Aachen 2019 – scientific programme
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T: Fachverband Teilchenphysik
T 63: Flavorphysik II
T 63.1: Talk
Wednesday, March 27, 2019, 16:00–16:15, S15
Measurement of the ratio RK∗ 0 using Run 1 + 2 data of the LHCb experiment — •Stephan Escher, Sarah Beranek, Christoph Langenbruch, Stefan Schael, and Eluned Smith — RWTH Aachen, Germany
In the Standard Model (SM) of particle physics flavour-changing neutral-current processes are forbidden at tree-level and can only occur in electroweak loop diagrams. Therefore, b→ s transitions are rare and sensitive to heavy particles beyond the SM. In this theory the coupling of gauge bosons to leptons are independent of their flavour, which is known as lepton flavour universality (LFU). Thus, the RK∗ 0 ratio, defined as RK∗ 0=B(B0→ K∗ 0µ+µ−)/B(B0→ K∗ 0e+e−), is predicted to be unity in the SM (neglecting lepton mass effects). The existence of new particles, that couple differently to electrons and muons, could influence the RK∗ 0 ratio significantly and lead to deviations from unity.
To this date, the most precise measurement of RK∗ 0 is performed by the LHCb collaboration using Run 1 data showing a deviation of 2.4−2.5 standard deviations (σ) from the SM expectations.
This talk will present the strategy of the analysis using the combined Run 1 and 2 LHCb data sample, which will allow for a more precise determination of RK∗ 0. Particular emphasis will be on the study and control of backgrounds.