International Journal of Modern Physics A

In this review I summarize the results obtained by CDF on top physics. After the discovery of the top quark, the efforts were concentrated on obtaining precision measurements of the observables. A description of the algorithms developed and used to isolate top in various samples is given, together with the discussion of background and selection strategies followed. The measurements of top mass and production cross section are discussed in detail and studies related to top decays and kinematics of events are presented.

We study the crossing symmetry of the conformal blocks of the conformal field theory based on the affine Lie superalgebra osp(1|2). Within the framework of a free field realization of the osp(1|2) current algebra, the fusion and braiding matrices of the model are determined. These results are related in a simple way to those corresponding to the su(2) algebra by means of a suitable identification of parameters. In order to obtain the link invariants corresponding to the osp(1|2) conformal field theory, we analyze the corresponding topological Chern–Simons theory. In a first approach we quantize the Chern–Simons theory on the torus and, as a result, we get the action of the Wilson line operators on the supercharacters of the affine osp(1|2). From this result we get a simple expression relating the osp(1|2) polynomials for torus knots and links to those corresponding to the su(2) algebra. Further, this relation is verified for arbitrary knots and links by quantizing the Chern–Simons theory on the punctured two-sphere.

A variational method is used to investigate the dynamics of extended objects. The stationary world volume requires the internal coordinates to propagate as free waves. Stationarity of the action which is the integral of a variable energy density over the world volume leads to the wave equation in a medium, with conductivity given by the gradient of the logarithm of reciprocal energy density, constant density corresponding to free space. The Einstein–Hilbert action for the world curvature gives an equation of motion which, in world space with the Einstein tensor proportional to the metric tensor, reduces to the free wave equation. A similar method applied to the action consisting of the surface area enclosing an incompressible world volume undergoing pure shear again yields the wave equation in a conducting medium. Simultaneous stationarity of the volume can be imposed with a stationary area only in the case of pure shear; stationary Einstein–Hilbert action can also be included and lead to an equation of motion which has a similar interpretation of the wave in the conducting medium. Some Green functions applicable to the medium with constant conductivity are also presented.

In the past two decades, Dyson's formalism of renormalization has been mostly superceded by dimensional regularization, particularly in the treatment of quantum gauge field theories with spontaneous symmetry breaking or those with chiral fermions. In this paper, we shall carry out explicitly Dyson's subtraction program, making it applicable to such field theories. In particular, we show with the example of the Abelian–Higgs theory how to handle amplitudes of chiral fermions. We show that these amplitudes which involve the γ₅ matrix can be calculated in an unambiguous and gauge invariant way. This is done by establishing the subtraction conditions for the propagator of a chiral fermion as well as those for the VVV amplitude, when V denotes the vector meson. The renormalized constants are chosen to satisfy the Ward–Takahashi identities. As a demonstration, we calculate the next-lowest order correction of the anomaly in the Abelian–Higgs model and find that it vanishes.