Charged Lepton Research Articles

Contribution of BSM Particles on Electric Dipole Moment of Charged Leptons in the Minimal Left-Right Symmetric Model

In this paper, the contribution of Beyond the Standard Model (BSM) particles on the Electric Dipole Moment (EDM) of charged lepton is calculated in a minimal Left-Right Symmetric Model. First-order quantum correction i.e., one loop correction, from relevant diagrams in the unitary gauge using Feynman parameterization is used because there is no tree-level contribution in Electric Dipole Moment due to non-renormalizability of the dipole term in the Lagrangian. This study mainly focuses on the BSM Higgs sector contribution to the EDM of charged leptons due to phenomenological interest. CP violation is directly connected to the EDM of fundamental particles. Matter-antimatter asymmetry is a mystery of the universe that demands CP symmetry to be violated. The standard model cannot explain the observed CP violation. Standard Model (SM) is so far the best description of nature. Despite having tremendous success, e.g., Electro-weak Symmetry Breaking and Higgs discovery, the Standard model is not complete. Moreover, experimentally, we observed small neutrino mass and neutrino mixing. The Seesaw Mechanism can explain neutrino mass smallness and mixing introducing a large Majorana mass. Left-right symmetric model is the most natural extension of SM which can accommodate the Seesaw mechanism. So EDM contributions from BSM particles in the Left-Right symmetric Model are a good probe of new physics beyond the SM. These contributions then can be used to do phenomenology and test the Model.

Doubly-charged scalars of the minimal left-right symmetric model at muon colliders

We investigate the prospects of probing the doubly-charged scalars of the minimal Left-Right Symmetric model (MLRSM) at a muon collider. We assess its capability by studying the production of doubly-charged scalars and their subsequent decay into four charged lepton final states containing the same-charge lepton pairs. We find that the channels with same-charge electron and muon pairs, i.e., (e±e±μ∓μ∓ and its charge conjugated pairs), have the largest sensitivity due to the lowest Standard Model background. Besides, we show that the possibility of using fully polarized initial muon beams in the muon collider can enhance the detection sensitivity of doubly-charged scalars of the MLRSM. Furthermore, we show that one can put exclusion limits on the magnitudes of triplet Yukawa couplings that are directly related to the neutrino sector of the MLRSM for the mass range 1.1−5 TeV of the doubly-charged scalars.

Radiative neutrino mass with electroweak scale Majorana dark matter in the Scotogenic model

Non-zero neutrino mass and dark matter (DM) overshadow the success of the Standard Model (SM) of particle physics. The most straightforward extension of the SM to explain these two issues is the Scotogenic model, where the SM particle spectrum extends with three isospin singlet right-handed neutrinos and one doublet scalar, all odd under a Z2 symmetry. The neutrino masses and mixings result from the Weinberg operator induced at one-loop level. The particle spectrum of this model contains a few weakly interacting stable massive particles, each of which can be a good candidate for DM. In this work, we have considered the lightest right-handed neutrino as DM candidate. The Yukawa couplings that give rise to the observed flavor mixings in the neutrino sector also lead to flavor violation in the SM charged lepton sector and hence, get tightly constrained from the charged lepton flavor violating (CLFV) observables. The same Yukawa couplings also contribute to the DM annihilation in the early universe and hence, determine the relic density of the DM. In this work, we address the tension between the constraints from CLFV observables and measured DM relic density to obtain the large Yukawa couplings with the help of a parameterization that reduces the phenomenology relevant parameters to merely three and enhances the detection prospect at the collider experiments. We have explored the parameter space consistent with current CLFV bounds, the observed DM relic density, and the absolute neutrino mass limit. To search for these scenarios, we have identified two promising signals at the proposed lepton colliders: the mono-photon plus missing energy and di-lepton plus missing energy signals. We have studied the collider phenomenology of these signatures and estimated the 5σ detection required luminosity for the center of mass energies at 500 GeV and 1 TeV.

A 3HDM with Z[formula omitted] Z[formula omitted] model for nearly co-bimaximal mixing

We suggest a combination of Z4⋊Z4 symmetry with the B−L gauge model in the framework of three-Higgs-doublet model (3HDM). The co-bimaximal mixing pattern is broken by the charged lepton contribution which can accommodate the global analysis of neutrino oscillation data. The tiny of the light neutrino masses and neutrino mass hierarchy are produced by the type-I seesaw mechanism. The charged-lepton mass hierarchy is naturally achieved and the constraints on the efictive neutrino masses are in good agreement with the recent experimental bounds.

