Related papers: Rare Kaon Decays
We review some recent theoretical results on radiative rare kaon decays. Particular attention is devoted to the channels $K\to \pi l\bar{% l}$ and $K\to \pi \pi \gamma$, where we are (or might be) able to extract the short distance…
We update the Standard Model predictions for the rare decays $K^+\to\pi^+\nu\bar\nu$ and $K_L\to\pi^0\nu\bar\nu$. In view of improved limits on $B_s$--$\bar B_s$ mixing we derive a stringent and theoretically clean Standard Model upper…
A search for additional evidence for the rare kaon decay K^+ --> pi^+ nu nubar has been made with a new data set comparable in sensitivity to the previous exposure that produced a single event.
We report the first search for the $K_L \to \pi^0 \gamma$ decay, which is forbidden by Lorentz invariance, using the data from 2016 to 2018 at the J-PARC KOTO experiment. With a single event sensitivity of $(7.1\pm 0.3_{\rm stat.} \pm…
In the first year of physics run, the E949 experiment at Brookhaven National Laboratory has already collected $1.8\times 10^{12}$ kaons stopping in the target. Additional evidence for the rare charged kaon decay $K^+\to\pi^+\nu\bar{\nu}$…
We report a first, complete lattice QCD calculation of the long-distance contribution to the $K^+\to\pi^+\nu\bar{\nu}$ decay within the standard model. This is a second-order weak process involving two four-Fermi operators that is highly…
The rare decay $K^\pm\to\pi^\pm\gamma\gamma$ has been recently measured from data samples collected by the NA48/2 and NA62 experiments at CERN. These measurements are presented, including model-independent spectrum measurements and fits to…
We review some recent theoretical results on rare kaon decays. Particular attention is devoted to establish the short distance (direct CP violating) contribution to K_L => \pi^0 e \bar{e}. This is achieved by a careful study of the long…
The rare decay $K_L \!\to\! \pi^0 \nu \overline{\nu}$ was studied with the dataset taken at the J-PARC KOTO experiment in 2016, 2017, and 2018. With a single event sensitivity of $( 7.20 \pm 0.05_{\rm stat} \pm 0.66_{\rm syst} ) \times…
We search for the rare flavor-changing neutral-current decay $B^+ \to K^+ \nu \bar{\nu}$ in a data sample of 82 fb$^{-1}$ collected with the {\sl BABAR} detector at the PEP-II B-factory. Signal events are selected by examining the…
Recent results from the NA48/2 and NA62 kaon decay-in-flight experiments at CERN are presented. A precision measurement of the helicity-suppressed ratio RK of the K+- to e+- nu and K+- to mu+- nu decay rates has been performed using the…
The rare kaon decay K^+ --> \pi^+ \nu \bar{\nu} is considered in the framework of the models based on the SU(3)_C X SU(3)_L X U(1)_N (3 - 3 - 1) gauge group. It is shown that a lower bound of the Z' mass in the 3 - 3 - 1 model with…
Measuring the rate at which the long-lived, neutral kaon decays into a neutral pion, neutrino, and anti-neutrino allows physicists an opportunity to test precise predictions made by the Standard Model. Differences between theoretical…
We have searched for the decay $K^+ \to \pi^+ \nu \bar\nu$ in the kinematic region with pion momentum below the $K^+ \to \pi^+ \pi^0$ peak. One event was observed, consistent with the background estimate of $0.73\pm 0.18$. This implies an…
The main physics goal of the NA62 experiment at CERN is to precisely measure the branching ratio of the kaon rare decay $K^+\rightarrow \pi^+ \nu \bar\nu$. This decay is strongly suppressed in the Standard Model and its branching ratio is…
Rare kaon decays provide sensitive tests of new physics. In this work, we focus on scalar and pseudoscalar operators, analysing the $K\to \pi \ell^+\ell^-$ and $K\to \ell^+\ell^-$ decays. We highlight the complementary role of different…
Recent results a future prospects of the NA62 experiment at CERN SPS are presented. The NA62 experiment performed the most precise measurement of the ratio $R_K$ of the $K^+\rightarrow e^\pm\nu$ and K^+\rightarrow \mu^\pm\nu$ decay rates…
The following proceedings contain a theory perspective on rare Kaon decays. I review rare kaon decays in the LHC era: we discuss interplay with B-anomalies and possible New Physics in direct CP violation in $K\to 2\pi$: very rare kaon…
Rare $K \to \pi \nu \bar \nu$ decays, being dominated by short distance contributions within the Standard Model (SM), open a window for New Physics (NP) searches at low energies. The $ K \to \pi \nu \bar\nu $ branching ratios are expected…
A search for the $K^{+} \to \pi^{0}\pi^{0}\pi^{0}e^+\nu$ decay is performed by the OKA collaboration. The search is based on $3.65 \times 10^9 ~ K^+$ decays. No signal is observed. The upper limit set is $BR(K^{+} \to…