Combination of CDF and D0 results on the mass of the top quark using up to 9.7 fb${}^{-1}$ at the Tevatron

We summarize the current top-quark mass measurements from the CDF and D0 experiments at Fermilab. We combine published Run I (1992–1996) results with the most precise published and preliminary Run II (2001–2011) measurements based on data corresponding to up to 9.7 fb${}^{-1}$ of $p\bar{p}$ collisions. Taking correlations of uncertainties into account, and combining the statistical and systematic uncertainties, the resulting preliminary Tevatron average mass of the top quark is $M_{top}=174.34\pm 0.64GeV\mathrm{/}{c}^2$, corresponding to a relative precision of 0.37%.