In the most recent year of data-taking with the ATLAS detector at the Large Hadron Collider (LHC), the minimum pT of reconstructed tracks was 500 MeV. This bound was set to reduce the amount of combinatorial problem solving required and to save disk space, which is a challenge in high pileup environments. However, most proton-proton collisions at the LHC will result in a large number of soft particles. While ATLAS does have two frameworks in place for performing low-pT tracking in low pileup runs, for some analyses, the reconstruction of these soft particles in high pileup can provide important information. This talk will explain a method of tracking in high pileup where low-pt tracks are reconstructed in a second tracking pass after default tracking and will elaborate on problems such as seed optimization, hit selection, and offline track selection requirements. Additionally, in order to prevent a large increase in the per-event reconstruction time, tracks are only reconstructed within a “region of interest”, which is defined event-by-event. This method of tracking has been developed and tested by a team searching for photon-induced WW production at the LHC. Other analyses should be able to use this tracking method too; for example, charm tagging can be improved by reconstructing low-pt particles.
|Consider for young scientist forum (Student or postdoc speaker)||Yes|