Search for long-lived heavy neutral leptons with lepton flavour conserving or violating decays to a jet and a charged lepton

A search for long-lived heavy neutral leptons (HNLs) is presented, which considers the hadronic final state and coupling scenarios involving all three lepton generations in the 2–20 GeV HNL mass range for the first time. Events comprising two leptons (electrons or muons) and jets are analyzed in a data sample of proton-proton collisions, recorded with the CMS experiment at the CERN LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb−1. A novel jet tagger, based on a deep neural network, has been developed to identify jets from an HNL decay using various features of the jet and its constituent particles. The network output can be used as a powerful discriminating tool to probe a broad range of HNL lifetimes and masses. Contributions from background processes are determined from data. No excess of events in data over the expected background is observed. Upper limits on the HNL production cross section are derived as functions of the HNL mass and the three coupling strengths VℓN to each lepton generation ℓ and presented as exclusion limits in the coupling-mass plane, as lower limits on the HNL lifetime, and on the HNL mass. In this search, the most stringent limit on the coupling strength is obtained for pure muon coupling scenarios; values of |VμN2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {V}_{\\mu \ extrm{N}}^2 $$\\end{document}| > 5 (4) × 10−7 are excluded for Dirac (Majorana) HNLs with a mass of 10 GeV at a confidence level of 95% that correspond to proper decay lengths of 17 (10) mm.

Observation of WWγ Production and Search for Hγ Production in Proton-Proton Collisions at sqrt[s]=13 TeV.

The observation of WWγ production in proton-proton collisions at a center-of-mass energy of 13TeV with an integrated luminosity of 138 fb^{-1} is presented. The observed (expected) significance is 5.6 (5.1) standard deviations. Events are selected by requiring exactly two leptons (one electron and one muon) of opposite charge, moderate missing transverse momentum, and a photon. The measured fiducial cross section for WWγ is 5.9±0.8(stat)±0.8(syst)±0.7(modeling) fb, in agreement with the next-to-leading order quantum chromodynamics prediction. The analysis is extended with a search for the associated production of the Higgs boson and a photon, which is generated by a coupling of the Higgs boson to light quarks. The result is used to constrain the Higgs boson couplings to light quarks.

Z′ induced forward dominant processes in μTRISTAN experiment

General U(1) extension of the Standard Model (SM) is a well motivated beyond the Standard Model (BSM) scenario where three generations of right handed neutrinos (RHNs) are introduced to cancel gauge and mixed gauge-gravity anomalies. After the U(1)X is broken, RHNs participate in the seesaw mechanism to generate light neutrino masses satisfying neutrino oscillation data. In addition to that, a neutral gauge boson Z′ is evolved which interacts with the left and right handed fermions differently manifesting chiral nature of the model which could be probed in future collider experiments. As a result, if we consider μ+e− and μ+μ+ collisions in μTRISTAN experiment Z′ mediated 2→2 scattering will appear in t− and u-channels depending on the initial and final states being accompanied by the photon and Z mediated interactions. This will result well motivated resulting forward dominant scenarios giving rise to sizable left-right asymmetry. Estimating constraints on general U(1) coupling from LEP-II and LHC for different U(1)X charges, we calculate differential and integrated scattering cross section and left-right asymmetry for μ+e−→μ+e− and μ+μ+→μ+μ+ processes which could be probed at μTRISTAN experiment further enlightening the interaction between Z′ and charged leptons and the U(1)X breaking scale.

LHC study of third-generation scalar leptoquarks with machine-learned likelihoods

We study the impact of machine-learning algorithms on LHC searches for leptoquarks in final states with hadronically decaying tau leptons, multiple b-jets, and large missing transverse momentum. Pair production of scalar leptoquarks with decays only into third-generation leptons and quarks is assumed. Thanks to the use of supervised learning tools with unbinned methods to handle the high-dimensional final states, we consider simple selection cuts which would possibly translate into an improvement in the exclusion limits at the 95% confidence level for leptoquark masses with different values of their branching fraction into charged leptons. In particular, for intermediate branching fractions, we expect that the exclusion limits for leptoquark masses extend to ∼1.3 TeV. As a novelty in the implemented unbinned analysis, we include a simplified estimation of some systematic uncertainties with the aim of studying their possible impact on the stability of the results. Finally, we also present the projected sensitivity within this framework at 14 TeV for 300 fb−1 and 3000 fb−1 that extends the upper limits to ∼1.6 TeV and ∼1.8 TeV, respectively. Published by the American Physical Society 2024

