Precision Electroweak Measurements and Constraints on the Standard Model

Collaboration, ALEPH; Collaboration, CDF; Collaboration, D0; Collaboration, DELPHI; Collaboration, L3; Collaboration, OPAL; Collaboration, SLD; Group, LEP Electroweak Working; Group, Tevatron Electroweak Working; group, SLD electroweak heavy flavour

doi:10.48550/arxiv.0811.4682

Cited by 13 publications

(21 citation statements)

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“…The most stringent indirect constraints on M Z come from low-energy weak neutral current experiments displayed in Table 2 together with other non Z-pole observables. The first set shown are the most recent combinations of M W [50] and the top quark mass, m t [51].…”

Section: Details Of the Analysesmentioning

confidence: 99%

Improved constraints onZ′ bosons from electroweak precision data

Erler¹,

Langacker²,

Munir³

et al. 2009

J. High Energy Phys.

251

225

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We analyze various models with an extra U (1) gauge symmetry in addition to the Standard Model (SM) gauge group at low energies, and impose limits on the mass of the neutral Z boson, M Z , predicted in all such models, and on the Z − Z mixing angle, θ ZZ . The precision electroweak (EW) data strongly constrain θ ZZ to very small values and for most models we find lower limits on M Z of O(1 TeV). In one case we obtain a somewhat better fit than in the SM (although this is only marginally statistically significant) and here we find a weak upper limit at the 90% C.L.

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Section: Details Of the Analysesmentioning

confidence: 99%

Improved constraints onZ′ bosons from electroweak precision data

Erler¹,

Langacker²,

Munir³

et al. 2009

J. High Energy Phys.

251

225

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“…The branching ratio R b is very sensitive to the NP beyond the SM, the precision experimental value of R b may give a severe constraint on the NP [6]. Experimentally, the electroweak observables have been precisely measured at the SLC and LEP, in the most recent analysis of the electroweak data, R b = 0.21629 ± 0.00066 differs from the SM fit by 0.7σ, A b F B = 0.0992 ± 0.0016 disagrees with the SM fit by −2.9σ [7]. Furthermore, the experimental value of Zb b couplings disagrees with the SM fit by about 3σ, especially the deviation of the right-handed coupling is so large that it is very difficult to explain.…”

Section: Introductionmentioning

confidence: 96%

The study of the contribution of the LHT model to coupling

2011

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In the framework of the Littlest Higgs Model with T-parity (LHT), we study the contributions of the new particles to Zbb couplings at one-loop level. Based on these results, we further study the branching ratio R b and the unpolarized forward-backward asymmetry A b F B . We find that the correction of the new particles to Zbb couplings is mainly on the left-handed coupling and has small part of the parameter space to alleviate the deviation between theoretical predictions and experimental values. The precision measurement value of R b can give severe constraints on the relevant parameters. The constraints from the precision measurement value of A b F B are very weak. PACS numbers: 14.65.Fy,12.15.Mm,13.85.Lg c d 12 c d 13 s d 12 c d 13 e −iδ d 12 s d 13 e −iδ d 13 −s d 12 c d 23 e iδ d 12 − c d 12 s d 23 s d 13 e i(δ d 13 −δ d 23 ) c d 12 c d 23 − s d 12 s d 23 s d 13 e i(δ d 13 −δ d 12 −δ d 23 ) s d 23 c d 13 e −iδ d 23 s d 12 s d 23 e i(δ d 12 +δ d 23 ) − c d 12 c d 23 s d 13 e iδ d 13 −c d 12 s d 23 e iδ d 23 − s d 12 c d 23 s d 13 e i(δ d 13 −δ d 12 ) c d 23 c d 13      (9)

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“…The LEP experiments established a lower bound of 114.4 GeV, at 95% confidence level, on the mass of the SM Higgs boson [3]. On the other hand, the electroweak precision data points towards a relatively light SM Higgs boson with m H < ∼ 185 GeV at 95% confidence level [4]. Recently, Tevatron data have excluded the SM Higgs mass in the range 160 GeV ≤ m H ≤ 170 GeV again at 95% confidence level [5].…”

Section: Introductionmentioning

confidence: 99%

Reconstructing the Higgs boson in dileptonic W decays at hadron collider

Choi,

Lee

et al. 2009

Preprint

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We examine the prospect to measure the Higgs boson mass using the recently introduced kinematic variable, the M T 2 -Assisted On-Shell (MAOS) momentum, that provides a systematic approximation to the invisible neutrino momenta in dileptonic decays of W -boson pair. For this purpose, we introduce a modified version of the MAOS momentum, that is applicable even when one or both of the W -bosons from the Higgs decay are in off-shell. It is demonstrated that the MAOS Higgs mass distribution, constructed with the MAOS neutrino momenta, shows a clear peak at the true Higgs boson mass when an event cut selecting higher value of M T 2 is employed. We perform the likelihood analysis for this MAOS mass distribution to determine the Higgs boson mass, and find it can improve the accuracy of the Higgs mass measurement. Our results indicate that the MAOS Higgs mass can be useful also for the discovery or exclusion of the Higgs boson in certain mass range.

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Precision Electroweak Measurements and Constraints on the Standard Model

Cited by 13 publications

References 0 publications

Improved constraints onZ′ bosons from electroweak precision data

Improved constraints onZ′ bosons from electroweak precision data

The study of the contribution of the LHT model to coupling

Reconstructing the Higgs boson in dileptonic W decays at hadron collider

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