Search For Resonant Production Of Top Antitop Pairs Decaying Into Multi Jets At The Collider Detector At Fermilab

ABSTRACT: We performed a search for"non-standard model tṫ resonances in the all jets final state channel." The main goal was to examine top-antitop invariant mass spectrum for the presence of narrow resonant states. The data analysis used 2.8fb−1 of CDF data; events were produced at the Tevatron collider in p[bar p] collisions with center-of-mass energy of 1.96 TeV. 2086 data events were analyzed and compared to Standard Model expectation. No evidence for new tṫ resonant production mechanisms was found. Upper limits were placed on the cross-section times branching ratio for resonance production at 805 GeV/c2. For signal modeling we considered leptophobic Z' boson in a topcolor-assisted technicolor model with the width of [capital gamma]= 1.2%MX0.

We performed a search for"non-standard model tt resonances in the all jets final state channel." The main goal was to examine top-antitop invariant mass spectrum for the presence of narrow resonant states. The data analysis used 2.8fb-1 of CDF data; events were produced at the Tevatron collider in pp collisions with center-of-mass energy of 1.96 TeV. 2086 data events were analyzed and compared to Standard Model expectation. No evidence for new tt resonant production mechanisms was found. Upper limits were placed on the cross-section times branching ratio for resonance production at 805 GeV/c2. For signal modeling we considered leptophobic Z' boson in a topcolor-assisted technicolor model with the width of [Gamma] = 1.2%MX0.

This Letter reports a search for non-standard model topquark resonances, Z', decaying to t{bar t} 2!WbW−{bar b}, where both W decay to quarks. We examine the top-antitop quark invariant mass spectrum for the presence of narrow resonant states. The search uses a data sample of p{bar p} collisions at a center of mass energy of 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron, with an integrated luminosity of 2.8 fb−1. No evidence for top-antitop quark resonant production is found. We place upper limits on the production cross section times branching ratio for a specific topcolor assisted technicolor model with width of [Lambda]{sub Z'} = 0.012 M{sub Z'}. Within this model, we exclude Z' boson with masses below 805 GeV/c2 at the 95% confidence level.

A search for undiscovered particles decaying into top-antitop quark pairs produced in proton-proton collisions with the ATLAS experiment at the Large Hadron Collider utilizing 20.3 fb$^-1$ of data collected at $\sqrt{s}=8$ \tev\ center-of-mass energy during the 2012 data taking period is presented. The invariant mass spectrum of events containing multiple jets, exactly one lepton, and missing transverse energy and which are consistent with the decay of a top-antitop quark pair is studied and found to be consistent with that predicted by the Standard Model. Upper limits on the production cross section times branching ratio of several benchmark signal models are set at a 95\% confidence level.

We search for resonant production of t{bar t} pairs in 4.8 fb−1 integrated luminosity of p{bar p} collision data at √s = 1.96 TeV in the lepton+jets decay channel, where one top quark decays leptonically and the other hadronically. A matrix element reconstruction technique is used; for each event a probability density function (pdf) of the t{bar t} candidate invariant mass is sampled. These pdfs are used to construct a likelihood function, whereby the cross section for resonant t{bar t} production is estimated, given a hypothetical resonance mass and width. The data indicate no evidence of resonant production of t{bar t} pairs. A benchmark model of leptophobic Z' → t{bar t} is excluded with m{sub Z'}

The authors investigate the use of the event topology as a tool in the search for the six-jet decay of top-pair production in proton-antiproton collisions at 1.8 TeV. Modified-Fox-Wolfram shape variables, {cflx H}{sub l}, are employed to help distinguish the top-pair signal from the ordinary QCD multi-jet background. The {cflx h}{sub {ell}}'s can be constructed directly from the calorimeter cells or from jets. Events are required to lie in a region of {cflx H}{sub {ell}}-space defined by L{sub {ell}}

A search for low mass resonances decaying to a jet pair in association with an initial state radiation jet or photon is presented. The ISR object acts as the event trigger, and the resonance jet pair is subsequently boosted and reconstructed as a large-radius jet. Novel jet substructure techniques allow for signal jets to be selected over the dominant multi-jet and [gamma]+jet backgrounds. The search uses 36.1 fb−1 of pp collision data at a center-of-mass energy of 13 TeV collected in 2015 and 2016 by the ATLAS detector at the LHC. Resonances are searched for in the mass range of 100-220 GeV, and no significant deviation from the Standard Model is found. Limits are placed on the production cross section of a benchmark leptophobic Z′ model in the context of a dark matter mediator, as well as the Z′-SM coupling.