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

Includes the recent results summarized in the text

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Unformatted text preview: the recent results summarized in the text. From Alcaraz et al., 2009. Hobbs, Neubauer, and Willenbrock: Tests of the standard electroweak model at . . . R Ldt E‘ , cal T p‘ , trk T j‘ j ET 6 uT Yield Background W ! e fbÀ1 0:2 >30 GeV >18 GeV=c >30 GeV=c <15 GeV=c 63 964 7.5% CDF W !  D0 W ! e fbÀ1 fbÀ1 0:2 ÁÁÁ >30 GeV=c >30 GeV=c <15 GeV=c 51 128 1.1% Rev. Mod. Phys., Vol. 84, No. 4, October–December 2012 1:0 >25 GeV >10 GeV=c <1:05 >25 GeV=c <15 GeV=c 499 830 4.0% 1000 mW = (80349 ± 54) MeV 500 χ2/dof = 59 / 48 0 60 70 80 90 100 90 100 mT (GeV/c2) (b)W → eν 1500 1000 mW = (80493 ± 48) MeV 500 χ2/dof = 86 / 48 0 60 70 80 mT (GeV/c2) 10000 (c) D0, 1 fb-1 Data FAST MC Background χ2/dof = 48/49 7500 5000 2500 χ TABLE II. The integrated luminosity, kinematic selection, event yield, and backgrounds for the CDF and D0 W boson mass analyses. The background is given as a percentage of the total yield. (a)W →µν Events / 0.5 GeV/c2 transverse mass, mT  p‘ p ½1 À cosðފ in which  TT is the lepton-neutrino opening angle in the plane transverse to the beam. Although these variables are highly correlated, their systematic uncertainties are dominated by different sources, so the results are combined taking their statistical and systematic correlations into account. The event decay kinematics in the transverse plane are fully characterized by two quantities: (1) the lepton transverse ~T momentum p‘ and (2) the transverse momentum of the ~ hadronic recoil uT required to balance the transverse momentum of the W . The hadronic recoil is defined as the vector sum of all energy measured in the calorimeter excluding that deposited by the lepton. From these two measurements, the ~T ~ ~T neutrino transverse momentum is inferred: Àp ¼ p‘ þ uT . In practice, the recoil is computed using the event transverse missing energy (ET ) measured in the calorimeter after remov6 ing the contribution to calorimeter energy associated with the lepton. The W boson mass is determined by generating predicted distributions (templates) of the three measurement variables for a range of input W boson mass hypotheses. These are generated using dedicated fast Monte Carlo simulation programs, and the mass is determined by performing a binned maximum likelihood fit of these templates to the distributions observed in data. The Run II measurements use a blinding technique in which an unknown offset is added to the value returned from the fits until the analysis are finished. At that point, the offset is removed to reveal the true value. The results from the different fit variables (p‘ , p , mT ) and final T T states (e or ) are combined using the Best Linear Unbiased Estimate (BLUE) algorithm (Lyons, Gibaut, and Clifford, 1988; Valassi, 2003). Both D0 and CDF reported mass measurements using Run II data. The CDF result (Aaltonen et al., 2007a) uses R Ldt ¼ 0:2 fbÀ1 and results are reported for W ! e and...
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This document was uploaded on 09/28/2013.

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