Generalized missing partner mechanism for SU(5) GUT inflation

Embedding inflation within a grand unified theory is an intriguing idea towards a more fundamental understanding of particle physics and cosmology. However, within the framework of supersymmetric SU(5) grand unified theory inflation, models typically feature light color octets and weak triplets that ruin the successful gauge coupling unification of the mimimal supersymmetric Standard Model. We present a new possibility for naturally splitting the electronlike states from the colored ones within vectorlike 10-plets by utilizing their couplings with 40-plets that lack electronlike states. Together with the extra light weak doublets from the double missing partner mechanism, the appearance of the light electronlike states from our proposed generalized missing partner mechanism restores gauge coupling unification. Remarkably, the same vectorlike 10-plets cure the bad mass relations between the down quarks and the charged leptons. Discovering the light relic states at future colliders would provide a “smoking gun” signal of the scenario. Published by the American Physical Society 2024

Limits on ALP-neutrino couplings from loop-level processes

We obtain new bounds on effective axionlike particle (ALP)-neutrino interactions from their loop-level impact on the ALP couplings to electroweak gauge bosons γZ, ZZ and W+W−. Both types of interactions are connected via the chiral anomaly, which allows to overcome the fermion mass suppression of tree-level analyses. ALP couplings to charged leptons are considered simultaneously with ALP-neutrino ones, as required by gauge invariance. Complete one-loop computations are presented together with relevant kinematic limits. We leverage data obtained from rare meson decay measurements alongside observations from collider experiments, among others. The novel constraints are particularly competitive for ALP masses ≳100 MeV, evidencing the powerful potential of future ALP searches at colliders which target its couplings to electroweak gauge bosons. Published by the American Physical Society 2024

Discriminating Majorana and Dirac heavy neutrinos at lepton colliders

In this paper we investigate how well the nature of heavy neutral leptons can be determined at a future lepton collider, after its potential discovery. Considered in a simplified model are prompt decays of the neutrino in the mass range from 100 GeV to 10 TeV. We study event selection and application of multivariate analyses to determine whether such a newly discovered particle is of the Dirac or Majorana nature. Combining lepton charge and kinematic event variables, we find that the nature of a heavy neutrino, whether it is a Dirac or a Majorana particle, can be determined at 95% C.L. almost in the whole discovery range. We will briefly speculate about other than the studied channels and the robustness of this statement in more general models of heavy neutral leptons, particularly on the complementarity of high-energy electron-positron vs. muon colliders on resolving the flavor structure of heavy neutrinos.

Electron EDM and LFV decays in the light of Muon (g-2)μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(g-2)_\\mu $$\\end{document} with U(2) flavor symmetry

We study the interplay of New Physics (NP) among the lepton magnetic moment, the lepton flavor violation (LFV) and the electron electric dipole moment (EDM) in light of recent data of the muon (g-2)μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(g-2)_\\mu $$\\end{document}. The NP is discussed in the leptonic dipole operator with the U(2) flavor symmetry of the charged leptons, where possible CP violating phases of the three family space are taken into account. It is remarked that the third-family contributes significantly to the LFV decay, μ→eγ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu \\rightarrow e\\gamma $$\\end{document}, and the electron EDM. The experimental upper-bound on μ→eγ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu \\rightarrow e\\gamma $$\\end{document} decay gives a severe constraint on the parameters of the flavor model. The predicted electron EDM is rather large due to the CP violating phases in the three family space. In addition, we also study (g-2)e,τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(g-2)_{e,\ au }$$\\end{document} of the electron and tauon, and EDMs of the muon and tauon as well as the τ→eγ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ au \\rightarrow e \\gamma $$\\end{document} and τ→μγ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ au \\rightarrow \\mu \\gamma $$\\end{document} decays. The τR→μLγ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ au _R \\rightarrow \\mu _L \\gamma $$\\end{document} decay is predicted to be close to the experimental upper-bound.

Unitarity bounds on the massive spin-2 particle explanation of muon g-2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$g-2$$\\end{document} anomaly

Motivated by the long-standing discrepancy between the Standard Model prediction and the experimental measurement of the muon magnetic dipole moment, we have recently proposed to interpret this muon g-2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$g-2$$\\end{document} anomaly in terms of the loop effect induced by a new massive spin-2 field G. In the present paper, we investigate the unitarity bounds on this scenario. We calculate the s-wave projected amplitudes for two-body elastic scatterings of charged leptons and photons mediated by G at high energies for all possible initial and final helicity states. By imposing the condition of the perturbative unitarity, we obtain the analytic constraints on the charged-lepton-G and photon-G couplings. We then apply our results to constrain the parameter space relevant to the explanation of the muon g-2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$g-2$$\\end{document} anomaly.

