$\Delta m_D$ and $\Delta \Gamma_D$ revisted

Abstract

The lifetime difference ($y_D=\Delta\Gamma_D/2\Gamma_D$) and mass difference ($x_D=\Delta m_D/\Gamma_D$) of neutral $D$ meson have been measured with $y_D=(0.80\pm 0.13)%$ and $x_D=(0.59 \pm 0.20)%$, respectively. Intriguingly, in contrast with the cases of $K$ and $B_q$ systems, the current data indicate that $y_D/x_D \sim 1$ and $y_D$ favors to be larger than $x_D$. For explaining the experimental indication, we here study the $D-\bar D$ oscillation in the framework of unparticle physics. We demonstrate that {\it the peculiar phase appearing in off-shell unparticle propagator} could play an important role on $x_D$ and $y_D$.