Searching for new physics in b → sℓ\(^+\)ℓ\(^-\) transitions at the LHCb experiment

[摘要] Flavour Changing Neutral Currents are transitions between different quarks with the same charge such as b → s processes. These are forbidden at tree level in the Standard Model (SM) but can happen through loop diagrams, which causes the branching ratio of this type of decays to be small, typically ~ 10\(^-\)\(^6\) or less. Particles beyond the SM can contribute in the loops enhancing the branching fractions of these decays, which are therefore very sensitive new physics. In this work two analysis of semileptonic b → sℓ\(^+\)ℓ\(^-\)decays are presented. In the first, ∧\(^0\)\(_b\) → ∧μ\(^+\)μ\(^-\)decays are analysed to measure their branching fraction as a function of the square of the dimuon invariant mass, q\(^2\). An angular analysis of these decays is also performed for the first time. Secondly, B\(^0\)→ K\(^*\)\(^0\)ℓ\(^+\)ℓ\(^-\) decays are analysed measuring the R\(_k\)\(_*\)\(_0\) ratio between the muon, B\(^0\) → K\(^*\)\(^0\)μ\(^+\)μ\(^-\), and electron, B\(^0\) → K\(^*\)\(^0\)e\(^+\)e\(^-\), channels, which is interesting as it is largely free from uncertainties due to the knowledge of the hadronic matrix elements.

[发布机构] University:University of Birmingham;Department:School of Physics and Astronomy

[关键词] Q Science;QC Physics