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

In table iii the systematic uncertainties are

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Unformatted text preview: ic uncertainties are dominated by the lepton energy calibration. This contributes 17 MeV uncertainty to the CDF p‘ and p channels, 30 MeV to the CDF mT channel, and T T 34 MeV to each D0 channel. These results are shown along with previous measurements in Fig. 5. The world average combination (Alcaraz et al., 2009; Tevatron Electroweak Working Group, 2009b) has been updated with these measurements using the BLUE (Lyons, Gibaut, and Clifford, 1988; Valassi, 2003) algorithm including correlations. The result is MW ¼ 80:420 Æ 0:031 GeV=c2 : Because the systematic uncertainties are dominated by the statistical precision of the calibrations determined from control data samples, the systematic uncertainty in future measurements is expected to improve as the integrated luminosity increases. The ultimate limiting systematic is expected to be that introduced by the parton distribution functions. In the TABLE III. The individual CDF and D0 W boson mass results and their combinations. When two uncertainties are given, the first is the statistical uncertainty and the second is the systematic uncertainty. MW (MeV) CDF W ! e Combined CDF W !  Combined CDF W ! e þ  D0 W ! e D0 combined mT pe T ET 6 mT p T ET 6 mT pe T ET 6 2 =dof 80 493 Æ 48 Æ 39 80 451 Æ 58 Æ 45 80 473 Æ 57 Æ 54 80 477 Æ 62 80 349 Æ 54 Æ 27 80 321 Æ 66 Æ 40 80 396 Æ 66 Æ 46 80 352 Æ 60 80 413 Æ 34 Æ 34 80 401 Æ 23 Æ 37 80 400 Æ 27 Æ 40 80 402 Æ 23 Æ 43 80 401 Æ 21 Æ 38 86=48 63=62 63=62 Rev. Mod. Phys., Vol. 84, No. 4, October–December 2012 59=48 72=62 44=63 48=49 39=31 32=31 1483 CDF Run 0/I 80.436 ± 0.081 [24] D0 Run I 80.478 ± 0.083 [25] CDF Run II 80.413 ± 0.048 [28] D0 Run II 80.402 ± 0.043 [29] Tevatron 2009 80.420 ± 0.031 [30] LEP2 average 80.376 ± 0.033 [20-23] World average 80.399 ± 0.023 [30] July 09 80 80.2 80.4 80.6 mW (GeV/c2 ) FIG. 5 (color online). Ideogram of previous measurements, the Run-II CDF and D0 measurements and the new world average. The reference is shown to the right of each measurement. current results, this contributes an uncertainty of 11 MeV to all channels with a 100% correlation among the channels. C. W Width Like the W boson mass, the width ÀW is also predicted by the SM. It is given by    3 GF M W pffiffiffi ð1 þ Þ (4) ÀW ¼ 3 þ 2NC 1 þ S  6 2 in which NC ¼ 3 is the number of colors, 1 þ S = is the QCD correction factor to first order, and  ¼ 2:1% (Rosner, Worah, and Takeuchi, 1994) is an EW correction factor. Direct measurements of ÀW were made by CDF (Affolder et al., 2000) and D0 (Abazov et al., 2002b) using Tevatron Run I data and combined (Abazov et al., 2002b). Measurements were also made by the experiments at LEP (Abbiendi et al., 2006a; Achard et al., 2006; Schael et al., 2006; Abdallah et al., 2008). Because the W boson mass is distributed according to a Breit-Wigner formula, there is a tail at large mass values. The W boson width result is obtained using the mT distribution in a r...
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