Impact of colored scalars on $D^0-\bar D^0$ mixing in diquark models

Understand

Inspired by the recent observation of the $D^0-\bar D^0$ mixing, we explore the effects of colored scalars on the $\Delta C=2$ process in diquark models.

• As an illustration, we investigate the diquarks with the quantum numbers of (6, 1, 1/3) and (6, 1, 4/3) under $SU(3)_C\times SU(2)_L\times U(1)_Y$ gauge symmetries, which contribute to the process at one-loop and tree levels, respectively.
• We show that $\Delta m_D$ gives the strongest constraint on the free parameters.
• In addition, we find that the small couplings can be naturally interpreted by the suppressed flavor mixings if the diquark of (6, 1, 4/3) only couples to the third generation.