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Register a new userCombination of CDF and D0 W-Boson Mass Measurements
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We summarize and combine direct measurements of the mass of the $W$ boson in $sqrt{s} = 1.96 text{TeV}$ proton-antiproton collision data collected by CDF and D0 experiments at the Fermilab Tevatron Collider. Earlier measurements from CDF and D0 are combined with the two latest, more precise measurements: a CDF measurement in the electron and muon channels using data corresponding to $2.2 mathrm{fb}^{-1}$ of integrated luminosity, and a D0 measurement in the electron channel using data corresponding to $4.3 mathrm{fb}^{-1}$ of integrated luminosity. The resulting Tevatron average for the mass of the $W$ boson is $MW = 80,387 pm 16 text{MeV}$. Including measurements obtained in electron-positron collisions at LEP yields the most precise value of $MW = 80,385 pm 15 text{MeV}$.
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We report the combination of recent measurements of the helicity of the W boson from top quark decay by the CDF and D0 collaborations, based on data samples corresponding to integrated luminosities of 2.7 - 5.4 fb^-1 of ppbar collisions collected during Run II of the Fermilab Tevatron Collider. Combining measurements that simultaneously determine the fractions of W bosons with longitudinal (f0) and right-handed (f+) helicities, we find f0 = 0.722 pm 0.081 [pm 0.062 (stat.) pm 0.052 (syst.)] and f+ = -0.033 pm 0.046 [pm 0.034 (stat.) pm 0.031 (syst.)]. Combining measurements where one of the helicity fractions is fixed to the value expected in the standard model, we find f0 = 0.682 pm 0.057 [pm 0.035 (stat.) pm 0.046 (syst.)] and f+ = -0.015pm0.035 [pm 0.018 (stat.) pm 0.030 (syst.)]. The results are consistent with standard model expectations.
The Standard Model of electroweak interactions has had great success in describing the observed data over the last three decades. The precision of experimental measurements affords tests of the Standard Model at the quantum loop level beyond leading order. Despite this great success it is important to continue confronting experimental measurements with the Standard Model predictions as any deviation would signal new physics. As a fundamental parameter of the Standard Model, the mass of the W-boson, M_W, is of particular importance. Aside from being an important test of the SM itself, a precision measurement of M_W can be used to constrain the mass of the Higgs boson, M_H. In this article we review the principal experimental techniques for determining M_W and discuss their combination into a single precision M_W measurement, which is then used to yield constraints on M_H. We conclude by briefly discussing future prospects for precision measurements of the W-boson mass.
We summarize the current top quark mass ($m_t$) measurements from the CDF and D0 experiments at Fermilab. We combine published results from Run I (1992--1996) with the most precise published and preliminary Run II (2001--2011) measurements based on $pbar{p}$ data corresponding to up to $9.7:{rm fb}^{-1}$ of $pbar{p}$ collisions. Taking correlations of uncertainties into account, and combining the statistical and systematic contributions in quadrature, the preliminary Tevatron average mass value for the top quark is $m_t = 174.30 pm 0.65:mathrm{GeV}/c^{2}$, corresponding to a relative precision of $0.37%$
We combine the results of the CDF and D0 searches for chargino and neutralino production in Gauge-Mediated SUSY using the two-photon and missing Et channel. The data are p-pbar collisions produced at the Tevatron with sqrt(s)=1.96 TeV, with 202 pb^-1 collected at CDF and 263 pb^-1 collected at D0. The combined limit excludes a chargino mass less than 209 GeV/c^2. This result significantly extends the individual experimental limits.
The $W$ boson mass is measured using proton-proton collision data at $sqrt{s}=13$ TeV corresponding to an integrated luminosity of 1.7 fb$^{-1}$ recorded during 2016 by the LHCb experiment. With a simultaneous fit of the muon $q/p_T$ distribution of a sample of $W to mu u$ decays and the $phi^*$ distribution of a sample of $Ztomumu$ decays the $W$ boson mass is determined to be begin{equation*} m_{W} = 80354 pm 23_{rm stat} pm 10_{rm exp} pm 17_{rm theory} pm 9_{rm PDF}~mathrm{MeV}, end{equation*} where uncertainties correspond to contributions from statistical, experimental systematic, theoretical and parton distribution function sources. This is an average of results based on three recent global parton distribution function sets. The measurement agrees well with the prediction of the global electroweak fit and with previous measurements.
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