Top results from the Tevatron Page: 3 of 12
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Table 1: tt cross section measurements performed by the CDF and DO collaborations
in Run I (values are in pb).
experiment CDF DO
dilepton 8.4+: 6.4 3.3
topological 4.1 2.1
lepton tag 9.2 4.3 8.3 3.5
SVX tag 5.1 1.5
all-jets 7.6+. 7.1 3.2
combined 6.51.: 10 5.9 1.7 9
measured dilepton channel (W's - lv, l = e or ) accounts for 5% of all tt decays,
the lepton+jets channel (one W - lv, l = e or ), accounts for 30% of all tt decays.
In 44% of the decays both W's decay to jets. In the remaining 21% of decays one
or both W's decay to Tv. Since W - Tv - lviv 17, decays are indistinguishable
from W - lv, both experiments include such decays as part of the dilepton or
lepton+jets channels. Other channels are the lT dilepton channel (CDF, hadronic
decays of the T) and the ev channel (DO).
Tab.1 summarizes the ti cross section measurements for each of the decay
channels. Two different analyses were used in the lepton+jets channel. Top pair
production can be isolated by exploiting the topological characteristics of its final
state (used by DO) or by identifying a b-quark among the decay products. Both
experiments tag b-quarks from their semileptonic decay (muons for DO ; muons and
electrons for CDF). CDF also tags b-quarks based upon the presence in the event
of a secondary vertex from the decay of a long lived particle. Using all channels
combined, DO measures a cross section of 5.9 1.7 pb 9) and CDF 6.517 pb 10)
A re-analysis of the ej channel was also performed by DO . This analysis makes
use of advanced analysis techniques such a neural networks and leads to a 10%
improvement in acceptance and uncertainty for the channel in question.
Tab.2 summarizes all the measured values for the top quark mass. In the
Run I the single most precise measurement comes from the lepton+jets channel,
and the total combined relative uncertainty on the mass is < 3%. The mass of the
top affects Standard Model predictions via radiative corrections. These corrections
relate, for example, the mass of the top to the mass of the W and the Higgs bosons.
Thus, one of the goals of Run II is to achieve improved constraints on the mass of
the Higgs by performing precision measurements of the mass of the top and of the
W boson.
Run II of the Tevatron has begun as of March 2001. The upgraded detec-
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Barberis, E. Top results from the Tevatron, article, January 18, 2002; Batavia, Illinois. (https://digital.library.unt.edu/ark:/67531/metadc723689/m1/3/: accessed April 23, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.