Related papers: Kaon experiments at CERN: NA48 and NA62
In kaon physics, several new precision measurements on flavour variables and CP violation have performed in the recent years. Presented are a new precise determination of the CKM parameter |V_us|, which combines the results of all…
A precision test of lepton flavour universality has been performed by measuring the ratio RK of kaon leptonic decay rates K+ --> e+nu and K+ --> mu+nu in a sample of 59813 reconstructed K+ --> e+nu candidates with (8.71 +- 0.24)% background…
The main purpose of the NA62 experiment is to measure the branching ratio of the (ultra) rare decay $K+ \rightarrow {\pi}+{\nu}\bar{\nu}$ with the precision of 10% collecting about 100 events with the Standard Model branching fraction in 3…
A search for heavy neutral lepton ($N$) production in $K^+\to e^+N$ decays using the data sample collected by the NA62 experiment at CERN in 2017--2018 is reported. Upper limits of the extended neutrino mixing matrix element $|U_{e4}|^2$…
A sample of 3984 candidates of the $K^+\to\pi^+\gamma\gamma$ decay, with an estimated background of $291\pm14$ events, was collected by the NA62 experiment at CERN during 2017-2018. In order to describe the observed di-photon mass spectrum,…
Searches for heavy neutrinos can be successfully performed by fixed target experiments at the CERN SPS. New results obtained by the NA62 and NA48/2 kaon experiments are summarized in this paper. The physics potential of future projects…
The rare kaon decay $K_L\to\pi^0\nu\bar{\nu}$ is extremely sensitive to new physics, because the contribution to this decay in the Standard Model (SM) is highly suppressed and known very accurately; the branching ratio is $3\times 10^{-11}$…
Several recent results from the NA48 experiment are presented: a measurement $|\eta_{+-}|$, search for CP violating phenomena in $K^\pm\to3\pi$ decays, and a measurement of $|V_{us}|$.
A precise measurement of the direct CP violating charge asymmetry parameter $A_g$ in $K^\pm\to\pi^\pm\pi^+\pi^-$ decays by the NA48/2 experiment at CERN SPS is presented. The experiment has been designed not to be limited by systematic…
Precision data on Kl3 and Kl2 decay rates and form factors allow us to perform significant tests of lepton universality and to constrain the strength of non-standard interactions. The present status of these tests and new physics searches…
Soon the NA62 experiment will start looking for the rare K+ ---> pi+ nu nu bar decay. In this talk, its theoretical interests, together with those of the neutral rare decays KL ---> pi0 nu nu bar, KL ---> pi0 e+ e-, and KL ---> pi0 mu+ mu-,…
Precise measurements of the branching ratios for the flavor-changing neutral current decays $K\to\pi\nu\bar{\nu}$ can provide unique constraints on CKM unitarity and, potentially, evidence for new physics. It is important to measure both…
The NA62 experiment at CERN SPS started physics data taking this year with the aim to measure the ultra-rare decay $K^+\to\pi^+\nu\bar{\nu}$. The experiment consists of a large number of subsystems to reach the goal of 10% accuracy and less…
The direct CP violation parameter Re($\epsilon'\epsilon$) has been measured from the decay rates of neutral kaons into two pions using the NA48 detector at the CERN SPS. The 2001 running period was devoted to collecting additional data…
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…
Recent results and future plans of kaon physics are reviewed. Topics include CP violation, rare decays, light neutral-boson search, lepton flavor universality, and CPT and QM tests.
Recent results from the NA48/2 experiment are presented. The $\pi\pi$ scattering lengths $a_0^0$ and $a_0^2$ have been extracted from the cusp in the $M_{00}^2$ distribution of $K^\pm \to \pi^\pm \pi^0 \pi^0$ decays and from the $K^\pm \to…
We report a measurement of the direct CP violation asymmetry parameter $A_g$ in charged kaon decays $K^\pm\to\pi^\pm\pi^+\pi^-$ by the NA48/2 experiment at the CERN SPS. The experiment has been designed not to be limited by systematics in…
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…
A search for heavy neutral lepton ($N$) production in $\pi^+\to e^+ N$ in-flight decays using data collected by the NA62 experiment at CERN in 2017-2024 is reported. Upper limits for the extended neutrino mixing matrix element $|U_{e4}|^2$…