Poszukiwanie łamania liczby barionowej i leptonowej w rozpadach ciężkich barionów oraz badanie tła dla poszukiwań długożyciowych cząstek egzotycznych

Abstract

The thesis describes searches for baryon and lepton number violation in X b → K−µ + (X b = Λ b , Ξ 0 b ) decays. The study is performed in the LHCb experiment using data sample corresponding to an integrated luminosity of 3.0 fb− 1 of proton-proton collisions at the centre-of-mass energy of 7 TeV (8 TeV), collected in 2011 (2012), respectively. No statistically significant signal of the decays in question has been found. As a result, the upper limits have been set: B (Λ b → K−µ + ) < 3.6 × 10− 9 and B (Ξ 0 b → K−µ + ) < 1.8 × 10− 8 at the 95% confidence level. The second part of the thesis presents the background studies for exotic searches. The measurement of σ(bb) and σ(cc) production cross-sections with b − (c − ) hadron inclusive final states has been performed with data collected by the LHCb experiment in 2010 in proton-proton collisions at the centre-of- mass energy of 7 TeV. The author of this thesis has prepared the interface to the Next-To-Leading-Order POWHEG simulation framework into the LHCb software chain. All the kinematic characteristics of the hadron production in proton-proton collisions have been studied. The resulting angular and momentum correlations indicate a possible contribution from other mechanisms of bb production than the flavour creation, mainly the gluon splitting.