Fast and Flexible Vertex Fit

摘要

A least squares method is proposed to fit the geometrical parameters of a set of curved tracks assumed to originate in a common vertex: the parameters measured independently for each track are first extrapolated with their weight matrix to a point close to the expected vertex position; then a local parabolic parametrization of the trajectories is used in a fast fitting procedure, where all parameters (vertex coordinates and track parameters) are modified at each iteration: the global amount of computation is roughly proportional to the number of tracks. Moreover this formalism is well suited to add a track to an existing vertex, or to remove a track from it. (ERA citation 11:048609)