Heidelberg 2015 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 74: Heavy Ion Collisions and QCD Phases 11

HK 74.5: Talk

Friday, March 27, 2015, 15:45–16:00, T/SR14

Study of the Applicability of Markov Chain Monte Carlo Methods to the Statistical Separation of Electron Sources via the Impact Parameter for ALICE — •Manuel Wittner for the ALICE collaboration — Physikalisches Institut, Universität Heidelberg, Heidelberg

One particularly interesting measurement detected by the ALICE set-up at the LHC are electrons from charm and beauty hadron decays. Heavy quarks originate from initial hard scattering processes and thus experience the whole history of a heavy ion collision. Therefore, they are valuable probes to study the mechanisms of energy loss and hadronization in the hot and dense state of matter, that is expected to be formed in a heavy-ion collision at LHC. One important task is the distinction of the different electron sources, for which a method was developed. Hereby, the impact parameter distribution of the measurement data is compared with impact parameter distributions for the individual sources, which are created through Monte Carlo simulations. Afterwards, a maximum likelihood fit is applied. However, creating a posterior distribution of the likelihood according to Bayes’ theorem and sampling it with Markov Chain Monte Carlo algorithms provides several advantages, e.g. a mathematically correct estimation of the uncertainties or the usage of prior knowledge. Hence for the first time in this particular problem, a Markov Chain Monte Carlo algorithm, namely the Metropolis algorithm, was implemented and investigated for its applicability in heavy flavor physics. First studies indicate its great usefulness in this field of physics.