A measurement of the ratio of inclusive cross sections σ(ppˉ→Z+b jet)/σ(ppˉ→Z+jet)\sigma(p\bar{p}\rightarrow Z+b{\rm\, jet})/ \sigma(p\bar{p}\rightarrow Z+{\rm jet}) at s=1.96\sqrt{s}=1.96 TeV

The ratio of the cross section for $p\bar{p}$ interactions producing a $Z$ boson and at least one $b$ quark jet to the inclusive $Z+{\rm jet}$ cross section is measured using $4.2\ {\rm fb}^{-1}$ of $p\bar{p}$ collisions collected with the \dzero\ detector at the Fermilab Tevatron collider at $\sqrt{s}=1.96$ TeV. The $Z\rightarrow\ell^+\ell^-$ candidate events with at least one $b$ jet are discriminated from $Z+$ charm and light jet(s) events by a novel technique that exploits the properties of the tracks associated to the jet. The measured ratio is $0.0193\pm0.0027$ for events having a jet with transverse momentum \pt > 20 \GeV and pseudorapidity $|\eta| \leq 2.5$, which is the most precise to date and is consistent with theoretical predictions.Comment: Submitted to Phys. Rev. Let

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

18 pages, 4 figuresWe summarize the current top-quark mass measurements from the CDF and DO 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 $M_{top} = 174.34 \pm 0.64 ~GeV/c^2$, corresponding to a relative precision of 0.37%