Full Offline Reconstruction in Real Time with the LHCb Detector

This document describes the novel, unique in High Energy Physics, real-time alignment and calibration of the full LHCb detector. The LHCb experiment has been designed as a dedicated heavy flavour physics experiment focused on the reconstruction of c and b hadrons. The LHCb detector is a single-arm forward spectrometer, which measures proton-proton interactions at the LHC. The operational bunch crossing rate is several orders of magnitude above the current abilities of data recording and storage. Therefore, a trigger system has been implemented to reduce this rate to an acceptable value. The LHCb trigger system has been redesigned during the 2013–2015 long shutdown,achieving offline-quality alignment and calibration online. It also allows analyses to be performed entirely at the trigger level. In addition, having the best performing reconstruction in the trigger gives the possibility to fully use the particle identification selection criteria and greatly increases the efficiency, in particular for the selection of charm and strange hadron decays. This results in enhancing the physics programme of the LHCb experiment