Related papers: Radiative corrections in K --> pi l+ l- decays
We present a concise theoretical overview of radiative and rare B decays mediated by flavour-changing neutral-current transitions of the type b->s(d)gamma and b->s(d)l+l-.
The very clean theoretical predictions for the rare decays K --> pi nu nu_bar and KL --> pi0 l+ l- are reviewed, and their various theoretical inputs summarized. The less favorable situation for KL --> mu+ mu- is also commented.
A high statistics data sample of the decays of $K^+$ mesons to three charged particles was accumulated by the OKA experiment in 2012 and 2013. This allowed to select a clean sample of about 450 events with…
We discuss the complete virtual and soft-photonic O(alpha) corrections to AA -> W+W- within the electroweak Standard Model for arbitrary polarized photons. In the on-shell renormalization scheme for fixed M_W no leading corrections…
We compute the two-loop virtual corrections to the flavour changing neutral current process $b --> d l^+ l^-$. As calculation techniques integration by parts identities and the method of differential equations are used. The result is…
Recent measurements by the NA48 at CERN of selected $K_L$ decays are presented. These are the branching ratios and form factors for channels $K_L\to \pi^{\pm}\pi^0\e^{\mp}\nu_e$ (final result), $K_L\to\pi^{\pm}e^{\mp}\nu_e$ and $K_L\to…
We analyze $K_L$ lepton pair decays of $K_L \to l^+\l^-\gamma$ and $K_L \to l^+l^-l'^+l'^-$ $(l, l'=e, \mu)$ within the framework of the light-front QCD approach (LFQA). With the $K_L \to \gamma^* \gamma^*$ form factors evaluated in a model…
We report the recent results on rare kaon decays from the NA48/2 experiment. The precise measurement of direct photon emission (DE) in the decay K+- -> pi+- pi0 gamma and its interference (INT), with the INT amplitude being observed for the…
We compute O(alpha^3 ln alpha) corrections to the decay rates of para- and orthopositronium into two and three photons, respectively. For this calculation we employ the nonrelativistic QED regularized dimensionally and we explain how in…
We calculate all of the form factors for the one-photon, $K_L \rightarrow \pi^+ \pi^- \gamma^* \rightarrow \pi^+ \pi^- e^+e^-$ contribution to the $K_L \rightarrow \pi^+ \pi^- e^+e^-$ decay amplitude at leading order in chiral perturbation…
We discuss the decay tau^- -> nu_tau pi^- pi^0 gamma in terms of a model with the correct low-energy structure and with the relevant resonance degress of freedom. The nontrivial radiative dynamics becomes visible for large photon momenta…
We calculate the long-distance radiative corrections \delta^e_{LD} and \delta^{\mu}_{LD} to the K^0 -> \pi^- e^+ \nu_e and the K^0 -> pi^- \mu^+ \nu_{\mu} decay rates. This analysis includes contributions to the long-distance radiative…
For the low-energy anti-neutrino reaction, $\bar{\nu}_e + p \to e^+ + n$, which is of great current interest in connection with on-going high-precision neutrino-oscillation experiments, we calculate the differential cross section in a…
We derive an analytic expression for the O(alpha) radiative correction to the anti-nu_e (nu_e) spectrum in allowed beta-decay. The m -> 0 limit is convergent and leads to a very simple result (m is the electron mass). This is in sharp…
Flavour changing neutral current decays are a very sensitive test of the standard model and its extensions. In particular the decay K -> pi nu nubar constitutes a clean way to provide constraints, independent of long distance effects.…
We study the decay width, forward-backward asymmetry and the longitudinal lepton polarization for the exclusive decay B --> K^* l^+ l^- in the two Higgs doublet model with three level flavor changing neutral currents (model III) and analyse…
Rare radiative decays based on b->s+gamma transitions are among the most prominent examples of flavor-changing neutral current processes. They benefit from good theoretical control and experimental accessibility, large sensitivity to…
We determine the $\mathcal{O}(\alpha)$ correction to the energy spectrum of electrons produced in the decay of muons bound in atoms. We focus on the high-energy end of the spectrum that constitutes a background for the muon-electron…
The $K^+ \to \pi^0 \pi^0 e^+ \nu$ ($K_{e4}^{00}$) decay has been measured with stopped positive kaons for a data sample of 216 events. A comparison of the observed spectra with a Monte Carlo simulation determined the $K_{e4}^{00}$ form…
The result of lowest-order perturbation theory calculations of the photon and positron spectra in radiative pion(e2) decay are generalized to all orders of perturbation theory using the structure-function method. An additional source of…