Related papers: Helicity Amplitudes and Angular Decay Distribution…

We study the angular distribution of the charged lepton in the top-quark decay into a bottom quark and a W boson which subsequently decays into \ell\nu_{\ell}, when a hard gluon is radiated off. The absorptive part of the t \to bWg decay…

In this work, the massless-massive correspondence for the on-shell scattering amplitudes is constructed so the massive amplitudes could inherit advantageous techniques developed in the massless calculation. This correspondence is…

We study the decays into six quarks of off-shell pairs of W bosons produced in electron-positron annihilations, through the O(as^2) order in the strong coupling constant. We give explicit helicity amplitude formulae. We present numerical…

We present a detailed theoretical analysis of very rare, exclusive hadronic decays of the electroweak gauge bosons V=W, Z from first principles of QCD. Our main focus is on the radiative decays V->M+gamma, in which M is a pseudoscalar or…

We study the differential decay rate for the rare decay $\Lambda_b\to \Lambda(1520)(\to NK)\ell^+\ell^-$ where $\ell$ is a light lepton, as this decay mode can provide new and complementary constraints on the Wilson coefficients in $b\to…

Angular distribution of the final particles in the decay $\Lambda_c^+\to K^- \, \Delta (1232)^{++} \to K^- \, p \, \pi^+$ of the polarized charmed baryon is discussed. Asymmetries are proposed which allow for determination of the components…

An angular analysis and a measurement of the differential branching fraction of the decay $B^0_s\to\phi\mu^+\mu^-$ are presented, using data corresponding to an integrated luminosity of $3.0\, {\rm fb^{-1}}$ of $pp$ collisions recorded by…

Using (447.9 $\pm$ 2.3) million $\psi$(3686) events collected with the BESIII detector, the decays of $\chi_{cJ} \rightarrow \phi\phi$ ($J$=0, 1, 2) have been studied via the decay $\psi(3686)\rightarrow\gamma\chi_{cJ}$. The branching…

The angular distributions and the differential branching fraction of the decay B0 to K*(892)0 mu+ mu- are studied using a data sample corresponding to an integrated luminosity of 5.2 inverse femtobarns collected with the CMS detector at the…

The branching fractions and the decay amplitudes of B -> J/psi K^* decays are measured in a 29.4/fb data sample collected with the Belle detector at the KEKB electron-positron collider. The decay amplitudes of helicity states of the J/psi…

Angular distributions of $\phi$ meson decay amplitudes of $e^+e^-$ and $K^+K^-$ channels are computed using both specific interaction Lagrangians and simple arguments relying on angular momentum conservation. Based on the obtained results,…

The angular distributions of the rare decays $B^+ \to K^+\mu^+\mu^-$ and $B^0 \to K^0_{\rm\scriptscriptstyle S}\mu^+\mu^-$ are studied with data corresponding to 3$~$fb$^{-1}$ of integrated luminosity, collected in proton-proton collisions…

Knowledge of two-loop QCD amplitudes for processes $q\bar q \to V_1 V_2 \to (l_1\bar l'_1)(l_2 \bar l'_2)$ is important for improving the theoretical description of four-lepton production in hadron collisions. In this paper we compute these…

This paper describes the angular distribution of $\Lambda_b^0\to \Lambda(\to pK^-)\ell^+\ell^-$ decays. A full expression is given for the case of multiple interfering spin-states with spin $\leq \tfrac{5}{2}$. This distribution is relevant…

We illustrate the use of recursion relations in the computation of certain one-loop helicity amplitudes containing an arbitrary number of gauge bosons. After a brief review of the recursion relations themselves, we discuss the resolution of…

Recently proposed Feynman-diagram (FD) gauge propagator for massless and massive gauge bosons is obtained from a light-cone (LC) gauge propagator, by choosing the gauge vector along the opposite direction of the gauge boson three-momentum.…

We analyze the tauonic semileptonic baryon decays $\Lambda^0_b \to \Lambda^+_c + \tau^{-} +\bar \nu_{\tau}$ with particular emphasis on the lepton helicity flip contributions which vanish for zero lepton masses. We calculate the total rate,…

Rescattering effects of baryon and antibaryon in heavy quarkonium decays are investigated by studying their angular distributions. The rescattering amplitudes are phenomenologically evaluated by modeling the intermediate range interaction…

We discuss how the angular distribution of lepton pairs from decays of vector mesons depends on the choice of reference frame, and provide a geometrical description of the transformations of the coefficients of the angular distribution.…

We write down the four-dimensional fully differential decay distribution for the top quark decay $t \to Wb \to \ell \nu b$. We discuss how its eight physical parameters can be measured, either with a global fit or with the use of selected…