Observation of an Altered $a_0(980)$ Line shape in $D^{+}\to {\pi }^{+}\eta \eta$

BESIII Collaboration, M. Ablikim, M. N. Achasov +693

Using $20.3{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collision data collected with the BESIII detector at $\sqrt{s}=3.773\mathrm{GeV}$, we perform the first amplitude analysis of the decay $D^+\to…