On the interpretation of Top Partners searches

Matsedonskyi, Oleksii; Panico, Giuliano; Wulzer, Andrea

doi:10.1007/jhep12(2014)097

Cited by 117 publications

(178 citation statements)

References 74 publications

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“…This peculiar state was for example used in composite Higgs models searches [19,20]. The same sign dilepton signature can also arise from the same final state with 4 W 's and 2 b's which is also produced in the case of a b ′ quark decaying into b ′ → W − t → W − W + b, therefore, for example, the bound on the b ′ mass in [21,22] can be directly translated into a bound on the X 5/3 mass because the experimental efficiencies in the two cases are very similar [23]. Both phenomenological studies and the dedicated CMS search consider 100% branching ratio into the top and pair production, while, in realistic set-ups, mixing with light fermions c and u can allow decays into W and a light jet.…”

Section: Introductionmentioning

confidence: 99%

Heavy vector-like quark with charge 5/3 at the LHC

Cacciapaglia

Deandrea

Panizzi

et al. 2013

J. High Energ. Phys.

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We study the phenomenology at the Large Hadron Collider of an exotic vectorlike quark with charge +5/3. We relax the assumption of a 100% branching into W t and allow for an arbitrary rate into W plus light quarks, thus covering all possible scenarios. Sizeable decays into light quarks can be achieved, for instance, in a model where the X 5/3 quark is embedded in a doublet with hypercharge 7/6, which also contains a t ′ quark. We study the bounds on the parameter space of this model, and perform a detailed simulation of the X 5/3 pair production and decays. We show that the final state with W tW q, where q = u or c, contributes to the same sign dilepton searches, and that the reach can be improved with alternative cuts optimised on such final state.

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Section: Introductionmentioning

confidence: 99%

Heavy vector-like quark with charge 5/3 at the LHC

Cacciapaglia

Deandrea

Panizzi

et al. 2013

J. High Energ. Phys.

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“…In addition, the potential applicable scope of this strategy is broad. The first class of examples are some non-SUSY theories, such as little Higgs models [37], composite Higgs models [38], and Randall-Sundrum models [39], where fermionic top partners t with a mass below 1 TeV are typically predicted [40], given a 125 GeV SM-like Higgs boson, and the Higgs boson can be produced via t → ht, a way similar to the second mechanism discussed above. Actually, multiple b-tagging has been noticed to be useful in this context [41], while the Higgs reconstruction was thought to be a big problem due to the combinatorial background [42].…”

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confidence: 99%

Multipleb-jets reveal top superpartners and the 125 GeV Higgs

2013

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We demonstrate that in supersymmetry (SUSY) with relatively light top superpartners, h → b b can be a very promising channel to discover the SM-like Higgs resonance at the Large Hadron Collider (LHC), although in general contexts it is thought to be challenging because of its huge QCD background. In this scenario, the SM-like Higgs boson is mainly produced via cascade decays initiated by pair-produced stop or sbottom squarks. The good sensitivity to h → b b owes a great deal to the application of multiple (≥ 4) b-jet tagging in removing the QCD background, and color-flow variables for reconstructing the Higgs resonance. We show in two benchmark points that a SM-like Higgs resonance can be discovered at the 14 TeV LHC (with a signal-to-background ratio as high as 0.35), with ∼ 40 fb −1 of data. Potentially, this strategy can be also applied to non-SUSY theories with cascade decays of top partners for the SM-like Higgs search, such as little Higgs, composite Higgs, and Randall-Sundrum models.

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“…[17], which show that for typical couplings (in composite Higgs models), single-production channels yield at most comparable and mostly weaker bounds on the quark partner masses than the pair-production channels for LHC run-I. First ATLAS and CMS bounds for single-production (from run-II) are available only since very recently [18][19][20][21][22].…”

Section: A Brief Summary Of Existing Lhc Top Partner Searchesmentioning

confidence: 99%

Search strategies for vector-like quark partners at LHC run-II

Flacke

2017

EPJ Web Conf.

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Abstract. We present results on several new search channels and strategies for heavy vector-like quark partners or vector resonances at the LHC run-II. Run-II has sensitivity to single-and pair-produced quark partners with masses beyond 1 TeV, and for even higher masses for vector resonances. Decays of such heavy particles yield highly boosted tops, Higgses, and weak gauge bosons. At high boost, the Standard Model background of hadronic final states can be substantially suppressed when applying jet-substructure techniques. We present several case studies where the identification of hadronically decaying tops, Higgses, and/or electroweak gauge bosons allow to make new search channels competitive at run-II. Motivation and OverviewNaturalness has for a long time been a guiding principle of theoretical particle physics. While the discovery of the last missing Standard Model SM particle -the Higgs -marks a great success of particle physics, it is difficult to understand why the Higgs mass is so much smaller than the Planck mass. Composite Higgs models provide a possible solution to this hierarchy problem [1,2]. The main idea behind composite Higgs models is to realize the Higgs multilplet as a light bound state of a theory which becomes strongly coupled below a scale of a few TeV. The large hierarchy between the TeV scale and the Planck scale is realized through dimensional transmutation. If the Higgs multiplet is realized as a pseudo-Nambu-Goldstone boson (pNGB) multiplet of a global symmetry of the underlying model, a small hierarchy between the Higgs mass m h , the electroweak scale v and the decay constant f of the pNGB can be realized at the price of a mild fine-tuning. From a low-energy perspective, the most minimal implementation of the composite Higgs paradigm is realized in models with S O(5) → S O(4) breaking [3]. Within such effective field theory descriptions, indirect bounds like deviations of Higgs couplings from the Standard Model (SM) prediction and electroweak precision tests yield constraints of f 500−1000 GeV, depending on the precise model, the top-partner masses, and the underlying UV dynamics. Flavour physics also yields important constraints, as obtaining the observed top mass requires an extended (top-)quark sector with additional sources for flavor changing neutral currents. Partial compositeness of the top can successfully address these flavor problems as recently discussed in [4].On the other hand, composite Higgs models can be tested directly by searching for composite resonances beyond the Higgs. Composite top-partners, scalar-or vector resonances are expected to

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On the interpretation of Top Partners searches

Cited by 117 publications

References 74 publications

Heavy vector-like quark with charge 5/3 at the LHC

Heavy vector-like quark with charge 5/3 at the LHC

Multipleb-jets reveal top superpartners and the 125 GeV Higgs

Search strategies for vector-like quark partners at LHC run-II

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