Article

# Measurement of the W Boson Mass with the D0 Detector

Joint Institute for Nuclear Research, Dubna, Russia.

Physical Review Letters (Impact Factor: 7.51). 04/2012; 108(15):151804. DOI: 10.1103/PhysRevD.89.012005 Source: PubMed

**ABSTRACT**

We give a detailed description of the measurement of the W boson mass, MW, performed on an integrated luminosity of 4.3 fb-1, which is based on similar techniques as used for our previous measurement done on an independent data set of 1 fb-1 of data. The data were collected using the D0 detector at the Fermilab Tevatron Collider. This data set yields 1.68×106 W→eν candidate events. We measure the mass using the transverse mass, electron transverse momentum, and missing transverse energy distributions. The MW measurements using the transverse mass and the electron transverse momentum distributions are the most precise of these three and are combined to give MW=80.367±0. 013(stat)±0.022(syst) GeV=80.367±0.026 GeV. When combined with our earlier measurement on 1 fb-1 of data, we obtain MW=80.375±0.023 GeV.

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**ABSTRACT:**The latest measurements of the mass of the W boson, one of two elementary particles that mediate the weak nuclear force, are a powerful reminder of the profound beauty in the standard model of particle physics. - [Show abstract] [Hide abstract]

**ABSTRACT:**Isolated lepton momenta, in particular their directions are the most precisely measured quantities in pp collisions at LHC. This offers opportunities for multitude of precision measurements. It is of practical importance to verify if precision measurements with leptons in the final state require all theoretical effects evaluated simultaneously or if QED bremsstrahlung in the final state can be separated without unwanted precision loss. Results for final-state bremsstrahlung in the decays of narrow resonances are obtained from the Feynman rules of QED in an unambiguous way and can be controlled with a very high precision. Also for resonances of non-negligible width, if calculations are appropriately performed, such separation from the remaining electroweak effects can be expected. Our paper is devoted to validation that final-state QED bremsstrahlung can indeed be separated from the rest of QCD and electroweak effects, in the production and decay of Z and W bosons, and to estimation of the resulting systematic error. The quantitative discussion is based on Monte Carlo programs PHOTOS and SANC, as well as on KKMC which is used for benchmark results. We show that for a large class of W and Z boson observables as used at LHC, the theoretical error on photonic bremsstrahlung is 0.1 or 0.2 %, depending on the program options used. An overall theoretical error on the QED final-state radiation, i.e. taking into account missing corrections due to pair emission and interference with initial state radiation is estimated respectively at 0.2 % or 0.3 % again depending on the program option used. - [Show abstract] [Hide abstract]

**ABSTRACT:**The W mass is a crucial parameter in the Standard Model (SM) of particle physics, providing constraints on the mass of the Higgs boson as well as on new physics models via quantum loop corrections. On the other hand, any deviation of the triple gauge boson couplings (TGC) from their values predicted by the SM would be also an indication for new physics. We present recent measurements on W boson mass and searches for anomalous TGC (aTGC) in Wγ, Zγ, WW, WZ and ZZ at Fermilab Tevatron both by CDF and DØ Collaborations. The CDF Collaboration has measured the W boson mass using data corresponding to 2.2 fb-1 of integrated luminosity. The measurement, performed using electron and muon decays of W boson, yields a mass of MW = 80387 ± 19 MeV. The DØ Collaboration has measured MW = 80367 ± 26 MeV with data corresponding to 4.3 fb-1 of integrated luminosity in the channel W → ev. The combination with an earlier DØ result, using independant data sample at 1 fb-1 of integrated luminosity, yields MW = 80375 ± 23 MeV. The limits on anomalous TGCs parameters are consistent with the SM expectations.

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