Application of vertex and mass constraints in track-based alignment

TL;DR

This paper introduces an alignment method for tracking detectors that uses decay vertex and mass constraints to correct distortions, improving vertex and momentum resolution in particle physics experiments.

Contribution

The paper presents a novel alignment procedure that incorporates vertex and mass constraints to mitigate detector distortions, demonstrated with D^0 decay data at LHCb.

Findings

Reduced curvature bias in the LHCb spectrometer

Improved vertex and momentum resolution

Effective correction of global detector distortions

Abstract

The software alignment of planar tracking detectors using samples of charged particle trajectories may lead to global detector distortions that affect vertex and momentum resolution. We present an alignment procedure that constrains such distortions by making use of samples of decay vertices reconstructed from two or more trajectories and putting constraints on their invariant mass. We illustrate the method by using a sample of invariant-mass constrained vertices from D^0 --> K^- pi^+ decays to remove a curvature bias in the LHCb spectrometer.