相关论文: T-matrix of $Z^0$ Decay into Two Photons

We study the $Z\rightarrow \gamma \bar \gamma$ process in which the $Z$ boson decays into a photon $\gamma$ and a massless dark photon $\bar \gamma$, when the latter couples to standard-model fermions via dipole moments. This is a simple…

Z-boson decay $Z \rightarrow f\tilde{f}\gamma\gamma$ in the Standard Model is analysed. The distribution function on the invariant masses of the photon and fermion pairs is calculated in the leading logarithmic approximation. It is shown…

$Z \to \gamma \gamma$ decay amplitude is considered and proven to be zero due to properties of polarization vectors and Bose statistics. Triangular diagrams for a pseudoscalar $\to \gamma \gamma$ and $Z \to \gamma \gamma$ processes with…

We study the decay of a Z' - boson into U -unparticle and a photon. The extended Landau-Yang theorem is used. The clear photon signal would make the decay Z' \rightarrow \gamma U as an additional contribution mode for study of unparticle…

The one-loop contributions to the decays of the $CP$-odd and $CP$-even scalar bosons $A\to Z\gamma\gamma$ and $\phi\to Z\gamma\gamma$ ($\phi=h,H$) are calculated within the framework of $CP$-conserving THDMs, where they are induced by box…

We study the decay of the standard model Z boson into unparticle plus a single photon through a one-loop process. As in the anomaly type decay, only the axial-vector part of the Z coupling matching with the vector unparticle and/or the…

An analysis of the Higgs boson decay rates to $\gamma\gamma$ and $Z\gamma$ in the Inert Doublet Model is presented. We study the correlation between the two rates and perform extended analysis of the two-photon rate ($R_{\gamma\gamma}$). We…

The $Z\to \gamma \gamma$ and $Z\to gg$ decays are studied in the context of the renormalizable version of the Standard Model Extension. The $CPT$-odd $\bar{\psi}\gamma_5 \gamma^\mu b_\mu\psi$ bilinear interaction, which involves the…

The conservation of the vector current and the axial anomaly responsible for the $\pi_0 \to \gamma \gamma$ decay amplitude are obtained in leading order within the Taylor-Lagrange formulation of fields considered as operator-valued…

The scalar and vector meson exchange contributions to the doubly radiative decays $\eta^{(\prime)}\to\pi^0\gamma\gamma$ and $\eta^\prime\to\eta\gamma\gamma$ are analysed within the Linear Sigma Model and Vector Meson Dominance frameworks,…

The probability of the event that a neutrino produced in pion decay is detected in the intermediate $T$ shorter than the life-time $\tau_{\pi}$, $T \leq \tau_{\pi}$, is sensitive to the absolute mass of the neutrino. With a newly formulated…

In this paper, we present an improved calculation for the decay rate of the rare $Z$-boson decay into $J/\psi + J/\psi$. This decay is dominated by the photon fragmentation mechanism, i.e., the transition $Z\to J/\psi + \gamma^{*}$ followed…

We compute the decay rates for the processes $Z\to V+\gamma$, where $Z$ is the $Z$ boson, $\gamma$ is the photon, and $V$ is one of the vector quarkonia $J/\psi$ or $\Upsilon(nS)$, with $n=1$, $2$, or $3$. Our computations include…

Decay rates of the positronium molecule $\text{Ps}_{2}$ into two photons and into an electron-positron pair are determined. Previous studies find that these rates are very different, \[ \Gamma\left(\text{Ps}_{2}\to…

We study the correction to the radiative $\pi^0$ decay width due to finite light quark mass. Using lattice QCD with the overlap fermion formulation, we calculate the three-point function of the form $<PV_\mu V_\nu>$ in the (Euclidean)…

We study the mechanism of the weak decay process of Xi_b^0 into D^0 with a meson-baryon pair. It is shown that the dominant component of the prompt weak decay produces the meson-baryon pair with the spectator strange quark being transferred…

We search for the rare decay of the $D^{0}$ meson to two photons, $D^0 \rightarrow \gamma \gamma$, and present a measurement of the branching fraction for a $D^0$ meson decaying to two neutral pions, ${B}(D^0 \rightarrow \pi^0 \pi^0)$. The…

We describe a calculation of the two-photon decays of heavy vector-mesons, $B^*\to B\gamma\gamma$ and $D^*\to D\gamma\gamma$, by using the ``heavy meson chiral Lagrangian''. The decay amplitudes are expressed in terms of the strong coupling…

We calculate the neutral pion ($\pi^0$) to off-shell two photon ($\gamma^*\gamma^*$) transition form factor in lattice QCD. The transition form factor can be extracted from the three-point function of the form…

The study of the phenomenology of an extra neutral gauge boson, Z_H, can can help us to unravel the underlying theory. We study the decay of such a particle into two neutral gauge bosons, Z_H -> V_i Z (V_i=\gamma, Z), in two popular…