Speaker
Description
The decay $D^{0} \rightarrow \pi^{+}\pi^{-}\pi^{+}\pi^{-}$, with $D^{0} \rightarrow a_1(1260)^{+} \pi^{-}$ being the dominant intermediate state, provides an excellent environment to study the properties of the $a_1(1260)$ meson. We present new measurements of the $a_1(1260)$’s mass and width using data collected with the CLEO-c detector. The $a_1(1260)$ contribution is disentangled from the other occurring decay channels by means of a full five-dimensional amplitude analysis. A state-of-the-art parameterization of the $a_1(1260)$ lineshape is used taking into account the resonant three-pion substructure. In addition, several other lineshape models are tested. As we observe a significant dependence of the measured width on the chosen parameterization, a quasi-model-independent study of the lineshape is performed as well.
