A potential scenario for Majorana neutrino detection at future lepton colliders

Abstract

The existence of Majorana neutrinos must lead to lepton-number violating processes, and the Majorana nature of neutrinos can only be experimentally verified only via lepton-number violating processes. We propose a new approach to search for Majorana neutrinos at future electron-positron colliders by exploiting this feature. We investigate the ∆L = 2 like-sign dilepton production and find that lepton colliders with different centerof-mass (c.m.) energies have comparative advantages in resonant production of a Majorana neutrino in either light neutrino mass range or heavy mass range. At the future Circular Electron-Positron Collider (CEPC), with 250 GeV c.m. energy and 5 ab −1 integrated luminosity, we find that there could be more significant sensitivity for resonant production of a Majorana neutrino in the mass range of 5-80 GeV than previous results at LEP2 or LHC. At the 1 TeV ILC with 1 ab −1 integrated luminosity, it has better sensitivity while the neutrino mass is larger than 250 GeV.

Monojet search for heavy neutrinos at future $Z$-factories

“…The current experimental constraints are also displayed, including direct searches in colliders [21,22,45] and meson decays [27,[30][31][32], and indirect searches [46,48]. Expected constraints to heavier neutrinos from future Higgs factories and Z-factories are also shown [53,75].…”

“…One can observe that the left halves of the monojet curves rise, which is reasonable because lighter neutrinos are more likely to decay outside of detectors. Despite this, the , DELPHI [45], CMS [21] and ATLAS [22], indirect searches like 0νββ [46], electroweak precision data (EWPD) [48], and meson decays measured by PIENU (π decay) [30,31], T2K (K decay) [27] and Belle (B decay) [32], and expected constraints from future facilities such as dijet method at future Z-factories [53], LNV processes searches at future Higgs factories [75]. The current experimental bounds are shown by solid curves, while the expected future bounds are shown by dashed curves.…”

Final taus and initial state polarization signatures from effective interactions of Majorana neutrinos at future $$e^{+}e^{-}$$ e + e -

“…For √ s = 500 GeV, this background can be estimated to be of order 10 −5 pb adding the three possible final lepton flavors [20]. However, as these channels involve missing energy from the final neutrinos, they can be effectively suppressed by imposing appropriate cuts on the missing energy for the final states with muons and electrons (l = e, μ) [33]. As an advantage over hadron colliders, the c.m.…”

“…The literature using lepton colliders -in past, existing and proposed experiments like the linear ILC [30] or circular colliders like the FCC-ee [31] and the CEPC [32] -to study the production of heavy sterile neutrinos is very extensive: recent studies of the twounit LNV channel e + e − → l ± i l ± j +4jets, with l ± i = e, μ, τ, in electron-positron colliders can be found in e.g. [33][34][35], and other (not necessarily LNV) heavy sterile neutrino mediated processes as e + e − → lν + 2jets [35][36][37][38][39][40][41]. The initial leptons polarization in linear e + e − colliders has been used recently in [34] to show that the comparison of polarized and unpolarized cross-sections in the e + e − → N N channel for the left-right symmetric model can reveal the nature of the heavy neutrino interaction with the SM sector and probe the heavy-light neutrino mixing parameters.…”

Final taus and initial state polarization signatures from effective interactions of Majorana neutrinos at future $e^{+}e^{-}$ colliders

“…The literature using lepton colliders -in past, existing and proposed experiments like the linear ILC [30] or circular colliders like the FCC-ee [31] and the CEPC [32]-to study the production of heavy sterile neutrinos is very extensive: recent studies of the two-unit LNV channel e + e − → l ± i l ± j + 4jets, with l ± i = e, µ, τ , in electron-positron colliders can be found in e.g. [33][34][35], and other (not necessarily LNV) heavy sterile neutrino mediated processes as e + e − → lν + 2jets [35][36][37][38][39][40][41].…”