Ms. Ana Trisovic (CERN, Geneva, Switzerland)
The LHCb experiment is a general purpose spectrometer in the forward region optimized for precision studies of beauty and charm hadron properties. The volumes of data produced by the LHC make it possible to perform such precision measurements with only a fraction of the total LHCb dataset, making it an ideal playground for developing new types of masterclass exercises. We present here LHCb's first foray into the masterclass programme, in which students are taught how to make a 1% precision measurement of the D0 meson lifetime. The students learn to separate D0 mesons from the background in LHCb's vertex detector and build up a signal mass peak, before learning about how to use background sidebands to extract the signal properties in other variables of interest. They then perform a fit to measure the D0 lifetime, and discover that the result is biased by charm produced in the decays of B hadrons, which has an artificially long lifetime compared to charm produced directly in the proton-proton collision. Finally, the students learn how to separate these two kinds of charm based on the D0 mesons distance of closest approach to the primary interaction and obtain a precise measurement in agreement with the world average. We present the software framework developed for this exercise, give a demonstration of the exercise, and discuss plans for the future.
Dr. Vladimir Gligorov (CERN)