Related papers: Kaon programme at CERN: recent results
The recent observation of the $K^+ \to \pi^+ \nu\bar\nu$ decay by NA62 is an important milestone in precision flavor physics. Together with evidence of $B^+ \to K^+\nu\bar\nu$ reported by Belle-II, they are the only FCNC decays involving…
The first search for the rare kaon decay $\kppnn$ has been performed by the E391a collaboration at the KEK 12-GeV proton synchrotron. An upper limit of $4.7\times10^{-5}$ at the 90 % confidence level was set for the branching ratio of the…
The K_S \to pi+/- e+ e- decay mode has been investigated using the data collected in 2002 by the NA48/1 collaboration. With about 23k signal events and 59k K_L \to pi+ pi- pi0_D normalization decays, the K_S \to pi+ pi- e+ e- branching…
A search for the lepton flavour violating decays $\tau^- \to l^- K^0_{\scriptscriptstyle S}$ ($l = e$ or $\mu$) has been performed using a data sample corresponding to an integrated luminosity of 469 ${fb}^{-1}$, collected with the…
The kaon sector is characterised by several processes which are under active investigation across different experiments. In this work, we present the global picture that emerges from a study of the different decay modes. We begin by…
Building on the rare pion and muon decay results of the PIBETA experiment, the PEN collaboration has undertaken a precise measurement of B_{\pi e2} = R^\pi_{e/\mu}, the \pi^+ -> e^+\nu(\gamma) decay branching ratio, at the Paul Scherrer…
The MEG experiment took data at the Paul Scherrer Institute in the years 2009--2013 to test the violation of the lepton flavour conservation law, which originates from an accidental symmetry that the Standard Model of elementary particle…
We have searched for the lepton flavor violating decays $\tau^-\to \ell^-\ks$ ($\ell = e {or} \mu$), using a data sample of 281 fb$^{-1}$ collected with the Belle detector at the KEKB $e^+e^-$ asymmetric-energy collider. No evidence for a…
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…
In the Standard Model of particle physics, charged leptons of different flavour couple to the electroweak force carriers with the same interaction strength. This property, known as lepton flavour universality, was found to be consistent…
The decay $K^+\to\pi^+\nu\bar{\nu}$ is highly suppressed in the Standard Model (SM), while its rate can be predicted with minimal theoretical uncertainty. The branching ratio (BR) for this decay is thus a sensitive probe of the flavor…
We search for lepton flavor and lepton number violating tau decays into a lepton (ell = electron or muon) and two charged mesons (h,h' = pi^\pm or K^\pm), tau- -> ell-h+h'- and tau- -> ell+h-h'-, using 671 fb^{-1} of data collected with the…
We report relevant results from NA48 experiment at CERN SPS. NA48 was proposed in 1990 \cite{proposal} to study direct CP violation in $K^0\to\pi\pi$ to a level of accuracy sufficient to resolve the inconclusive status left by the previous…
We present measurements of the branching fractions for the decays $B\to K \mu^{+}\mu^{-}$ and $B\to K e^{+}e^{-}$, and their ratio ($R_{K}$), using a data sample of 711 $fb^{-1}$ that contains $772 \times 10^{6}$ $B\bar{B}$ events. The data…
The NA62 experiment at CERN is designed to measure precisely the rare decay $K^{+} \rightarrow \pi^+ \nu \bar{\nu}$. The intensity and energy of the SPS proton beam used to produce the $K^+$, as well as the hermetic detector coverage and…
We search for lepton-flavor-violating tau decays into three leptons (electron or muon) using 535 fb-1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. No evidence for these decays is observed, and we…
A timely and long-term programme of kaon decay measurements at a new level of precision is presented, leveraging the capabilities of the CERN Super Proton Synchrotron (SPS). The proposed programme is firmly anchored on the experience built…
In the framework of the low-energy effective theory containing in addition to the Standard Model fields heavy neutral leptons (HNLs), we compute the decay rates of neutral and charged kaons into HNLs. We consider both…
A search for the lepton flavour violating decay tau -> mu gamma has been performed using 221.4/fb of data collected at an e+e- centre-of-mass energy of 10.58 GeV with the BABAR detector at the PEP-II storage ring. The search has an…
The experimental program for the study of the rare kaon decays, K -> pnn, is summarized. A review of recent results is provided along with a discussion of prospects for the future of this program. The primary focus of the world-wide kaon…