Perturbation Theory of Coulomb Gauge Yang-Mills Theory Within the First Order Formalism

Perturbative Coulomb gauge Yang-Mills theory within the first order formalism is considered. Using a differential equation technique and dimensional regularization, analytic results for both the ultraviolet divergent and finite parts of the two-point functions at one-loop order are derived. It is shown how the non-ultraviolet divergent parts of the results are finite at spacelike momenta with kinematical singularities on the light-cone and subsequent branch cuts extending into the timelike region.Comment: 23 pages, 6 figure

Quantum phase space picture of Bose-Einstein Condensates in a double well: Proposals for creating macroscopic quantum superposition states and a study of quantum chaos

We present a quantum phase space model of Bose-Einstein condensate (BEC) in a double well potential. In a two-mode Fock-state analysis we examine the eigenvectors and eigenvalues and find that the energy correlation diagram indicates a transition from a delocalized to a fragmented regime. Phase space information is extracted from the stationary quantum states using the Husimi distribution function. It is shown that the quantum states are localized on the known classical phase space orbits of a nonrigid physical pendulum, and thus the novel phase space characteristics of a nonrigid physical pendulum such as the $\pi$ motions are seen to be a property of the exact quantum states. Low lying states are harmonic oscillator like libration states while the higher lying states are Schr\"odinger cat-like superpositions of two pendulum rotor states. To study the dynamics in phase space, a comparison is made between a displaced quantum wavepacket and the trajectories of a swarm of points in classical phase space. For a driven double well, it is shown that the classical chaotic dynamics is manifest in the dynamics of the quantum states pictured using the Husimi distribution. Phase space analogy also suggests that a $\pi$ phase displaced wavepacket put on the unstable fixed point on a separatrix will bifurcate to create a superposition of two pendulum rotor states - a Schr\"odinger cat state (number entangled state) for BEC. It is shown that the choice of initial barrier height and ramping, following a $\pi$ phase imprinting on the condensate, can be used to generate controlled entangled number states with tunable extremity and sharpness.Comment: revised version, 13 pages, 13 figure

Generating ring currents, solitons, and svortices by stirring a Bose-Einstein condensate in a toroidal trap

We propose a simple stirring experiment to generate quantized ring currents and solitary excitations in Bose-Einstein condensates in a toroidal trap geometry. Simulations of the 3D Gross-Pitaevskii equation show that pure ring current states can be generated efficiently by adiabatic manipulation of the condensate, which can be realized on experimental time scales. This is illustrated by simulated generation of a ring current with winding number two. While solitons can be generated in quasi-1D tori, we show the even more robust generation of hybrid, solitonic vortices (svortices) in a regime of wider confinement. Svortices are vortices confined to essentially one-dimensional dynamics, which obey a similar phase-offset--velocity relationship as solitons. Marking the transition between solitons and vortices, svortices are a distinct class of symmetry-breaking stationary and uniformly rotating excited solutions of the 2D and 3D Gross-Pitaevskii equation in a toroidal trapping potential. Svortices should be observable in dilute-gas experiments.Comment: 8 pages, 4 figures; accepted for publication in J. Phys. B (Letters

Self-Consistent Pushing and Cranking Corrections to the Meson Fields of the Chiral Quark-Loop Soliton

We study translational and spin-isospin symmetry restoration for the two-flavor chiral quark-loop soliton. Instead of a static soliton at rest we consider a boosted and rotating hedgehog soliton. Corrected classical meson fields are obtained by minimizing a corrected energy functional which has been derived by semi-classical methods ('variation after projection'). We evaluate corrected meson fields in the region 300 MeV \le M \le 600 MeV of constituent quark masses M and compare them with the uncorrected fields. We study the effect of the corrections on various expectation values of nuclear observables such as the root-mean square radius, the axial-vector coupling constant, magnetic moments and the delta-nucleon mass splitting.Comment: 19 pages, LaTeX, 7 postscript figures included using 'psfig.sty', to appear in Int.J.Mod.Phys.

