Combination of the top-quark mass measurements from the Tevatron collider

Abstract

The top quark is the heaviest known elementary particle, with a mass about 40 times larger than the mass of its isospin partner, the bottom quark. It decays almost 100% of the time to a W boson and a bottom quark. Using top-antitop pairs at the Tevatron proton-antiproton collider, the CDF and D0 Collaborations have measured the top quark's mass in different final states for integrated luminosities of up to 5.8 fb −1 . This paper reports on a combination of these measurements that results in a more precise value of the mass than any individual decay channel can provide. It describes the treatment of the systematic uncertainties and their correlations. The mass value determined is 173.18 ± 0.56 (stat) ± 0.75 (syst) GeV or 173.18 ± 0.94 GeV, which has a precision of ±0.54%, making this the most precise determination of the top-quark mass.

Strong Higgs interactions at a linear collider

“…The strong dependence on the top mass originates from the 1-loop correction to the ρ parameter, ∆ρ = ∆T ∝ m 2 t G F , which we have seen has an important impact on a. In this regard one must notice that the error reported in the current Tevatron average m t = (173.18 ± 0.94) GeV [84] does not include the theoretical uncertainty on the definition of the parameter extracted from the event kinematics in terms of the M S mass. If one instead adopts the larger error σ t = 2.8 GeV that follows from measuring the M S mass directly from the tt cross section [85], one finds that the uncertainty on a increases by a non-negligible amount [66].…”

Simultaneous measurement of forward-backward asymmetry and top polarization in dilepton final states fromtt¯production at the Tevatron

“…[39] for m t = 172.5 GeV. The generated top mass of 172.5 GeV differs from the Tevatron average mass of 173.18 ± 0.94 GeV [40]. We correct for this small difference in section VI B.…”

“…We obtain a measurement of (A tt , κP ) reported in Table VI for each dileptonic channel using the calibration coefficients from Table V and the raw measurements from Tables II and III. Two alpgen+pythia tt samples generated at different m t are used to estimate the dependence of the measurement on m t . Considering a top mass of m t = 173.18 ± 0.94 GeV [40] as reference, the dilepton results reported in Table VI …”

“…The uncertainty on the ISR model is defined as 50% of the difference between the nominal results and the results derived from a mc@nlo simulation in which the dependence of the forward-backward asymmetry on the p T of the tt system is removed. The uncertainty of 0.94 GeV on m t [40] is propagated to the final result using two alpgen+pythia samples generated with different m t values. We determine PDF uncertainties by varying the 20 parameters describing the CTEQ6M1 PDF [35] within their uncertainties.…”

Progress in the Determination of the Partonic Structure of the Proton

“…The vertical shaded band indicates the PDG world average value [112] of α S (M 2 Z ), while the horizontal shaded band in Figure 7(b) indicates the preliminary combination of ATLAS and CMS tt cross-section measurements [127,128]. The scale dependence, obtained by varying µ R and µ F by factors of two, subject to the constraint 1/2 ≤ µ R /µ F ≤ 2, leads to a theoretical uncertainty of +5.6 −4.9 %, while the top-mass dependence obtained by varying m t = 173.18 ± 0.94 GeV [122] leads to an uncertainty on the predicted cross section of ±2.8%, where these percentage uncertainties were obtained using the central MSTW08 PDF set.…”