The LHCb experiment is designed to fully exploit the large number of b hadrons expected at the LHC energy and luminosity. The experiment is equipped with particle identification devices and can efficiently trigger events with different B-meson final states, allowing systematic studies of CP violation and other rare phenomena in the b hadron system with a high precision which could reveal physics beyond the Standard Model.
1. PHYSICS CASE
Well established CP violation phenomena in the neutral kaon system can be described in a consistent manner within the framework of the Standard Model[l]. However, no real precision test has been made due to the large uncertainties in evaluating the effect of hadronic interactions. The Standard Model can make very precise predictions for CP violation in some B-meson decay modes without hadronic uncertainties once all the four parameters of the Cabibbo-Kobayashi-Maskawa[2] (CKM) mass mixing matrix become known. Therefore, it is now widely accepted that the B-meson system provides an ideal place for testing the Standard Model for CP violation.
BaBar, Belle, CDF, DO and HERA-B are the experiments which will soon establish CP violation in B~ and B~-+J/ยขKs decays if CP violation is indeed largely due to the Standard Model. In the framework of the Standard Model, this will already allow to test the consistency of the determined CKM parameters. The situation becomes more complicated if physics beyond the Standard :Model is present and CP violation measurements with other than the J/ยขKs final states become necessary as demonstrated in the following sections.
Interest in CP violation is not limited to elementary particle physics. It is one of the three necessary ingredients to generate observed excess of matter over antimatter in the universe [3]. The amount of CP violation which can be generated by the Standard Model appears to be insufficient for explaining the observed matter-antimatter asymmetry in the universe [4], giving a strong motivation to search for new physics.