Observation of $D \to a_{0}(980)π$ in the decays $D^{0} \rightarrow π^{+}π^{-}η$ and $D^{+} \rightarrow π^{+}π^{0}η$
hep-ex
/ Authors
BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, O. Afedulidis, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai
and 649 more authors
O. Bakina, I. Balossino, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Cetin, J. F. Chang, G. R. Che
/ Abstract
We report the first amplitude analysis of the decays $D^{0} \to π^{+} π^{-} η$ and $D^{+} \rightarrow π^{+}π^{0}η$ using a data sample taken with the BESIII detector at the center-of-mass energy of 3.773 GeV, corresponding to an integrated luminosity of 7.9 ${\rm fb}^{-1}$. The contribution from the process $D^{0(+)} \to a_{0}(980)^{+} π^{-(0)}$ is significantly larger than the $D^{0(+)} \to a_{0}(980)^{-(0)} π^{+}$ contribution. The ratios $\mathcal{B}(D^{0} \rightarrow a_{0}(980)^{+}π^{-})/\mathcal{B}(D^{0} \rightarrow a_{0}(980)^{-}π^{+})$ and $\mathcal{B}(D^{+} \rightarrow a_{0}(980)^{+}π^{0})/\mathcal{B}(D^{+} \rightarrow a_{0}(980)^{0}π^{+})$ are measured to be $7.5^{+2.5}_{-0.8\,\mathrm{stat.}}\pm1.7_{\mathrm{syst.}}$ and $2.6\pm0.6_{\mathrm{stat.}}\pm0.3_{\mathrm{syst.}}$, respectively. The measured $D^{0}$ ratio disagrees with the theoretical predictions by orders of magnitudes, thus implying a substantial contribution from final-state interactions.