Estimates of $m_d-m_u$ and $⟨\bar{d}d⟩-⟨\bar{u}u⟩$ from QCD sum rules for $D$ and $D^{\ast }$ isospin mass differences

Abstract

The recent experimental data on $D^{+}-D^0$ and $D^{\ast +}-D^{\ast 0}$ mass differences are used as inputs in the QCD sum rules to obtain new estimates on the mass difference of light quarks and on the difference of their condensates: $m_d-m_u=3\pm 1MeV$, $⟨\bar{d}d⟩-⟨\bar{u}u⟩=-(2.5\pm 1)\cdot 10^{-3}⟨\bar{u}u⟩$ (at a standard normalization point, $\mu =0.5GeV$).

Comments: 6 pages, TPI-MINN-92/69-T and BUTP-93/2