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Combination of the top-quark mass measurements from the Tevatron collider
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2012 Update of the Combination of CDF and D0 Results for the Mass of the W Boson
Get PDFWe summarize and combine the results on the direct measurements of the mass of the W boson in data collected by the Tevatron experiments CDF and D0 at Fermilab. Earlier results from CDF Run-0 (1988-1989), D0 and CDF Run-I (1992-1995) and D0 results from 1 fb{sup -1} (2002-2006) of Run-II data are now combined with two new, high statistics Run-II measurements: a CDF measurement in both electron and muon channels using 2.2 fb{sup -1} of integrated luminosity collected between 2002 and 2007, and a D0 measurement in the electron channel using 4.3 fb{sup -1} collected between 2006 and 2009. As in previous combinations, the results are corrected for inconsistencies in parton distribution functions and assumptions about electroweak parameters used in the different analyses. The resulting Tevatron average for the mass of the W boson is M{sub W} = 80,387 {+-} 16 MeV and a new world average including data from LEP II is M{sub W} = 80,385 {+-} 15 MeV
Measurement of W±Z production in proton-proton collisions at √s=7 TeV with the ATLAS detector
Get PDFA study of W ± Z production in proton-proton collisions at √s=7 TeV is presented using data corresponding to an integrated luminosity of 4.6 fb−1 collected with the ATLAS detector at the Large Hadron Collider in 2011. In total, 317 candidates, with a background expectation of 68±10 events, are observed in double-leptonic decay final states with electrons, muons and missing transverse momentum. The total cross-section is determined to be σtotWZ=19.0+1.4−1.3(stat.)±0.9(syst.)±0.4(lumi.) pb , consistent with the Standard Model expectation of 17.6+1.1−1.0 pb . Limits on anomalous triple gauge boson couplings are derived using the transverse momentum spectrum of Z bosons in the selected events. The cross-section is also presented as a function of Z boson transverse momentum and diboson invariant mass
Meson distribution amplitudes: applications to weak radiative B decays and в transition form factors
Get PDFThis thesis examines the applications and determinations of meson light-cone distribution amplitudes, which enter the theoretical description of exclusive processes at large moment urn transfer. The investigation of such processes, in the context of в physics, provides one with a rich and extensive way of determining the Standard Model parameters of the CKM matrix, which are essential in describing CP violation, and searching for tell-tale signs of new physics beyond the Standard Model. We investigate the twist-2 and twist-3 distribution amplitudes of vector mesons and fully examine SU(3)(_F)-breaking effects and include leading G-parity violating terms. We use the conformal expansion allowing the distribution amplitudes to be described by a set of non-perturbative hadronic parameters which is reduced by invoking the QCD equation of motion to find various interrelations between the distribution amplitudes. Numerical values of the leading non-perturbative hadronie parameters are determined from QCD sum rules. The new distribution amplitude results find direct application in the radiative B decays to light vector mesons B → Vγ. We examine the phenomenologically most important observables in this decay mode using the formalism of QCD factorisation in which the distribution amplitudes play a vital role. We also include long-distance photon emission and soft quark loop effects, which formally lie outside the QCD factorisation formalism. The analysis encompasses all the relevant modes, that is B(_u),(_d)→(_p),(_w),K* and B(_s) → φ,K*.We also calculate the B → n(^1) transition form factor using QCD sum rules on the light- cone. The method relies on the collinear factorisation of the QCD dynamics into a pertur- batively calculable hard-scattering kernel and the non-perturbative universal distribution amplitudes. We include the singlet contribution originating from the U(1)a anomaly and bring the calculation consistently within the n-n(^1) mixing framework
Combination of CDF and D0 results on the W boson mass and width
Get PDFThe results on the direct measurements of the W-boson mass and width, based on the data collected by the Tevatron experiments CDF and D{sup -} at Fermilab are summarized and combined. The CDF Run-0 (1988-1889) and Run-I (1992-1995) results have been re-averaged using the BLUE method and combined with Run-I D{sup -} results and the latest published results from CDF taken from the first period of Run-II (2001-2004). The results are corrected to have consistency between the parton distribution functions and electroweak parameters. The resulting Tevatron averages for the mass and total decay width of the W boson are: M{sub W} = 80432 {+-} 39 MeV and {Lambda}{sub W} = 2056 {+-} 62 MeV. The inclusion of a preliminary Run-II measurement of {Lambda}{sub W} from D{sup -}0 gives {Lambda}{sub W} = 2050 {+-} 58 MeV
Higgs Boson Studies at the Tevatron
Get PDFWe combine searches by the CDF and D0 Collaborations for the standard model Higgs boson with mass in the range 90--200 GeV produced in the gluon-gluon fusion, , , , and vector boson fusion processes, and decaying in the , , , , and modes. The data correspond to integrated luminosities of up to 10 fb and were collected at the Fermilab Tevatron in collisions at TeV. The searches are also interpreted in the context of fermiophobic and fourth generation models. We observe a significant excess of events in the mass range between 115 and 140 GeV/. The local significance corresponds to 3.0 standard deviations at GeV/, consistent with the mass of the Higgs boson observed at the LHC, and we expect a local significance of 1.9 standard deviations. We separately combine searches for , , , and . The observed signal strengths in all channels are consistent with the presence of a standard model Higgs boson with a mass of 125 GeV/
Search for resonances decaying into top-quark pairs using fully hadronic decays in pp collisions with ATLAS at root s=7 TeV
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Combination of CDF and D0 results on the W boson mass and width
No full textThe results based on 1992–95 data (Run 1) from the CDF and D0 experiments on the measurements of the W boson mass and width are presented, along with the combined results. We report a Tevatron collider average MW=80.456±0.059 GeV. We also report the Tevatron collider average of the directly measured W boson width ΓW=2.115±0.105 GeV. We describe a new joint analysis of the direct W mass and width measurements. Assuming the validity of the standard model, we combine the directly measured W boson width with the width extracted from the ratio of W and Z boson leptonic partial cross sections. This combined result for the Tevatron is ΓW=2.135±0.050 GeV. Finally, we use the measurements of the direct total W width and the leptonic branching ratio to extract the leptonic partial width Γ(W→eν)=224±13 MeV
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