Karim Trabelsi ; Vishal Bhardwaj

31 May 2018

Abstract: This figure shows the invariant mass distributions of charm candidates in 5 pb$^{-1}$ of collision data, in the mode $D^{*+}\to D^0 \pi^+$, $D^0 \to K^- \pi^+$. On the left is a 2-D plot of $\Delta M$ and $M(K\pi)$, on the upper right is $\Delta M$ for $1.845 < M(K\pi) < 1.885$ GeV/$c^2$ and on the lower right is $M(K\pi)$ for $0.144 < \Delta M < 0.146$ GeV/$c^2$. Events are required to contain at least three good tracks to purity the sample with processes of the type $e^+e^- \to $ hadrons, while rejecting beam induced background, Bhabha scattering, and other low multiplicity background sources. The charged kaon and pion tracks are required to have impact parameters, $|d_0|$ and $|z_0|$ less than 0.5 cm and 3.0 cm respectively. No particle identification criteria are applied. The $D^*$ candidates are required to have a centre-of-mass momentum of greater than 2.5 GeV/$c$ to select $c\bar c$ events. The internal document reference is BELLE2-NOTE-PH-2018-004.