Related papers: Neutral pion form factor measurement at NA62
Rare kaon decays are excellent probes of light, new weakly-coupled particles. If such particles $X$ couple preferentially to muons, they can be produced in $K\to \mu \nu X$ decays. In this letter we evaluate the future sensitivity for this…
The rate of the beta decay of neutral kaons is calculated within the meson dominance approach taking into account the relation between the KK\rho and \pi\pi\rho coupling constants which follows from the vector meson dominance in…
The standard model (SM) of particle physics is spectacularly successful, yet the measured value of the muon anomalous magnetic moment $(g-2)_\mu$ deviates from SM calculations by 3.6$\sigma$. Several theoretical models attribute this to the…
Precision measurements of observables in neutron $\beta$-decay are used to test the Standard Model description of the weak interaction and search for evidence of new physics. The Nab experiment at the Fundamental Neutron Physics Beamline at…
A sample of $1.3 \times 10^5$ $K^+ \to \pi^0 e^+ \nu \gamma$ candidates with less than 1% background was collected by the NA62 experiment at the CERN SPS in 2017-2018. Branching fraction measurements are obtained at percent relative…
The decay rate of the neutral long-lived K meson into the e+ e- e+ e- final state has been measured with the NA48 detector at the CERN SPS. Using data collected in 1999, a total of 132 events has been observed with negligible background.…
Kaon experiments are now focusing on searching for new physics beyond the standard model. For example, CERN NA62, J-PARC KOTO and J-PARC TREK-E36 experiments are starting up to study K->pi nu nu-bar decay modes, a lepton flavor violation,…
The NA62 experiment at SPS is a continuation of the long standing CERN kaon physics program. The high statistics and the unprecedent precision allow to probe the Standard Model and test the description of the strong interactions at low…
The ratio $R_K = \Gamma(K^{\pm}\to e^{\pm}\nu(\gamma)) / \Gamma(K^{\pm}\to\mu^{\pm}\nu(\gamma))$ provides a powerful probe of the structure of weak interactions. It is calculated with very high precision within the Standard Model, but…
Accelerator-based experiments reliant on charged pion and kaon decays to produce muon-neutrino beams also deliver an associated powerful flux of muons. Therefore, these experiments can additionally be sensitive to light new particles that…
We report here a measurement of form factors of $K^{\pm}_{\mu 3}$ decay by the NA48/2 experiment at CERN. Using a sample of 3.4$\times10^6$ events we provide preliminary form factor values according to various parametrizations. The slope of…
We report on the measurement of the direct emission (DE) and interference (INT) terms of the K\pm -> \pi\pm\pi^0 g decay by the NA48/2 experiment at the CERN SPS. From the data collected during 2003 and 2004 about 600k such decay candidates…
At large momentum transfers the photon interacts with the charges and spins of the constituent partons in a hadron. It is expected that the neutral kaon can acquire finite electromagnetic form factors because its wave function is affected…
The long-term goal of NA62 is to measure the ultra rare K+/- -> pi+/- nu anti-nu decay with a sensitivity of 10^-12 per event. This is done by using the decay - in - flight technique which allows a signal acceptance of ~10% . The aim is to…
A model-independent expression for the Dalitz plot of the semileptonic decays of a neutral kaon $K_{\mu 3}^0$, including radiative corrections to order $\mathcal{O}[(\alpha / \pi )(q/M_1)]$, where $q$ is the four-momentum transfer and $M_1$…
The NA48/2 experiment at CERN reports the first observation of the $K^{\pm} \rightarrow \pi^{0} \pi^{0} \mu^{\pm} \nu$ decay based on a sample of 2437 candidates with 15% background contamination collected in 2003--2004. The decay branching…
The study of the neutral current elastic scattering of neutrinos on protons at lower energies can be used as a compelling probe to improve our knowledge of the strangeness of the proton. We consider a neutrino beam generated from pion decay…
In the last few years it has become possible to study low energy pi pi scattering in kaon decays to three pions, thanks to the high statistics measurement of K+- -> pi+- pi0 pi0 decays performed by the NA48/2 experiment at the CERN SPS. At…
We explore kaon decays with missing energy carried away by a massless dark photon, $\bar\gamma$, assumed to have flavor-changing dipole-type couplings to the $d$ and $s$ quarks. We consider in particular the neutral-kaon modes…
The NA62 experiment at CERN reports a search for the lepton number violating decays $K^+\to\pi^-e^+e^+$ and $K^+\to\pi^-\mu^+\mu^+$ using a data sample collected in 2017. No signals are observed, and upper limits on the branching fractions…