Related papers: Lepton universality test with Kl2 decays at NA62 e…

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…

The NA62 experiment, proposed to measure the very rare decay K+ to pi+ nu nubar at the CERN SPS with 10% accuracy, aims to collect about 80 events in two years of data taking, keeping background contamination lower than 10%. This paper…

The $K^+\rightarrow \pi^+ \nu \bar \nu$ decay is theoretically one of the cleanest meson decays and so a good place to look for indirect effects of new physics complementary to LHC searches. The NA62 experiment at CERN is designed to…

The LHCb collaboration has recently presented their result on R_K = BR(B+ -> K+ mu+ mu-)/ BR(B+ -> K+ e+ e-) for the dilepton invariant mass bin m_{ll}^2 = 1-6 GeV^2 (l = mu, e). The measurement shows an intriguing 2.6 sigma deviation from…

KLOE has measured most decay branching ratios of Ks, Kl and K+/- mesons. It has also measured the Kl and the K+- lifetime and determined the shape of the form factors involved in kaon semileptonic decays. We present in the following a…

Using a sample of 122 million Upsilon(3S) decays collected with the BaBar detector at the PEP-II asymmetric energy collider at the SLAC National Accelerator Laboratory, we measure the ratio…

Recent measurements of kaon decays provide new information about CKM unitarity, lepton universality, and discrete symmetries. KLOE-2, the proposed extension of the kaon physics program at Frascati, will extend the world data set on kaon…

$K\rightarrow \pi\nu \bar\nu$ is one of the theoretically cleanest meson decay where to look for indirect effects of new physics complementary to LHC searches. The NA62 experiment at CERN SPS is designed to measure the branching ratio of…

The NA62 experiment at CERN will measure the branching ratio of the K+ -> pi+ nu nubar decay with a precision of 10%, collecting about 100 events in two years of run. This paper will review the design of the experiment, the strategy for the…

We present recent tests of lepton universality as crucial probes of the Standard Model in semileptonic $B$-meson decays at Belle II. All presented analyses use a data sample collected at the $\Upsilon(4S)$ resonance by the Belle II…

We present a measurement of the ratio $R_\mu = \mathcal{B}(\tau^-\to \mu^-\bar\nu_\mu\nu_\tau) / \mathcal{B}(\tau^-\to e^-\bar\nu_e\nu_\tau)$ of branching fractions $\mathcal{B}$ of the $\tau$ lepton decaying to muons or electrons using…

The quantity R_K = Gamma(K -> e nu)/Gamma(K -> mu nu) studied by the experiment NA62 at CERN is known to probe lepton-flavour violating (LFV) parameters of the Minimal Supersymmetric Standard Model (MSSM). A non-zero parameter…

The first test of lepton flavor universality between muons and electrons using $B^+ \to K^+\pi^+\pi^-\ell^+\ell^-$ ($\ell=e,\mu$) decays is presented. The measurement is performed with data from proton-proton collisions collected by the…

In the Standard Model extended by sterile neutrinos, modified W-l-nu couplings arise, which are able to induce a tree-level enhancement to lepton flavour universality violation in kaon decays. The additional mixing between the active…

Precise measurements of semileptonic kaon decay rates at KLOE provide the measurement of the CKM mixing matrix element \vus\ and information about lepton universality. Leptonic kaon decays provide an independent measurement of…

The main aim of the NA62 experiment at CERN is to study the rare $K^+ \rightarrow \pi^+ \nu \bar{\nu}$ decay and measure its Branching Ratio (BR) with $10%$ precision. Due to its theoretical precision, this decay is an excellent probe to…

The NA62 experiment at CERN has collected a large sample of $K^+$ and $\pi^+$ decays in flight during Run 1 in 2016--2018 and the ongoing Run 2 which started in 2021. Searches for the decays $K^+\rightarrow\pi^+X$ and $\pi^+\rightarrow…

The Belle Collaboration presented three recent Belle analyses: The search for $B\rightarrow l\nu\gamma$ ($l = e, \mu$) with improved hadronic tagging, the search for $B\rightarrow \mu \nu_\mu$ with inclusive tagging and the test of lepton…

The first search for the lepton number violating decay $K^+\to\pi^0\pi^-\mu^+e^+$ and lepton flavour violating decays $K^+\to\pi^0\pi^+\mu^-e^+$, $K^+\to\pi^0\pi^+\mu^+e^-$ has been performed using a dataset collected by the NA62 experiment…

Lepton universality, meaning the equal coupling of the electroweak gauge bosons to the different lepton flavours, is a central property of the Standard Model (SM). Tests of lepton universality in ratios of rates of $b\to s\ell^+\ell^-$…