Same sign di-lepton candles of the composite gluons

Journal of High Energy Physics, Aug 2015

Composite Higgs models, where the Higgs boson is identified with the pseudo-Nambu-Goldstone-Boson (pNGB) of a strong sector, typically have light composite fermions (top partners) to account for a light Higgs. This type of models, generically also predicts the existence of heavy vector fields (composite gluons) which appear as an octet of QCD. These composite gluons become very broad resonances once phase-space allows them to decay into two composite fermions. This makes their traditional experimental searches, which are designed to look for narrow resonances, quite ineffective. In this paper, we as an alternative, propose to utilize the impact of composite gluons on the production of top partners to constrain their parameter space. We place constraints on the parameters of the composite resonances using the 8 TeV LHC data and also assess the reach of the 14 TeV LHC. We find that the high luminosity LHC will be able to probe composite gluon masses up to ∼ 6 TeV, even in the broad resonance regime.

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Same sign di-lepton candles of the composite gluons

Received: May Same sign di-lepton candles of the composite gluons Aleksandr Azatov 0 1 3 6 7 Debtosh Chowdhury 0 1 3 4 7 Diptimoy Ghosh 0 1 3 4 5 7 Tirtha Sankar Ray 0 1 2 3 7 0 Weizmann Institute of Science , Rehovot 7610001 , Israel 1 Piazzale Aldo Moro 2 , I-00185 Rome , Italy 2 Department of Physics, Indian Institute of Technology Kharagpur 3 CERN , Geneva , Switzerland 4 INFN - Sezione di Roma 5 Department of Particle Physics and Astrophysics 6 Theory Division, Physics Department 7 721 302 , India Composite Higgs models, where the Higgs boson is identified with the pseudo-Nambu-Goldstone-Boson (pNGB) of a strong sector, typically have light composite fermions (top partners) to account for a light Higgs. This type of models, generically also predicts the existence of heavy vector fields (composite gluons) which appear as an octet of QCD. These composite gluons become very broad resonances once phase-space allows them to decay into two composite fermions. This makes their traditional experimental searches, which are designed to look for narrow resonances, quite ineffective. In this paper, we as an alternative, propose to utilize the impact of composite gluons on the production of top partners to constrain their parameter space. We place constraints on the parameters of the composite resonances using the 8 TeV LHC data and also assess the reach of the 14 TeV LHC. We find that the high luminosity LHC will be able to probe composite gluon masses up to ∼ 6 TeV, even in the broad resonance regime. Beyond Standard Model; Technicolor and Composite Models 1 Introduction The model setup Details of collider simulation A Event selection criteria A.1 ATLAS: 8 TeV A.2 CMS: 8 TeV A.3 14 TeV projections Minimal composite Higgs model M 45 The discovery of the Higgs boson at the Large Hadron Collider (LHC) [1, 2] has propelled us to the era of Higgs property measurements. Whether the discovered Higgs boson is an elementary or a composite object is an outstanding question, and would be at the cynosure of attention in the second run of the LHC which is about to start in a few months. In this context, models where the Higgs boson is a pNGB of a global symmetry spontaneously broken by a strongly coupled sector, represent well motivated scenarios of electroweak symmetry breaking containing a composite Higgs. [3–5] (see ref. [6] for a recent review). In the models where the Standard Model (SM) fermion masses are generated by the partial compositeness mechanism [7], the strong sector must contain fermionic colored resonances. These, so called, top partners, are crucial to ensure the finiteness of the SM fermion contributions to the radiatively generated potential for the pNGB Higgs [5, 8]. These resonances are expected to be light in order to reproduce the observed mass of the SM Higgs boson without introducing additional tuning into the model [9–13], and their direct search at the LHC [14, 15] already constrains them to be heavier than & 800 GeV. Since the top partners are coloured, generically one expects the presence of coloured vector resonances as well. In this paper we focus on the indirect constraints on the composite vector fields (composite gluons) which are in the adjoint representation of SU(3)Color. They can be identified with the Kaluza-Klein (KK) excitation of the SM gluons in the five-dimensional realizations of the composite scenarios [5]. The two loop contribution of these composite gluons to the Higgs potential is known to soften the fine-tuning in these models [16]. However, the low energy flavour violating observables, especially duction of flavour symmetries [21–26] can make these vector resonances light while being compatible with the flavour observables. In this work, however, we will not rely on any additional symmetries in the flavour sector and assume that there are cancellations among different contributions, allowing the composite gluons to be light and hence, accessible at If the decay of the composite gluon to the top partners is kinematically allowed, typically large couplings of the strong sector imply that the composite gluon will have large width, comparable to its mass. In that case, the traditional approach to search for heavy gluons through resonance hunting may prove ineffective [27]. However, as we will elaborate in this work, these broad resonances can be cornered by several other (cut-and-count) searches being carried out at the LHC. In particular, the gluon partners contribute to the top partner pair production cross-section and this can be used to put useful constraints on them [27].1 In this paper we adopt this approach and recast the studies carried out to search for top partners to constrain the composite gluon parameter space. In particular, our study will focus on the indirect bounds on the parameter space of the composite gluons from the top partner searches with the same sign dilepton final state by the ATLAS [28] and CMS [29] collaborations.2 We will also study the (...truncated)


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Aleksandr Azatov, Debtosh Chowdhury, Diptimoy Ghosh. Same sign di-lepton candles of the composite gluons, Journal of High Energy Physics, 2015, pp. 140, Volume 2015, Issue 8, DOI: 10.1007/JHEP08(2015)140