Heterotic string models in which the space-time gauge symmetry is realized as a level k > 2 Kac-Moody algebra on the string world-sheet offer phenomenological features not present for the level k = 1 case (which includes all heterotic string models seriously considered to date). In particular, string models with N=l space-time supersymmetry and/or chiral matter fields can contain massless scala...

We introduce two maximal non-abelian gauge xing conditions on the space of gauge orbits M for gauge theories over spaces with dimensions d 3. The gauge xings are complete in the sense that describe an open dense set M 0 of the space of gauge orbits M and select one and only one gauge eld per gauge orbit in M 0. There are not Gribov copies or ambiguities in these gauges. M 0 is a contractible ma...

We introduce two maximal non-abelian gauge xing conditions on the space of gauge orbits M for gauge theories over spaces with dimensions d 3. The gauge xings are complete in the sense that describe an open dense set M 0 of the space of gauge orbits M and select one and only one gauge eld per gauge orbit in M 0. There are not Gribov copies or ambiguities in these gauges. M 0 is a contractible ma...

We introduce two maximal non-abelian gauge fixing conditions on the space of gauge orbits M for gauge theories over spaces with dimensions d ≤ 3. The gauge fixings are complete in the sense that describe an open dense set M0 of the space of gauge orbits M and select one and only one gauge field per gauge orbit in M0. There are not Gribov copies or ambiguities in these gauges. M0 is a contractib...

A gauge-invariant field is found which describes physical configurations, i.e. gauge orbits, of non-Abelian gauge theories. This is accomplished with non-Abelian generalizations of the Poincaré-Hodge decomposition formula for one-forms. In a particular sense, the new field is dual to the gauge field. Using this field as a coordinate, the metric and Riemann curvature are discussed for Yang-Mills...

We study the relationship between general dynamical Poisson groupoids and Lie quasi-bialgebras. For a class of Lie quasi-bialgebras G naturally compatible with a reductive decomposition , we extend the description of the moduli space of classical dynamical r-matrices of Etingof and Schiffmann. We construct, in each gauge orbit, an explicit analytic representative l can. We translate the notion ...

We consider an SU(2)L × SU(2)R × U(1)B−L × SU(3) L H gauge model with natural flavour conservation in the Higgs sector, in which CP-violation occurs due to the horizontal interactions only. We calculate the CP-violating observables ǫ and ǫ′ of the neutral kaon sector and dn, the electric dipole moment of the neutron. The regions of the parameter space which yield a value of ǫ that is in agreeme...

We investigate the properties of the QCD string in the Euclidean SU(N) pure gauge theory when the space-time dimensions transverse to it are periodic. We propose a generalisation of the Lüscher-Weisz effective string action for the flux-tube energy levels at finite L⊥. As the size of one transverse dimension is varied, we predict a Kosterlitz-Thouless transition of the worldsheet field theory a...

The a-model describing the propagation of the heterotic string in a CalabiYau background is written down in the Green-Schwarz formulation. This model has manifest N=l space-time supersymmetry, however only the SO(2) subgroup of the four dimensional Lorentz group is realized linearly. The criteria for the existence of the full SO(3,l) L orentz symmetry in this model are studied. These requiremen...

We discuss a general method of revealing both space-space and space-time noncommuting structures in various models in particle mechanics exhibiting reparametrisation symmetry. Starting from the commuting algebra in the conventional gauge, it is possible to obtain a noncommuting algebra in a nonstandard gauge. The change of variables relating the algebra in the two gauges is systematically deriv...