Search for the rare decays B0(s) -- μ+ μ- and K0s -- μ+ μ- with 1 fb-1 at LHCb
- José Angel Hernando Morata Director
- Bernardo Adeva Andany Co-director
Defence university: Universidade de Santiago de Compostela
Fecha de defensa: 26 October 2012
- Pierluigi Campana Chair
- Cibrán Santamarina Ríos Secretary
- Frederic Teubert Committee member
- Thomas Ruf Committee member
- Carlos Pajares Vales Committee member
Type: Thesis
Abstract
This thesis is devoted to the explanation of the searches for the very rare decays B0 (s) ! + and K0 S ! + , performed using the 1 fb1 of data taken by LHCb during 2011 from the LHC proton{ proton collisions at an energy of p s=7 TeV. The most relevant theory aspects concerning these searches will be presented. Furthermore, the LHCb experiment will be described, and some of its most interesting results in the rare decays area reported. The B0 (s) ! + search has not resulted in any signal excess above background, but has produced world best upper limits in the branching ratios of both channels: B(B0 ! + ) < 1:0 109 and B(B0 s ! + ) < 4:5 109, both at 95% con dence level. Finally, no signi cant signal excess has been found in the search for K0 S ! + neither, and again an upper limit on its branching ratio has been set: B(K0 S ! + ) < 11:2 109 at 95% con dence level. This upper limit is a factor of 35 better than the previous world best.