Abstract
We study displaced vertex signatures of long-lived particles (LLPs) from exotic Higgs decays in the context of a Higgs-portal model and a neutral-naturalness model at the circular electron positron collider (CEPC) and future circular collider ${e}^{+}\text{ }{e}^{\ensuremath{-}}$ (FCC-ee). Such two models feature two representative mass ranges for LLPs, which show very different behavior in their decay signatures. The Higgs-portal model contains a very light sub-GeV scalar boson stemming from a singlet scalar field appended to the Standard Model. Such a light scalar LLP decays into a pair of muons or pions, giving rise to a distinctive signature of collimated muon-jet or pion-jet, thanks to the sub-GeV mass. On the other hand, the neutral-naturalness model, e.g., folded supersymmetry, predicts the lightest mirror glueball of mass $O(10)\text{ }\text{ }\mathrm{GeV}$, giving rise to long decays with a large transverse impact parameter because of the relatively large mass. Utilizing such distinct characteristics to remove the background, we estimate the sensitivities of searches for light scalar bosons and mirror glueballs at the CEPC and FCC-ee. We find either complementary or stronger coverage compared to the previous results in the similar contexts.
Highlights
Since the discovery of a Standard Model (SM)-like Higgs boson at the LHC in 2012 [1,2], there has been no sign of new physics in collider experiments so far
We have investigated the potential of the future e−eþ colliders operated as the Higgs factories, with the profiles of circular electron positron collider (CEPC) and future circular collider eþ e− (FCC-ee) as examples, in detecting the longlived particles predicted by a number of models beyond the SM
The decay of the sub-GeV scalar boson gives rise to a pair of collimated muons or pions, which provides a distinctive signature against possible SM backgrounds
Summary
Since the discovery of a Standard Model (SM)-like Higgs boson at the LHC in 2012 [1,2], there has been no sign of new physics in collider experiments so far. We use a Higgs-portal model and a dark glueball model as the prototype models These models share the same features that the neutral LLPs are scalar bosons pair produced from the SM Higgs decays and followed by their predominant decays into a pair of leptonic or hadronic jets. Because of the light mass, it will be traveling with a high transverse momentum in the Higgs decay, such that the opening angle between the dimuons would be order ΔRμμ ∼ 2mhs =pT 1⁄4 Oð10−2Þ Making use of this feature one can effectively eliminate the background events. Given the relatively large mass of the mirror glueball, the b-jet pair will have a wide opening angle These two models provide two distinct representatives in the search of such LLPs. The organization of this paper is as follows.
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