Estimates of $m_d - m_u$ and $\langle\bar{d}d\rangle - \langle\bar{u}u\rangle$ 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: $m_d -m_u =3\pm 1\, MeV$, $\langle\bar{d}d\rangle -\langle\bar{u}u\rangle = -(2.5\pm 1)\cdot 10^{-3}\langle\bar{u}u\rangle$ (at a standard normalization point, $\mu = 0.5\, GeV$).