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Top quark and Electroweak measurements at the Tevatron  [PDF]
L. Cerrito
Physics , 2010, DOI: 10.1088/1742-6596/259/1/012019
Abstract: We present recent preliminary measurements at the Tevatron of t-tbar and single top production cross section, top quark mass and width, top pair spin correlations and forward-backward asymmetry. In the electroweak sector, we present the Tevatron average of the W boson width, and preliminary measurements of the W and Z forward-backward asymmetries and WZ, ZZ diboson production cross sections. All measurements are based on larger amount of collision data than previously used and are in agreement with the standard model.
Review of recent measurements in the top quark sector at the Tevatron  [PDF]
Andreas Werner Jung
Physics , 2014, DOI: 10.1142/S0217732314300146
Abstract: Recent measurements in the top quark sector at the Fermilab Tevatron collider are discussed. Measurements at the Tevatron use up to 9.7/fb of data corresponding to the full data sets recorded by the CDF and D0 experiments, respectively. This review discusses the most recent measurements of inclusive and differential top quark cross sections in strong and electroweak production of top quarks and related measurements, as well as measurements of angular distributions related to asymmetries in top quark production. Furthermore the current status on the precision measurements of the mass of the top quark is discussed. Where available, combinations of CDF and D0 results are presented.
Parity Violating Asymmetries in Top Pair Production at Hadron Colliders  [PDF]
Chung Kao,Doreen Wackeroth
Physics , 1999, DOI: 10.1103/PhysRevD.61.055009
Abstract: We study loop-induced parity violating asymmetries in the strong production of polarized top quark pairs at $pp$ and $p \bar p$ colliders. The electroweak ${\cal O}(\alpha)$ corrections to the helicity amplitudes of $q \bar q \to t \bar t$ and $gg \to t \bar t$ are evaluated in a two Higgs doublet model (2HDM) and the minimal supersymmetric standard model (MSSM). While observables in top quark pair production receive little contribution from standard electroweak interactions, it is possible that they can be significantly enhanced in a 2HDM and the MSSM. We find that the one-loop MSSM electroweak corrections can generate parity violating asymmetries in the total production rate of left- and right-handed top quark pairs up to about 1.7% at the upgraded Tevatron ($\sqrt{S}=2$ TeV) and 3% at the LHC ($\sqrt{S}=14$ TeV).
Asymmetries in top quark pair production at hadron colliders  [PDF]
J. A. Aguilar-Saavedra,D. Amidei,A. Juste,M. Perez-Victoria
Physics , 2014, DOI: 10.1103/RevModPhys.87.421
Abstract: We review the asymmetries in top quark pair production at the Tevatron and the LHC. We summarize the experimental measurements and the interpretations of a possible excess in terms of new physics. We also review other top quark properties-emphasizing effects related to the $t \bar t$ asymmetries-as well as other collider signals.
Measurements of Cross Sections and Forward-Backward Asymmetries at the Z Resonance and Determination of Electroweak Parameters  [PDF]
L3 Collaboration
Physics , 2000, DOI: 10.1007/s100520050001
Abstract: We report on measurements of hadronic and leptonic cross sections and leptonic forward-backward asymmetries performed with the L3 detector in the years 1993-95. A total luminosity of 103 pb^-1 was collected at centre-of-mass energies \sqrt{s} ~ m_Z and \sqrt{s} ~ m_Z +/- 1.8 GeV which corresponds to 2.5 million hadronic and 245 thousand leptonic events selected. These data lead to a significantly improved determination of Z parameters. From the total cross sections, combined with our measurements in 1990-92, we obtain the final results: m_Z = 91189.8 +/- 3.1 MeV, Gamma_Z = 2502.4 +/- 4.2 MeV, Gamma_had = 1741.1 +/- 3.8 MeV, Gamma_l = 84.14 +/- 0.17 MeV. An invisible width of Gamma_inv = 499.1 +/- 2.9 MeV is derived which in the Standard Model yields for the number of light neutrino species N_nu = 2.978 +/- 0.014. Adding our results on the leptonic forward-backward asymmetries and the tau polarisation, the effective vector and axial-vector coupling constants of the neutral weak current to charged leptons are determined to be \bar{g}_V^l = -0.0397 +/- 0.0017 and \bar{g}_A^l = -0.50153 +/- 0.00053.Including our measurements of the Z -> b \bar{b} forward-backward and quark charge asymmetries a value for the effective electroweak mixing angle of sin^2\bar{\theta}_W = 0.23093 +/- 0.00066 is derived. All these measurements are in good agreement with the Standard Model of electroweak interactions. Using all our measurements of electroweak observables an upper limit on the mass of the Standard Model Higgs boson of m_H < 133 GeV is set at 95% confidence level.
