Abstract
Using 6.32~fb$^{-1}$ of $e^+e^-$ collision data recorded by the BESIII detector at center-of-mass energies between $4.178$ to $4.226$~GeV, we present the first measurement of the decay $D_s^+\to f_0(980)e^+\nu_e,\,f_0(980)\to \pi^0\pi^0$. The product branching fraction of $D_s^+\to f_0(980)e^+\nu_e,\,f_0(980)\to \pi^0\pi^0$ is measured to be $(7.9\pm1.4_{\rm stat} \pm0.3_{\rm syst})\times 10^{-4}$, with a statistical significance of $7.8\sigma$. Furthermore, the upper limits on the product branching fractions of $D_s^+\to f_0(500)e^+\nu_e$ with $f_0(500)\to \pi^0\pi^0$ and the branching fraction of $D_s^+\to K_{S}^{0}K_{S}^{0}e^+\nu_e$ are set to be $6.4\times 10^{-4}$ and $3.9\times 10^{-4}$ at 90\% confidence level, respectively. Our results provide valuable inputs to the understanding of the structures of light scalar mesons.
Highlights
Monte Carlo (MC) Mπ0π0 (GeV/c2) MK0SK0S (GeV/c2)0.5 GeV=c2 in (a) is caused by the decay Dþs → K0Sð→ π0π0Þeþνe
Using 6.32 fb−1 of eþe− collision data recorded by the BESIII detector at center-of-mass energies between 4.178 to 4.226 GeV, we present the first measurement of the decay Dþs → f0ð980Þeþνe; f0ð980Þ → π0π0
We report the first search for the neutral channel Dþs → K0SK0Seþνe, associated with f0 → K0SK0S, avoiding heavy contamination from φ → KþK− decays
Summary
HAlso at State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, People’s Republic of China. The signal process eþe− → DÃsþD−s þ c:c: → γDþs D−s þ c:c: allows studying semileptonic Dþs decays with a tag technique [45,46] since the neutrino is the only one particle undetected. In the ST sample, a D−s meson is reconstructed through a particular hadronic decay without any requirement on the remaining measured charged tracks and EMC showers. The fit includes: The total four-momentum of reconstructed particles and the missing neutrino is constrained to the four-momentum of eþe− system; invariant masses of the two π0=K0S candidates, the D−s tag, the Dþs signal, and the γDÆs are constrained to the corresponding nominal masses [1]. The background is mostly caused by miscellaneous backgrounds with multiple photons
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