Precision tests of the Standard Model with leptonic and semileptonic kaon decays

We present a global analysis of leptonic and semileptonic kaon decays data, including all recent results by BNL-E865, KLOE, KTeV, ISTRA+, and NA48. Experimental results are critically reviewed and combined, taking into account theoretical (both analytical and numerical) constraints on the semileptonic kaon form factors. This analysis leads to a very accurate determination of Vus and allows us to perform several stringent tests of the Standard Model.We present a global analysis of leptonic and semileptonic kaon decays data, including all recent results by BNL-E865, KLOE, KTeV, ISTRA+, and NA48. Experimental results are critically reviewed and combined, taking into account theoretical (both analytical and numerical) constraints on the semileptonic kaon form factors. This analysis leads to a very accurate determination of Vus and allows us to perform several stringent tests of the Standard Model

Review of Kaon Physics at CERN and in Europe

The Kaon physics program at CERN and in Europe will be presented. I will first give a short review of recent results form the NA48/2 and NA62 experiments, with special emphasis to the measurement of RK , the ratio of Kaon leptonic decays rates, K → eν and K → μν, using the full minimum bias data sample collected in 2007-2008. The main subject of the talk will be the study of the highly suppressed decay K → πνν. While its rate can be predicted with minimal theoretical uncertainty in the Standard Model (BR ∼ 8 × 10−11), the smallness of BR and the challenging experimental signature make it very difficult to measure. The branching ratio for this decay is thus a sensitive probe of the flavour sector of the SM. The aim of NA62 is the measurement of the K → πνν BR with ∼ 10% precision in two years of data taking. This will require the observation of 10K decays in the experiment's fiducial volume, as well as the use of high-performance systems for precision tracking, particle identification, and photon vetoing. These aspects of the experiment will also allow NA62 to carry out a rich program of searches for lepton flavour and/or number violating K decays. Data taking will start in October 2014. The physics prospects and the status of the construction and commissioning of the NA62 experiment will be presented. In the last part of the talk I will report on Kaon physics results and prospects from other experiments at CERN (e.g. LHCb) and in Europe (e.g. KLOE and KLOE-2) and briefly mention the status in US

A stringent test of μ − e universality in K→lνK\to l\nu decays by NA62 at CERN

New interest has arisen in measuring the ratio $R_K$ = $K_{e}2/K_{/mu}2$, as recent high-intensity kaon experiments arc able to largely improve the precision. With ~150000 collected Ke2 decays, the NA62 experiment has increased the world $K_{e}2$ sample by an order of magnitude, allowing a stringent test of $\mu - e$ lepton universality. Here, we describe the experiment and summarize the status of the analysis based on ~40 % of the total data sample taken in 2007

Messung der direkten CP-Verletzung im System der neutralen Kaonen mit dem NA48-Detektor: Analyse der Daten aus dem Jahr 2001

In this thesis the determination of Re(ε'/ε) by means of measurements of the width ratios of the decays KL,S0→π+π- and KL,S0→π0π0, studied on K0L,S-beams at CERN, is described. A value of Re(ε'/ε)=(13.3±2.4(stat.)±1.9(syst.)) x 10-4 was obtained

Kaon Physics at CERN – Recent Results from the NA48/2 and NA62 Experiments

This letter presents recent results from the kaon experiments NA48/2 and its successor NA62 at CERN. With samples of 2.5 × 106 Kµ3± and 4.0 × 106 Ke3± events collected by NA48/2 in 2004, precise measurements of the form factors were performed. The Chiral Perturbation Theory was tested through a new study of K± → π±γγ decays based on data taken with minimal trigger conditions. Using the beam line and detector of NA48/2 in the years 2007-2008, NA62 performed a precison measurement of the helicitysuppressed ratio of the charged kaon leptonic decay rates K± → e+ν and K± → μ+ν Using the full data set, which is about ten times larger than the previous world data sample, the total uncertainty on this ratio is only 0.4%, representing a precision test of μ – e lepton universality. Finally, the main stage of the NA62 experiment is presented. The planned measurement of the ultra rare decay K+ → π+$v\bar v$ at 10% precision will provide a powerful test of the Standard Model. The experimental challenges to reach this goal require new detectors with exceptional performances

Search for heavy neutrinos in K+→μ+νμK^+ \rightarrow \mu^+ \nu_{\mu} decays

International audienceThe NA62 experiment recorded a large sample of K+→μ+νμ decays in 2007. A peak search has been performed in the reconstructed missing mass spectrum. In the absence of a signal, limits in the range 2×10−6 to 10−5 have been set on the squared mixing matrix element |Uμ4|2 between muon and heavy neutrino states, for heavy neutrino masses in the range 300–375 MeV/ c2 . The result extends the range of masses for which upper limits have been set on the value of |Uμ4|2 in previous production search experiments