Monopoles, instantons and chiral condensate in lattice QCD

We analyze the interplay of topological objects in four-dimensional QCD at finite temperature on the lattice. The distributions of color magnetic monopoles in the maximum abelian gauge are computed around instantons. Studies are performed in both pure and full QCD and in both the confinement and deconfinement phase. We find an enhanced probability for monopoles inside the core of an instanton on gauge field average. This is independent of the topological charge definition used. For specific gauge field configurations we visualize the situation graphically. Moreover the correlation of monopole loops and instantons with the chiral condensate is investigated. Strong evidence is found that clusters of the quark condensate and topological objects coexist locally on individual configurations.     

Quark chiral condensate from the overlap quark propagator

From the overlap lattice quark propagator calculated in the Landau gauge,we determine the quark chiral condensate by fitting operator product expansion formulas to the lattice data.The quark propagators are computed on domain wall fermion configurations generated by the RBC-UKQCD Collaborations with N_f = 2 + 1flavors.Three ensembles with different light sea quark masses are used at one lattice spacing 1/a = 1.75(4) Ge V.We obtain ψψ (2 GeV)MS =(-304(15)(20) MeV)~3in the SU(2) chiral limit.     

Self-consistent crystalline condensate in chiral Gross-Neveu and Bogoliubov-de Gennes systems

We derive a new exact self-consistent crystalline condensate in the (1+1)-dimensional chiral Gross-Neveu model. This also yields a new exact crystalline solution for the one dimensional Bogoliubov-de Gennes equations and the Eilenberger equation of semiclassical superconductivity. We show that the functional gap equation can be reduced to a solvable nonlinear equation and discuss implications for the temperature-chemical potential phase diagram.     

Non-equilibrium plasma: Theory and experiment

Transport properties of highly excited semiconductors are investigated. The model under consideration is an interacting electron-hole-acoustic phonon system far from equilibrium, described by parametrized single-particle distribution functions. Attention is focused on ambipolar transport of the electronic subsystem including diffusion, thermodiffusion, and drift. Modifications due to many-body effects are discussed. The theoretical scheme is used to interpret experimental data from various optical measurements.     

Production of classical pion field and/or disoriented chiral condensate

We discuss the possibility of production of a classical pion field in high energy nuclei-nuclei collisions. We show that the occupation number for the produced pions can be large as required for the case of a classical field. By examination of the cooling we conclude that in the “quench” scenario it is unlikely to produce a large domain of DCC. The size of domain can be essentially larger due to the temperature dependence of the parameters of the effective Lagrangian. However even in this case the decay of the DCC leads to the production of no more than several tenths of pions which are not easy to distinguish from the “normal” pions.     

External non-white noise: Theory and experiment

We consider a system under the influence of an external gaussian noise with a flat spectrum and finite cut-off frequency. The stationery properties of the system are studied as a function of the correlation time of the noise. Theoretical predictions based on an expansion in powers of the correlation time are corroborated by experimental measurements on an electric circuit with a digital noise generator. The two main qualitative properties experimentally observed which can not be explained in a white noise limit theory are: (i) appearance of relative extrema of the stationery distribution for high noise intensity when the correlation time is not too small; (ii) dependence on the noise characteristics of the position of the maximum of the stationary distribution for low noise intensity.     

Decay of a large-amplitude bubble of a disoriented chiral condensate

The time evolution of a large-amplitude bubble of a disoriented chiral condensate (DCC) is studied. It is found that the evolution of such objects may have a relatively long predecay stage. A simple explanation of such a delay is proposed for the case of the DCC bubble decay. This delay is associated with the existence of approximate multisoliton solutions to the relevant radial sine-Gordon equation in (3+1) dimensions at a large bubble radius.     

Breaking of chiral symmetry and spontaneous rotation in a spinor Bose-Einstein condensate

We show that a spin-1 Bose-Einstein condensate with ferromagnetic interactions spontaneously generates a topological spin texture, in which the m = +/- 1 components of the magnetic sublevels form vortices with opposite circulations. This phenomenon originates from an interplay between ferromagnetic interactions and spin conservation.