Mainz 2014 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 92: Flavour (Theorie/Experiment) 2

T 92.3: Vortrag

Mittwoch, 26. März 2014, 17:15–17:30, GFH 01-701

Measurement of semileptonic kaon decay rates with NA62 — •Mario Vormstein — Institut für Physik, Johannes Gutenberg - Universität, Mainz

The increasing precision with which the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix can be tested is an important tool for exploring the limits of the Standard Model. One such unitarity relation is |V_ud |² + |V_us|² + |V_ub|² = 1 whose uncertainty is dominated by the precision on |V_us |. The |V_us| element can be determined in the most accurate and theoretically cleanest way by measuring the decay rate of semileptonic decays of the kaon (K_l3=K^±→ π⁰ l^±ν with l=e,µ). Secondly a stringent constraint on new physics can be given by testing lepton universality. Measuring the ratio R=Γ(K_µ3) /Γ(K_e3) offers the possibility to determine |V_us| and to test e-µ lepton universality.
The NA62 collaboration acquired data in 2007 at the Super-Proton-Synchrotron (SPS / CERN) with the NA48 detector. This talk will give an overview of the R=Γ(K_µ3) /Γ(K_e3) analysis of the collected data. The selection and reconstruction of signal decays, suppression of background decays and comparison between data and Monte Carlo simulation is discussed.