Search for the singlet vector-like lepton at future $$e^+ e^-$$ colliders

Abstract

Searching for the new particles beyond the standard model (SM) is an important way to probe new physics beyond the SM. In one class of new particles there are nonchiral color singlet fermions that couple to the SM leptons, that is vector-like leptons (VLLs), which have been widely concerned in experiment and theory. The existing literature shows that the singlet VLLs suffer from a big difficult challenge for discovery at future proton-proton colliders. In this paper, we study the prospects of searching for the singlet VLLs in pure leptonic and fully hadronic channels at $$e^+ e^-$$ e + e - colliders. We find that there is an opportunity for excluding the region $$m_{\tau ^{\prime \pm }} \in $$ m τ ′ ± ∈ [180 GeV, 240 GeV] with $${\mathcal {L}}$$ L $$\in $$ ∈ [$$3.0\hbox { fb}^{-1}$$ 3.0 fb - 1 , $$14.9\hbox { fb}^{-1}$$ 14.9 fb - 1 ] ([$$0.1\hbox { fb}^{-1}$$ 0.1 fb - 1 , $$0.3\hbox { fb}^{-1}$$ 0.3 fb - 1 ]) at ILC of $$\sqrt{s} = 500\ \hbox { GeV}$$ s = 500 GeV , the region $$m_{\tau ^{\prime \pm }} \in $$ m τ ′ ± ∈ [240 GeV, 450 GeV] with $${\mathcal {L}} \in $$ L ∈ [$$9.9\hbox { fb}^{-1}$$ 9.9 fb - 1 , $$23.1\hbox { fb}^{-1}$$ 23.1 fb - 1 ] ([$$0.2\hbox { fb}^{-1}$$ 0.2 fb - 1 , $$0.3\hbox { fb}^{-1}$$ 0.3 fb - 1 ]) at ILC of $$\sqrt{s} = 1000\ \hbox { GeV}$$ s = 1000 GeV and the region $$m_{\tau ^{\prime \pm }} \in $$ m τ ′ ± ∈ [450 GeV, 700 GeV] with $${\mathcal {L}} \in $$ L ∈ [$$52.1\hbox { fb}^{-1}$$ 52.1 fb - 1 , $$197.9\hbox { fb}^{-1}$$ 197.9 fb - 1 ] ([$$2.21\hbox { fb}^{-1}$$ 2.21 fb - 1 , $$4.5\hbox { fb}^{-1}$$ 4.5 fb - 1 ]) at CLIC of $$\sqrt{s} = 1500\ \hbox {GeV}$$ s = 1500 GeV in the pure leptonic (fully hadronic) channel. It is more optimistic for excluding and discovering the singlet VLL through the fully hadronic channel at future high energy $$e^+ e^-$$ e + e - colliders.

Report of the Topical Group on Physics Beyond the Standard Model at Energy Frontier for Snowmass 2021

“…Fig- ure18 shows the VLL pair-production cross-sections as a function of M τ for e + e − collisions at √ s = 1000 GeV in the Singlet VLL model and √ s = 3000 GeV in the Doublet VLL model for various choices of the beam polarizations. One sensitivity study for the ILC and CLIC, performed in a fully leptonic final state, suggests that almost the entire accessible range of M τ for each collider energy could be excluded with 15 fb −1 (ILC 500 GeV), 23 fb −1 (ILC 1.0 GeV), and 200 fb −1 (CLIC 1.5 TeV) [316]. In fully hadronic final states the required luminosities decrease considerably, offering strong promise for discovery of a Singlet VLL.…”

Alternative signatures of the quintuplet fermions at the LHC and future linear colliders

“…However, the contribution in the total cross-section is not so large due to destructive interference between the s-ans the t-channel diagrams. The effect of the polarization of the electron and positron beam has been discussed in detail in Ref: [60], and we have followed the exact same polarization of the e + and e − beam which leads to maximum -60% left right asymmetry (A LR )…”

Mechanism of singlet-like vector lepton production and Higgs autocoupling in future positive-negative electric lepton colliders

“…Literature [7] studies the topic of finding VLL in the half-photon channel of the high-energy e~+e~-collider, based on the different decay modes of the electroweak standard boson, the signal is divided into two modes, A and B, and detailed detector simulations are carried out respectively, and it is found that the A mode is more capable of ruling out and discovering the VLL. The construction of new particles that extend beyond the Standard Model is a significant way to explore new physics beyond the Standard Model, according to literature [8].…”