Related papers: Testing mu-e universality with Kl2 decays
High precision electroweak tests, such as deviations from the Standard Model expectations of the Lepton Flavor Universality breaking in K->lnu (with l= e or mu), represent a powerful tool to test the Standard Model and, hence, to constrain…
The most recent progress and future prospects in kaon physics are reviewed. Main results are the first observation of the rare decays KS->pi0ee and KS->pi0mumu by NA48, new K+->pinunu event observed by E949 and new precision measurements of…
We present the first measurement of the ratio of branching fractions of inclusive semileptonic $B$-meson decays, $R(X_{e/\mu}) = \mathcal{B}(B\to X \, e \, \nu) / \mathcal{B}(B\to X \, \mu \, \nu)$, a precision test of electron-muon…
A brief overview of the recent measurements of the branching ratio of the rare $K_L^0 \to \mu^+ \mu^-$ decay in the context of their agreement with the Standard Model (SM) is given. It is shown that KEK result well correlates with the SM…
The universality of the weak interactions can be tested in semileptonic $b \to c$ transitions, and in particular in the ratios $R(D^{(*)}) \equiv \Gamma(B \rightarrow D^{(*)} \tau \nu )/\Gamma(B \rightarrow D^{(*)} \ell \nu )$ (where $\ell…
The full parameter space of supergravity grand unified theory with $SU(5)$ type $p \rightarrow \bar{\nu} K$ proton decay is analysed using renormalization group induced electroweak symmetry breaking under the restrictions that the universal…
The $B\to K^*\mu\mu$ decay exhibits deviations with respect to Standard Model expectations and the measurement of the ratio $R_K$ hints at a violation of lepton-flavour universality in $B\to K\ell\ell$ transitions. Both effects can be…
Recent results by the NA48 collaboration on neutral kaons rare decays into the pi+ pi- e+ e- final state are presented. A large CP-violating asymmetry A(K_L)=(13.9+-2.7+-2.0)% has been observed in the K_L to pi+ pi- e+ e- decay. The K_S to…
NA62 is a fixed target kaon experiment at the CERN SPS which aims at measuring the branching ratio of the $K^+\to\pi^+\nu\bar{\nu}$ decay with 10% precision. This ultra-rare kaon decay is theoretically extremely clean and an ideal place to…
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…
The Standard Model of particle physics currently provides our best description of fundamental particles and their interactions. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak…
$K\pi$ scattering and $K_{\mu 4}$ decays are studied at leading order of improved chiral perturbation theory. It is shown that high precision $K_{\mu 4}$ experiments at, e.g., DA$\Phi$NE should allow for a direct measurement of the quark…
The rare decays of the $K$ meson have had a long tradition as a laboratory for testing the symmetry properties of the weak interactions, and the manner in which these symmetries are broken by higher order effects. Present--day interest is…
The MEG collaboration searches for the mu to e gamma decay at the muon beam line PiE5 of the Paul Scherrer Institut in Switzerland. The world best upper limit has been set to be BR(mu to e gamma) < 5.7 10^-13 at 90% C.L. analyzing a data…
We demonstrate the potential of forthcoming mu -> e gamma and mu-e conversion experiments to implicate or disfavor solutions to the gauge hierarchy problem before the advent of the CERN Large Hadron Collider. Solutions of dynamical…
We discuss the advantages of combining the experimental bound on Br(B_s -> mu+ mu-) and the measured Br(B -> K l+l-) to get the model independent constraints on physics beyond the Standard Model. Since the two decays give complementary…
Rare decays of K mesons are reviewed from the perspective of testing the ``ones'' and ``zeros'' of the standard model. Decays K^+ -> pi^+ nu anti-nu and K_L -> pi^0 nu anti-nu probe the one-loop effective Hamiltonian for s -> d nu anti-nu,…
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…
Precise measurement of $\gamma$-rays following ordinary (non-radiative) capture of negative muons by natural Se, Kr, Cd and Sm, as well as isotopically enriched $^{48}$Ti, $^{76}$Se, $^{82}$Kr, $^{106}$Cd and $^{150}$Sm targets was…
We present recent measurements of $\tau$ physics at the Belle II experiment at SuperKEKB. Measurements include a test of $e-\mu$ lepton flavor universality in $\tau$ decays, a search for the lepton flavor violating $\tau \rightarrow \mu \mu…