Formation of fundamental structures in Bose-Einstein Condensates

The meanfield interaction in a Bose condensate provides a nonlinearity which can allow stable structures to exist in the meanfield wavefunction. We discuss a number of examples where condensates, modelled by the one dimensional Gross Pitaevskii equation, can produce gray solitons and we consider in detail the case of two identical condensates colliding in a harmonic trap. Solitons are shown to form from dark interference fringes when the soliton structure, constrained in a defined manner, has lower energy than the interference fringe and an analytic expression is given for this condition.Comment: 7 pages, 3 figures, requires ioplppt.st

Hamiltonian approach to QCD in Coulomb gauge - a survey of recent results

I report on recent results obtained within the Hamiltonian approach to QCD in Coulomb gauge. Furthermore this approach is compared to recent lattice data, which were obtained by an alternative gauge fixing method and which show an improved agreement with the continuum results. By relating the Gribov confinement scenario to the center vortex picture of confinement it is shown that the Coulomb string tension is tied to the spatial string tension. For the quark sector a vacuum wave functional is used which explicitly contains the coupling of the quarks to the transverse gluons and which results in variational equations which are free of ultraviolet divergences. The variational approach is extended to finite temperatures by compactifying a spatial dimension. The effective potential of the Polyakov loop is evaluated from the zero-temperature variational solution. For pure Yang--Mills theory, the deconfinement phase transition is found to be second order for SU(2) and first order for SU(3), in agreement with the lattice results. The corresponding critical temperatures are found to be $275 \, \mathrm{MeV}$ and $280 \, \mathrm{MeV}$, respectively. When quarks are included, the deconfinement transition turns into a cross-over. From the dual and chiral quark condensate one finds pseudo-critical temperatures of $198 \, \mathrm{MeV}$ and $170 \, \mathrm{MeV}$, respectively, for the deconfinement and chiral transition.Comment: Talk given by H. Reinhardt at "5th Winter Workshop on Non-Perturbative Quantum Field Theory", 22-24 March 2017, Sophia-Antipolis, France. arXiv admin note: text overlap with arXiv:1609.09370, arXiv:1510.03286, arXiv:1607.0814

Reentrant phase behaviour for systems with competition between phase separation and self-assembly

In patchy particle systems where there is competition between the self-assembly of finite clusters and liquid-vapour phase separation, reentrant phase behaviour is observed, with the system passing from a monomeric vapour phase to a region of liquid-vapour phase coexistence and then to a vapour phase of clusters as the temperature is decreased at constant density. Here, we present a classical statistical mechanical approach to the determination of the complete phase diagram of such a system. We model the system as a van der Waals fluid, but one where the monomers can assemble into monodisperse clusters that have no attractive interactions with any of the other species. The resulting phase diagrams show a clear region of reentrance. However, for the most physically reasonable parameter values of the model, this behaviour is restricted to a certain range of density, with phase separation still persisting at high densities.Comment: 13 pages, 10 figure

Die isolierte Abduzensparese - eine retrospektive Studie an 165 Patienten

In einer retrospektiven Studie wurden die Krankengeschichten von 165 Patienten mit dem Leitsymptom Abduzensparese ausgewertet. Die Parese fand sich links (52%) häufiger als rechts (38%), in 10% war sie beidseitig. Bei 49 Kranken lag eine vaskuläre Genese vor (29.7%), in 35 Fällen bestand ein Diabetes mellitus. Entzündlich bedingte Abduzensparesen (n = 32, 19.4 %) traten vor allem bei der multiplen Sklerose (n = 11), bei viralen Meningoenzephalitiden (n = 5), bei generalisierten Virusinfekten (n = 5) auf. Selten ist eine Impfung ursächlich (n = 1). Unter den Hirntumoren (n = 18, 10.9%) überwogen Metastasen (n = 7) vor Meningiomen (n = 3) und Glioblastomen (n = 2). Nasopharyngeale Karzinome führten viermal per continuitatem zur Abduzensparese. Aneurysmata (n = 7,4.2 %), die eine Lähmung des 6. Hirnnerven bedingen, sitzen bevorzugt am intrakavernösen Internaabschnitt (n = 4). Bei posttraumatischen Abduzensparesen (n = 5, 3.1 %) sind pathologische neuroradiologische Befunde selten. Bei 48 Patienten (29.1 %) blieb die Diagnose unklar, wobei in dieser Gruppe bevorzugt das Alter zwischen dem 20. und 40. Lebensjahr betroffen war. Die Prognose der Abduzensparese vaskulärer und unklarer Genese ist günstig; sie läßt sich durch den Einsatz nichtsteroidaler Antiphlogistika verbessern

The strategic role of middle managers in the formulation and implementation of digital transformation projects

Middle managers play a crucial role in implementing digital strategy. They directly influence the success or failure of an organization's digital transformation. They are the enablers of digital strategy implementation and company transformation and sometimes can cast a sabotaging shadow side when not involved and engaged in the process. However, there are ways to engage them and divert their sabotaging behavior