Up-down Asymmetries and Angular Distributions in $D\to K_1(\to K\pi \pi ){\ell }^{+}{\nu }_{\ell }$

Lingzhu Bian, Liang Sun, Wei Wang

Using the helicity amplitude technique, we derive differential decay widths and angular distributions for the decay cascade $D\to K_{1}(1270,1400)\ell^+ν_{\ell}\to (Kππ)\ell^+ν_{\e…