Related papers: $K\to \mu^{+} \mu^{-}$ as a third kaon golden mode
The rare decays $K^0_L \to\mu^+\mu^-$ and $K^0_S \to\mu^+\mu^-$ have long been regarded as difficult channels to extract short-distance physics because they are dominated by long-distance contributions via two-photon exchanges. A…
The $K\to\mu^+\mu^-$ decay is often considered to be uninformative of fundamental theory parameters since the decay is polluted by long-distance hadronic effects. We demonstrate that, using very mild assumptions and utilizing time-dependent…
We analyze the New Physics sensitivity of a recently proposed method to measure the CP-violating ${\cal B}(K_S\to\mu^+\mu^-)_{\ell=0}$ decay rate using $K_S - K_L$ interference. We present our findings both in a model-independent EFT…
The $K \rightarrow \mu\mu$ decays have recently been identified as another golden kaon physics mode alongside the rare $K \rightarrow\pi\nu\bar{\nu}$ processes. These golden modes provide precision tests of the Standard Model with very high…
We review a new method in order to determine the parameter $\bar{\eta}$ of the Cabibbo-Kobayashi-Maskawa matrix from $K\rightarrow \mu^+\mu^-$ decays, using interference effects in the time-dependent decay rate. Furthermore, we discuss a…
Motivated by new precise results on several $K_L$ decays, sensitive to the ${K_L \to \gamma \gamma}$ form factor, we present a new analysis of the $K_L\to \mu^+\mu^-$ long-distance amplitude based on a semi-phenomenological approach.…
Rare Kaon decays provide sensitive probes of short distance physics. Among the most promising modes are the K+ --> pi+ nu anti-nu and K(L) --> pi0 nu anti-nu modes due to their theoretical cleanness and the dedicated experiments, NA62 and…
Evidence of the $K^+\to\mu^+\nu\bar\nu\nu$ decay was searched for using E949 experimental data with an exposure of $1.70\times 10^{12}$ stopped kaons. The data sample is dominated by the backgrond process $K^+\to\mu^+\nu_\mu\gamma$. An…
Rare K decays provide for very clean tests of the Standard Model, and are especially suited to search for New Physics signal. In this talk, recent progresses in the estimation of long-distance effects induced by light quarks in KL to pi0…
The rare kaon decays K_L -> pi^0 nu {bar nu}, K^+ -> pi^+ nu {bar nu}, K_L -> pi^0 e^+ e^- and K_L -> pi^0 mu^+ mu^- are theoretically very clean and, being strongly CKM suppressed, highly sensitive to New Physics (NP). Recent Flavour…
The decay $K_S \to (\mu^+\mu^-)_{\ell=0}$, with the final muon pair in an angular-momentum zero state, is a sensitive probe of short-distance physics. It has recently been shown how to extract this branching ratio from neutral kaon decay…
A new analysis of the long-distance two-photon dispersive amplitude of K_L -> mu^+ mu^- is presented. We introduce a phenomenological parameterization of the K_L -> gamma^* gamma^* form factor, constrained at low energies by K_L -> gamma…
We have examined the physics and the experimental feasibility of studying various kaon decay processes in which the polarization of a muon in the final state is measured. Valuable information on CP violation, the quark mixing (CKM) matrix,…
A rare decay $K_L \to \mu^+ \mu^- $ has been measured precisely, while a rare decay $K_S \to \mu^+ \mu^- $ will be observed by an upgrade of the LHCb experiment. Although both processes are almost CP-conserving decays, we point out that an…
The decay $B^{\pm}\to DK^{\pm}$ followed by the subsequent decay of the $D$ meson into final states involving a neutral kaon can be used to determine the CKM angle $\gamma$. We study CP violation effects due to mixing and decay of the final…
The K^+ \to \pi^0 \mu^+ \nu \gamma ($K_{\mu 3 \gamma}$) decay has been measured with stopped positive kaons at the KEK 12 GeV proton synchrotron. A $K_{\mu 3 \gamma}$ sample containing 125 events was obtained. The partial branching ratio…
The interplay between short- and long-distance contributions to the K_L-->mu+ mu- decay amplitude is analyzed. The long-distance piece is estimated using chiral perturbation theory techniques and large-N_C considerations, leading to a…
Rare kaon decays offer a powerful tool for investigating new physics in $s\to d$ transitions. Currently, many of the interesting decay modes are either measured with rather large uncertainties compared to their theoretical predictions or…
We review some recent theoretical results on rare kaon decays. Particular attention is devoted to find Standard Model tests. This is theoretically easy in $K\to \pi \nu \bar{\nu}$, while a careful study of the long distance contributions is…
The rare $K \to \pi \nu \bar{\nu}$ decay modes and the parameter $\epsilon_K$ that measures CP violation in Kaon mixing are sensitive probes of physics beyond the standard model. In this article we provide the updated standard-model…