Evidence for the Direct Two-Photon Transition from $\psi (3686)$ to $J/\psi$

Abstract

The two-photon transition $\psi (3686)\to \gamma \gamma J/\psi$ is studied in a sample of 106 million $\psi (3686)$ decays collected by the BESIII detector. The branching fraction is measured to be $(3.1\pm0.6(\unit{stat})^{+0.8}_{-1.0}(\unit{syst})) \times10^{-4}$ using $J/\psi \to e^{+}{e}^{-}$ and $J/\psi \to {\mu }^{+}{\mu }^{-}$ decays, and its upper limit is estimated to be $4.5\times 10^{-4}$ at the 90% conference level. This work represents the first measurement of a two-photon transition among charmonium states. The orientation of the $\psi (3686)$ decay plane and the $J/\psi$ polarization in this decay are also studied. In addition, the product branching fractions of sequential $E1$ transitions $\psi (3686)\to \gamma {\chi }_{cJ},{\chi }_{cJ}\to \gamma J/\psi (J=0,1,2)$ are reported.

6 pages, 3 figures, 2 tables

References in corpus (15)

• Heavy quarkonium: progress, puzzles, and opportunities
• Design and Construction of the BESIII Detector
• Coherent Exclusive Exponentiation For Precision Monte Carlo Calculations
• Higher Charmonia and X,Y,Z states with Screened Potential
• Charmonium levels near threshold and the narrow state $X(3872) \to π^{+}π^{-}\jpsi$
• Branching fraction measurements of χ_{c0} and χ_{c2} to π^0π^0 and ηη
• Hadroproduction of J/psi and Upsilon in association with a heavy-quark pair
• Measurements of h_c(^1P_1) in psi' Decays
• The hidden charm decay of Y(4140) by the rescattering mechanism
• Branching Fractions for Transitions of psi(2S) to J/psi
• Branching Fractions for psi(2S) to J/psi Transitions
• ψ(2S) Decays into $\J$ plus Two Photons
• Precise measurement of spin-averaged chi_{cJ}(1P) mass using photon conversions in psi(2S) -> gamma chi_{cJ}
• The discrete contribution to ${\psi }^{\prime }\to J/\psi +\gamma \gamma$
• Update on Charmonium Theory

Cited by in corpus (5)

• Observation of a charged charmoniumlike structure in $e^{+}{e}^{-}\to (D^{\ast }{\bar{D}}^{\ast }{)}^{\pm }{\pi }^{\mp }$ at $\sqrt{s}=4.26$GeV
• Measurement of higher-order multipole amplitudes in $\psi (3686)\to \gamma {\chi }_{c1,2}$ with ${\chi }_{c1,2}\to \gamma J/\psi$ and search for the transition ${\eta }_c(2S)\to \gamma J/\psi$
• Precision measurements of branching fractions for ${\psi }^{\prime }\to {\pi }^{0}J\psi$ and $\eta J\psi$
• Branching fraction measurements of $\psi (3686)\to \gamma {\chi }_{cJ}$
• Radiative transitions among the vector and scalar heavy quarkonium states with covariant light-front quark model