquely for rather arbitrary solitons in arbitrary dimensions

Roper resonances and quasi-normal modes of Skyrmions

Radial vibrations of charge one hedgehog Skyrmions in the full Skyrme model are analysed. We investigate how the properties of the lowest resonance modes (quasi normal modes) - their frequencies and widths - depend on the form of the potential (value of the pion mass as well as the addition of further potentials) and on the inclusion of the sextic term. Then we consider the inverse problem, where certain values for the frequencies and widths are imposed, and the field theoretic Skyrme model potential giving rise to them is reconstructed. This latter method allows to reproduce the physical Roper resonances, as well as further physical properties of nucleons, with high precision.Comment: LaTex, 24 pages, 18 figure

Radial vibrations of BPS skyrmions

We study radial vibrations of spherically symmetric skyrmions in the BPS Skyrme model. Concretely, we numerically solve the linearised field equations for small fluctuations in a skyrmion background, both for linearly stable oscillations and for (unstable) resonances. This is complemented by numerical solutions of the full nonlinear system, which confirm all the results of the linear analysis. In all cases, the resulting fundamental excitation provides a rather accurate value for the Roper resonance, supporting the hypothesis that the BPS Skyrme model already gives a reasonable approximate description of this resonance. Further, for many potentials additional higher resonances appear, again in agreement with known experimental results.Comment: Latex, 41 pages, 22 pdf figures; v2: minor change

Tunneling decay of false domain walls: the silence of the lambs

We study the decay of "false” domain walls, which are metastable states of the quantum theory where the true vacuum is trapped inside the wall, with the false vacuum outside. We consider a theory with two scalar fields, a shepherd field and a field of sheep. The shepherd field serves to herd the solitons of the sheep field so that they are nicely bunched together. However, quantum tunnelling of the shepherd field releases the sheep to spread out uncontrollably. We show how to calculate the tunnelling amplitude for such a disintegration

Comparison of Wind Speed, Soil Moisture, and Cloud Cover to Relative Humidity to Verify Dew Formation

Satellites such as SMOS are important tools used in many different scientific fields. These satellite readings can have errors due to any number of reasons. Dew can cause a scattering or absorption effect from the microwave emissions which in turn causes errors in satellite data being relayed to scientists and a correction is needed in order to get accurate information. Dew formation can be estimated using relative humidity, but a clear understanding of conditions needed to form dew is desired. Light wind speeds are hypothesized to be needed to induce dew formation in order to have horizontal moisture advection without turbulent mixing. Clear skies overnight are hypothesized to be needed in order to have radiative cooling and high soil moisture is hypothesized to induce dew rise. In this study we will focus on wind speed, cloud cover, and soil moisture over Hardin County, Iowa, and how they can relate to dew formation. Here it was shown that wind speed and cloud cover is not a conclusive way to predict dew formation and soil moisture is the best variable to indicate dew. Therefore, dew rise is the most likely cause of dew formation

Skyrme models and nuclear matter equation of state

We investigate the role of pressure in a class of generalised Skyrme models. We introduce pressure as the trace of the spatial part of the energy-momentum tensor and show that it obeys the usual thermodynamical relation. Then, we compute analytically the mean-field equation of state in the high and medium pressure regimes by applying topological bounds on compact domains. The equation of state is further investigated numerically for the charge one skyrmions. We identify which term in a generalised Skyrme model is responsible for which part in the equation of state. Further, we compare our findings with the corresponding results in the Walecka model