RevModPhys.84.1477】Tests of the standard electroweak model at the energy frontier

Top gevc fig 43 color online contours of constant logl

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Unformatted text preview: t can be used as a probability density. The event probability is then used either as input to additional likelihoods or the joint likelihood for the entire sample is formed as the product of the event probabilities and minimized as a function of Mt . The methods used in early Run II top mass measurements had systematic uncertainty from the energy calibration of reconstructed jets which, if unmodified, would have quickly surpassed the statistical uncertainty. A method was developed to incorporate an in situ calibration scale factor as a second fit parameter when determining the top mass. As an example, the ME method event probability definition was modified to the form now in general use. This form is Pðx; Mt ;kjes Þ¼ AðxÞ½fPtt"ðx; Mt ;kjes Þþð1 À fÞPbkg ðx; kjes ފ in which kjes is a scale factor applied to all jet energies. In this form the transfer functions also become dependent on the calibration W ðy; x; kjes Þ. The negative log likelihood minimized to determine the top mass thus becomes a function of two variables, mtop and kjets , both of which are varied during the minimization. As an example, Fig. 43 shows the 2D contour in the Ájes  kjes À 1 versus mtop plane from the Mt measurement using the ‘‘ and ‘ þ jets nal states simultaneously (Aaltonen et al., 2009d). R TABLE XXIII. Summary of published Run II top-quark mass measurements. Additional preliminary results using up to Ldt ¼ 4 fbÀ1 have been reported by both CDF and D0. The Particle Data Group average includes only some of these results, and the Tevatron average is based on a subset of the results in this table and additional preliminary results. R Ldt Analysis Mt Main Uncertainty Value Expt. Channel ðfbÀ1 Þ method (GeV=c2 ) systematic source (GeV=c2 ) Ref. ‘‘ þ ð‘ þ jetsÞ ‘‘ ‘ þ jets All jets ET þ jets 6 Tevatron (incl. prel.) 1.9 2.9 2 1.2 1 1 1.9 1 0.7 0.4 0.3 1 1.0 0.3 171:9 Æ 1:7ðstat þ JESÞ Æ 1:1ðsystÞ  WT 165:5þ3::4 ðstatÞ Æ 3:1ðsystÞ Jet calibration À3 3 Matrix 171:2 Æ 2:7ðstatÞ Æ 2:9ðsystÞ Jet calibration Template þ Mt 170:74:2 :9 ðstatÞ Æ 2:6ðsystÞ Æ 2:4ðtheoÞ Jet calibration À3 Matrix 164:5 Æ 3:9ðstatÞ Æ 3:9ðsystÞ Jet calibration Matrix þ WT 174:7 Æ 4:4ðstatÞ Æ 2:0ðsystÞ Jet calibration Matrix 172:7 Æ 1:8ðstatÞ Æ 1:2ðsystÞ Generator, jet calib. Matrix 171:5 Æ 1:8ðstat þ JESÞ Æ 1:1ðsystÞ b=u, d,s, frag. Decay length 180:7þ15::5 ðstatÞ Æ 8:6ðsystÞ Bkg. shape À13 4 Ideogram 173:7 Æ 4:4ðstat þ JESÞ Æ 2:1ðsystÞ b=u; d; s calib. þ3 7 Template þ DLL 173:5À3::6 ðstat þ JESÞ Æ 1:3ðsystÞ Signal model Line shape 174:0 Æ 2:2ðstatÞ Æ 4:8ðsystÞ Jet calibration Matrix 171:1 Æ 3:7ðstat þ JESÞ Æ 2:1ðsystÞ Parton shower, jet calib. : Spectra 172:310986 ðstatÞ Æ 10:8ðsystÞ Jet calibration À: 173:1 Æ 0:6ðstatÞ Æ 1:1ðsystÞ PDGp 171:2 Æ 2:1 Particle Data Group 2008 a b c d e f Aaltonen et al., 2009d. Aaltonen et al., 2008c. g Aaltonen et al....
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This document was uploaded on 09/28/2013.

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