Searches for new physics in top events at the Tevatron

During the past years the CDF and D0 detectors have collected large amounts of data obtaining a relatively pure sample of pair-produced top quarks and a well understood sample containing singly-produced top quarks. These samples have been used for the precise measurement of the top quark properties, and have set stringent limits on new physics in the top sample. This reports presents the latest results from the CDF and D0 collaborations on the search for new physics within the top sample using an integrated data sample of up to 3.6 fb-1.Comment: Proceedings for the Moriond 2009 QCD sessio

Evidence for a particle produced in association with weak bosons and decaying to a bottom-antibottom quark pair in Higgs boson searches at the Tevatron

We combine searches by the CDF and D0 Collaborations for the associated production of a Higgs boson with a W or Z boson and subsequent decay of the Higgs boson to a bottom-antibottom quark pair. The data, originating from Fermilab Tevatron pp[over ¯] collisions at √s = 1.96 TeV, correspond to integrated luminosities of up to 9.7 fb⁻¹. The searches are conducted for a Higgs boson with mass in the range 100–150 GeV/c². We observe an excess of events in the data compared with the background predictions, which is most significant in the mass range between 120 and 135 GeV/c². The largest local significance is 3.3 standard deviations, corresponding to a global significance of 3.1 standard deviations. We interpret this as evidence for the presence of a new particle consistent with the standard model Higgs boson, which is produced in association with a weak vector boson and decays to a bottom-antibottom quark pair.Physic

Prospects for top-prime quark discovery at the Tevatron

We show that a top-prime quark as heavy as 600 GeV can be discovered at the Tevatron, provided it is resonantly pair-produced via a vector color octet. If the top-prime originates from a vectorlike quark, then the production of a single top-prime in association with a top may also be observable, even through its decay into a Higgs boson and a top. A color octet with mass of about 1 TeV, which decays into a top-prime pair, may account for the CDF excess of semileptonic (Wj)(Wj) events.Comment: 22 pages, 6 ps figures. v2: Note added about the new D0 search for (Wb)(Wb) resonances; section 4.1 expanded; single-top constraint updated in section 2; references adde

Tevatron Run II combination of the effective leptonic electroweak mixing angle

Drell-Yan lepton pairs produced in the process pp¯→ℓ+ℓ−+X through an intermediate γ∗/Z boson have an asymmetry in their angular distribution related to the spontaneous symmetry breaking of the electroweak force and the associated mixing of its neutral gauge bosons. The CDF and D0 experiments have measured the effective-leptonic electroweak mixing parameter sin2θlepteff using electron and muon pairs selected from the full Tevatron proton-antiproton data sets collected in 2001-2011, corresponding to 9-10 fb−1 of integrated luminosity. The combination of these measurements yields the most precise result from hadron colliders, sin2θlepteff=0.23148±0.00033. This result is consistent with, and approaches in precision, the best measurements from electron-positron colliders. The standard model inference of the on-shell electroweak mixing parameter sin2θW, or equivalently the W-boson mass MW, using the \textsc{zfitter} software package yields sin2θW=0.22324±0.00033 or equivalently, MW=80.367±0.017GeV/c2

Observation of s-channel production of single top quarks at the Tevatron

This is the published version. Copyright 2014 American Physical SocietyWe report the first observation of single-top-quark production in the s channel through the combination of the CDF and D0 measurements of the cross section in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb-1 per experiment. The measured cross section is σs=1.29+0.26−0.24 pb. The probability of observing a statistical fluctuation of the background to a cross section of the observed size or larger is 1.8×10−10, corresponding to a significance of 6.3 standard deviations for the presence of an s-channel contribution to the production of single-top quarks

Heavy Flavours in Collider Experiments

Current issues in the studies of Heavy Flavours in colliders are described with particular emphasis on experiments in which the UK is involved. Results on charm production at HERA are examined and compared to those at the Tevatron. B production rates at the Tevatron as well as the status of B lifetimes and mixing in the LEP collaborations and at the Tevatron are highlighted. The measurement of sin2beta from CDF is described as well as the most recent results on top physics at the Tevatron

Combination of CDF and D0 results on the W boson mass and width

The 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