Using a sample of $(10087 \pm 44)\times10^{6}$ $J/\psi$ events collected with the BESIII detector, an improved measurement of the decay $\eta'\to e^+e^-\omega$, with $\omega\to\pi^+\pi^-\pi^0$ and $\pi^0\to\gamma\gamma$, is performed. The branching fraction is determined to be $$\mathcal{B}(\eta'\to e^+e^-\omega)=(1.79 \pm 0.09\,(\mathrm{stat}) \pm 0.12\,(\mathrm{syst}))\times10^{-4},$$ where the first uncertainty is statistical and the second is systematic. This result is consistent with the previous measurement and is obtained with significantly improved precision. Furthermore, the first measurement of the transition form-factor cutoff parameter for this decay is reported, $$\Lambda^{-1}=(2.92 \pm 0.83\,(\mathrm{stat}) \pm 0.15\,(\mathrm{syst}))~\mathrm{GeV}^{-1}.$$ These measurements provide valuable input for understanding the internal structure of the $\eta'$ meson and for testing theoretical models.
Improved measurement of 𝜂′→𝑒+𝑒−𝜔
Di Fiore, E.;Garzia, I.;Melendi, F. M.;
2026
Abstract
Using a sample of $(10087 \pm 44)\times10^{6}$ $J/\psi$ events collected with the BESIII detector, an improved measurement of the decay $\eta'\to e^+e^-\omega$, with $\omega\to\pi^+\pi^-\pi^0$ and $\pi^0\to\gamma\gamma$, is performed. The branching fraction is determined to be $$\mathcal{B}(\eta'\to e^+e^-\omega)=(1.79 \pm 0.09\,(\mathrm{stat}) \pm 0.12\,(\mathrm{syst}))\times10^{-4},$$ where the first uncertainty is statistical and the second is systematic. This result is consistent with the previous measurement and is obtained with significantly improved precision. Furthermore, the first measurement of the transition form-factor cutoff parameter for this decay is reported, $$\Lambda^{-1}=(2.92 \pm 0.83\,(\mathrm{stat}) \pm 0.15\,(\mathrm{syst}))~\mathrm{GeV}^{-1}.$$ These measurements provide valuable input for understanding the internal structure of the $\eta'$ meson and for testing theoretical models.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
