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Register a new userMeasurement of the W boson helicity in top quark decays using 5.4 fb^-1 of ppbar collision data
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We present a measurement of the helicity of the W boson produced in top quark decays using ttbar decays in the l+jets and dilepton final states selected from a sample of 5.4 fb^-1 of collisions recorded using the D0 detector at the Fermilab Tevatron ppbar collider. We measure the fractions of longitudinal and right-handed W bosons to be f_0 = 0.669 +- 0.102 [ +- 0.078 (stat.) +- 0.065 (syst.)] and f_+ = 0.023 +- 0.053 [+- 0.041 (stat.) +- 0.034 (syst.)], respectively. This result is consistent at the 98% level with the standard model. A measurement with f_0 fixed to the value from the standard model yields f_+ = 0.010 +- 0.037 [+- 0.022 (stat.) +- 0.030 (syst.) ].
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We present measurements of the tWb coupling form factors using information from electroweak single top quark production and from the helicity of W bosons from top quark decays in ttbar events. We set upper limits on anomalous tWb coupling form factors using data collected with the D0 detector at the Tevatron ppbar collider corresponding to an integrated luminosity of 5.4 fb^-1.
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.
We report the first measurement of the top quark mass using the decay length technique in ppbar collisions at a center-of-mass energy of 1.96 TeV. This technique uses the measured flight distance of the b hadron to infer the mass of the top quark in lepton plus jets events with missing transverse energy. It relies solely on tracking and avoids the jet energy scale uncertainty that is common to all other methods used so far. We apply our novel method to a 695 pb^-1 data sample recorded by the CDF II detector at Fermilab and extract a measurement of m_t = 180.7^{+15.5}_{-13.4} (stat.) pm 8.6 (syst.) GeV/c^2. While the uncertainty of this result is larger than that of other measurements, the dominant uncertainties in the decay length technique are uncorrelated with those in other methods. This result can help reduce the overall uncertainty when combined with other existing measurements of the top quark mass.
We report measurements related to hadronic $B$ decays to final states that contain charm mesons. The analyses are performed on a $62.8~mathrm{fb}^{-1}$ data set collected by the Belle II experiment at a center-of-mass energy corresponding to the mass of the $Upsilon(4S)$ resonance. The measurements reported are for the decay modes $B^-to D^0 h^-$, $B^{-}to D^{*0}h^-$, $bar{B}^{0}to D^{+} h^{-}$ and $bar{B}^{0}to D^{*+} h^{-}$, where $h=pi$ or $K$. These modes are either signal or control channels for measurements related to the unitarity triangle angle $gamma$ in direct or time-dependent $CP$-violation measurements. The reported observables are the ratios between the $Bto D^{(*)}K$ and $Bto D^{(*)}pi$ decay rates, which are found to be in agreement with previous measurements.
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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