CP Violation in hadronic B-decays at LHCb

The LHCb Experiment is an experiment dedicated to precision measurements of CP violation and rare decays in the heavy flavour sector. In $b$-physics LHCb profits from the large $b\bar{b}$ production cross section that gives access to a high statistics sample of the full spectrum of $b$-hadrons. Due to the very large total cross section an effective on-line event selection is required where the rate is reduced by a first level hardware trigger and further by two levels of software triggers. LHCb is specifically adapted to trigger on the hadronic final states discussed in this paper which is particularly difficult in the high-multiplicity environment of a hadron machine. The measurements of hadronic B-decays in LHCb can roughly be divided into two classes, decays dominated by tree diagrams and decays with a significant contribution from loop processes. The former is generally insensitive to processes beyond the Standard Model (SM), whereas the latter is not. The tree amplitude of decays into final states containing only pions, kaons and protons are proportional to the Cabibbo-Kobayashi-Maskawa (CKM) element $|V_{ub}|$. Hence these decays have a significant contribution from loop processes due to the small magnitude of this factor. First results from these charmless decays are discussed in Section 2. Decays containing charmed hadrons in the final states are dominated by tree diagrams. LHCb has a rich programme of studying these decays, notably it can determine the pure SM value of the CKM angle $\gamma$. Due to space constraints this topic will not be covered in this paper.