Differential and total cross sections for top pair and single top production  [PDF]
Nikolaos Kidonakis
Physics , 2012,
Abstract: I present theoretical results at approximate NNLO from NNLL resummation for top quark production at the LHC and the Tevatron, including new results at 8 TeV LHC energy. Total cross sections are shown for t tbar production, for single top production in the t and s channels and via associated tW production, and for associated tH- production. Top quark transverse momentum and rapidity distributions in t tbar production are also presented, as well as new results for t-channel single top and single antitop pT distributions.
Electroweak and Top Results from ATLAS  [PDF]
Marilyn Marx
Physics , 2013,
Abstract: An overview of recent measurements of electroweak and top quark physics is given. In particular, total and differential diboson cross sections, limits on anomalous triple gauge couplings as well as top quark production cross sections and properties, such as charge asymmetry, top quark polarization and Wtb vertex measurements, are presented. Proton-proton collision data produced at the LHC at sqrt s = 7 TeV and sqrt s = 8 TeV collected with the ATLAS detector are used.
Precision Electroweak Measurements on the Z Resonance  [PDF]
The ALEPH Collaboration,the DELPHI Collaboration,the L3 Collaboration,the OPAL Collaboration,the SLD Collaboration,the LEP Electroweak Working Group,the SLD electroweak,heavy flavour groups
Physics , 2005, DOI: 10.1016/j.physrep.2005.12.006
Abstract: We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLD experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, $\MZ$ and $\GZ$, and its couplings to fermions, for example the $\rho$ parameter and the effective electroweak mixing angle, are precisely measured. The number of light neutrino species is determined to be 2.9840+/-0.0082. The results are compared to the predictions of the Standard Model. Electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its Standard Model expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the masses of the top quark and the W Boson are predicted. These indirect constraints are compared to the direct measurements, providing a stringent test of the Standard Model. Using in addition the direct measurements of $\Mt$ and $\MW$, the mass of the as yet unobserved Standard Model Higgs boson is predicted.
Electroweak top-quark pair production at the LHC with $Z'$ bosons to NLO QCD in POWHEG  [PDF]
R. Bonciani,T. Jezo,M. Klasen,F. Lyonnet,I. Schienbein
Physics , 2015,
Abstract: We present the calculation of the NLO QCD corrections to the electroweak production of top-antitop pairs at the CERN LHC in the presence of a new neutral gauge boson. The corrections are implemented in the parton shower Monte Carlo program POWHEG. Standard Model (SM) and new physics interference effects are properly taken into account. QED singularities, first appearing at this order, are consistently subtracted. Numerical results are presented for SM and $Z'$ total cross sections and distributions in invariant mass, transverse momentum, azimuthal angle and rapidity of the top-quark pair. The remaining theoretical uncertainty from scale and PDF variations is estimated, and the potential of the charge asymmetry to distinguish between new physics models is investigated for the Sequential SM and a leptophobic topcolor model.
Top pair Asymmetries at Hadron colliders with general $Z'$ couplings
Ayazi, Seyed Yaser
High Energy Physics - Phenomenology , 2013,
Abstract: Recently it has been shown that measurement of charge asymmetry of top pair production at LHC excludes any flavor violating $Z'$ vector gauge boson that could explain Tevatron forward-backward asymmetry (FBA). We consider the general form of a $Z'$ gauge boson including left-handed, right-handed vector and tensor couplings to examine FBA and charge asymmetry. To evaluate top pair asymmetries at Tevatron and LHC, we consider $B^0_q$ mixing constraints on flavor changing $Z'$ couplings and show that this model still explain forward-backward asymmetry at Tevatron and charge asymmetry can not exclude it in part of parameters space.
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