We acknowledge support by the Deutsche Forschungsgemeinschaft under Project No.
The possible bound-states in this regime correspond to charge-spin separation and pairing. As a consequence of the above, the gauge-fields mediate a confining interaction among dopant holes and S-1/2 magnetic excitations only in the quantum disordered phase. The explicit doping dependence of the spin-gap is determined as a function of the parameters of the original model. Within a large-N expansion, the strength of the gauge fields is found to be determined by the gap in the spin-wave spectrum, which is dynamically generated. that the low-energy limit of the model is equivalent to a U(1) gauge theory, where both the bosonic and fermionic degrees of freedom are coupled minimally to a vector gauge field. By choosing local spin quantization axes for the fermions we show.
GRAW 2 EXTRACT BUNDLE FILES FREE
Finally, alternative geometric approaches are investigated.Ī quantitative description of the transition to a quantum disordered phase in a doped antiferromagnet is obtained for the long-wavelength limit of the spin-fermion model, which is given by the O(3) nonlinear sigma model, a free fermionic part and current-current interactions as obtained by Shraiman and Siggia for the t - J model. Some of these problems have been solved, and for others possible routes to follow have been laid down. The previously proposed theories are thoroughly examined, certain subtleties and problems in them have been discovered and made apparent. This thesis constitutes a further development for obtaining a consistent dynamical theory of the diffeomorphism field. With this motivation, several dynamical theories for the diffeomorphism field have been constructed by mimicking construction of Yang-Mills theory from Kac-Moody algebra. This raises the question of whether the diffeomorphism field exists in higher dimensions, and plays an essential role in gravity. Moreover, the diffeomorphism field can be interpreted as the gravitational analog of a Yang-Mills field. Einstein's gravity is dynamically trivial in two dimensions. This background field is used to be called the diffeomorphism field. Integration of Kirillov form on a coadjoint orbit of Virasoro algebra yields the coupling of a background field to Polyakov's two dimensional quantum gravity. We look at non-covariant particle dynamics, and present a short introduction to dynamics of (neutral) particles hit by a laser pulse of arbitrary shape. We consider variational action principle and find that a consistent extension of Lorentz force to include magnetic spin force is not straightforward. We show that covariant spin precession lacks a unique form and discuss connection to $g-2$ anomaly. We propose a covariant formulation of the magnetic force based on a \lq magnetic\rq\ 4-potential and show how the point particle magnetic moment relates to the Amperian (current loop) and Gilbertian (magnetic monopole) description. We introduce spin as a classical particle property inherent to Poincare\'e symmetry of space-time. We are interested in understanding Lorentz force extension involving point particle magnetic moment (Stern-Gerlach force) and how the spin precession dynamics is modified for consistency.
The covariant motion of a classical point particle with magnetic moment in the presence of (external) electromagnetic fields is revisited.
As long as one only consider a single photon detector, it is verified that, in this context, there is no fundamental difference between quantum-mechanical interference and interference as expressed in terms of classical electro-magnetic waves. It is, however, also argued that after a proper identification of the relevant quantum-mechanical probability amplitudes one can be reach κ S = 0. In order to show this we consider a mono-chromatic source of photons prepared in an arbitrary quantum state and a simple version of the well-established photon detection theory of Glauber which, by construction, obeys all the rules of quantum mechanics. In fact, we argue that a straightforward interpretation of the procedures involved in a physical determination of κ S does not necessarily lead to κ S = 0. Here we argue that a physical realization of such arguments could lead to an erroneous conclusion and contradict the basic rules of quantum mechanics. In terms of a certain parameter κ S, it was argued that a non-zero value could imply a breakdown of the fundamental Born's rule as well as the superposition principle. It has been suggested by Sorkin that a three-slit Young experiment could reveal the validity a fundamental ingredient in the foundations of one of the cornerstones in modern physics namely quantum mechanics.
0 kommentar(er)
