Subtleties in CPT-Transformation for Majorana fermions

We point out the relevance of the so-called Majorana creation phase in the s-channel matrix elements in connection with the CPT-transformation of the latter.Comment: 6 pages, to appear in Phys. Rev.

CP-odd Neutral Higgs Effects in Top -- anti-Top Production

We study $CP$ violation in the process $e^+e^- \to t\bar{t} \nu\bar{\nu}$ at an $e^+e^-$-TeV collider. As the source of $CP$ violation we assume a two-Higgs doublet model with an explicitly $CP$-noninvariant Higgs potential. Sizeable $CP$-odd observables originating from the subprocess reaction, $W^+W^- \to t\bar{t}$, may arise as a result of finite width effects of the neutral Higgs particles. $CPT$ constraints due to final (initial) state interactions are also taken into account. Numerical estimates of the $CP$ asymmetry are given.Comment: 28 pages(2 Figs not included), LaTeX, MZ-TH/92-5

Lateral critical Casimir force in 2D Ising strip with inhomogeneous walls

We analyze the lateral critical Casimir force acting between two planar, chemically inhomogeneous walls confining an infinite 2D Ising strip of width $M$. The inhomogeneity of each of the walls has size $N_1$; they are shifted by the distance $L$ along the strip. Using the exact diagonalization of the transfer matrix, we calculate the lateral critical Casimir force and discuss its properties, in particular its scaling close to the 2D bulk critical point, as a function of temperature, surface magnetic field, and the geometric parameters $M$, $N_1$, $L$. We determine the magnetization profiles which display the formation of the bridge joining the inhomogeneities on the walls and establish the relation between the characteristic properties of the lateral Casimir force and magnetization morphologies. We check numerically that breaking of the bridge is related to the inflection point of the lateral force.Comment: 5 pages, 6 figure

Lateral critical Casimir force in two-dimensional inhomogeneous Ising strip. Exact results

We consider two-dimensional Ising strip bounded by two planar, inhomogeneous walls. The inhomogeneity of each wall is modeled by a magnetic field acting on surface spins. It is equal to $+h_1$ except for a group of $N_1$ sites where it is equal to $-h_1$. The inhomogeneities of the upper and lower wall are shifted with respect to each other by a lateral distance $L$. Using exact diagonalization of the transfer matrix, we study both the lateral and normal critical Casimir forces as well as magnetization profiles for a wide range of temperatures and system parameters. The lateral critical Casimir force tends to reduce the shift between the inhomogeneities, and the excess normal force is attractive. Upon increasing the shift $L$ we observe, depending on the temperature, three different scenarios of breaking of the capillary bridge of negative magnetization connecting the inhomogeneities of the walls across the strip. As long as there exists a capillary bridge in the system, the magnitude of the excess total critical Casimir force is almost constant, with its direction depending on $L$. By investigating the bridge morphologies we have found a relation between the point at which the bridge breaks and the inflection point of the force. We provide a simple argument that some of the properties reported here should also hold for a whole range of different models of the strip with the same type of inhomogeneity