James Catmore (University of Oslo (NO)) Roger Jones (Lancaster University (GB))
Based on experience gained from run-I of the LHC, the ATLAS vertex reconstruction group has developed a refined primary vertex reconstruction strategy for run-II. With instantaneous luminosity exceeding 10^34 cm-2 s-1, an average of 40 to 50 pp collisions per bunch crossing are expected. Together with the increase of the center-of-mass collision energy from 8 TeV to 13 TeV, this will create a challenging environment for primary vertex pattern recognition. This contribution explains the ATLAS strategy for primary vertex reconstruction in high pile-up conditions. The new approach is based on vertex seeding with a medical-imaging algorithm, adaptive reconstruction of vertex positions, and iterative recombination of occasional split vertices. The mathematical foundation and software implementation of the method are described in detail. Monte Carlo-based estimates of vertex reconstruction performance for LHC run-II are presented.
Kirill Prokofiev (The Hong Kong University of Science and Technology (HK))
Andrew Mark Wharton (Lancaster University (GB)) Dr Guennadi Borissov (Lancaster University (GB)) Kathryn Grimm (Lancaster University (GB)) Lars Egholm Pedersen (University of Copenhagen (DK)) Matthew Scott Rudolph (University of Toronto (CA)) Olivier Arnaez (CERN) Simone Pagan Griso (Lawrence Berkeley National Lab. (US))