Rising through the ranks: flavor hierarchies from a gauged SU(2)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\varvec{\\mathrm {SU(2)}}}$$\\end{document} symmetry

We propose an economical model to address the mass hierarchies of quarks and charged leptons. The light generations of the left-handed fermions form doublets under an SU(2)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \ extrm{SU}(2) $$\\end{document} flavor symmetry, which is gauged. The generational hierarchies emerge from three independent rank-one contributions to the Yukawa matrices: one is a renormalizable contribution, the second is suppressed by a mass ratio, and the last by an additional loop factor. The model is renormalizable, features only a handful of new fields, and is remarkably simple compared to typical completions of gauged flavor symmetries or Froggatt–Nielsen. The model has a rich phenomenology, and we highlight promising signatures, especially in the context of K and B meson physics. This includes an interpretation of the latest B+→K+νν¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B^+ \\rightarrow K^+ \ u \\bar{\ u }$$\\end{document} measurement from Belle II.

Revisiting Trimaximal TM2 mixing in two A4 modular symmetries

In this paper, we discuss a minimal lepton flavor model with two modular [Formula: see text] symmetries, one acting on neutrinos and the other acting on charged leptons. Two corresponding moduli fields are restricted at stabilizers. To avoid vanishing or degenerate lepton masses, the stabilizer in the charged lepton sector always preserves a [Formula: see text] symmetry, and that in the neutrino preserves a [Formula: see text] symmetry. By scanning all viable stabilizers, a unique Trimaximal TM2 mixing is predicted. However, the prediction of the lightest neutrino mass and the mass parameter in neutrinoless double beta decay, as well as two Majorana phases, are different and classified into three cases.

Dynamical scoto-seesaw mechanism with gauged B−L symmetry

We propose a dynamical scoto-seesaw mechanism using a gauged B−L symmetry. Dark matter is reconciled with neutrino mass generation, in such a way that the atmospheric scale arises , while the solar scale is , arising radiatively from the exchange of “dark” states. This way we “explain” the solar-to-atmospheric scale ratio. The TeV-scale seesaw mediator and the two dark fermions carry different B−L charges. Dark matter stability follows from the residual matter parity that survives B−L breaking. Besides having collider tests, the model implies sizable charged lepton flavor violating (cLFV) phenomena, including Goldstone boson emission processes. Published by the American Physical Society 2024

Constraining flavoured leptoquarks with LHC and LFV

We consider the framework of flavoured leptoquarks, in models with scalar or vector leptoquarks, and look for constraints to the parameter space of these models. Using primarily direct searches at the Large Hadron Collider (LHC) and precision processes that probe Lepton Flavour Violation (LFV), we present lower bounds for the masses of the leptoquarks in different flavoured scenarios. We classify the models according to the specific leptoquark, distinguished with respect to their couplings to charged leptons (lepton isolation, two-columned patterns) and in scenarios with specific hierarchies in the couplings (hierarchical, 2-3 democratic, and flipped).

B meson anomalies and large B+→K+νν¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {B}^{+}\ o {K}^{+}\ u \\overline{\ u} $$\\end{document} in non-universal U(1)′ models

In view of both the latest LHCb measurement of RK∗\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {R}_{K^{\\left(\\ast \\right)}} $$\\end{document} and the new 2.7σ deviation reported by Belle II on B+→K+νν¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {B}^{+}\ o {K}^{+}\ u \\overline{\ u} $$\\end{document} decays, we present a fit to the B meson anomalies for various one and two dimensional hypothesis including complex Wilson coefficients. We show in a model-independent way that the generic non-universal U(1)′ extensions of the SM, without flavour violation, fail to simultaneously fit those observables and corroborate that they can modify BRB+→K+νν¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \ extrm{BR}\\left({B}^{+}\ o {K}^{+}\ u \\overline{\ u}\\right) $$\\end{document} up to only a 10%. In view of this deficit, we propose a new way in which those models can accommodate the data at tree level by introducing lepton flavour violating couplings and non-diagonal elements of the charged lepton mixing matrix, with implications in future charged lepton flavour violation searches.

Heavy neutral lepton corrections to SM boson decays: lepton flavour universality violation in low-scale seesaw realisations

We study lepton flavour universality violation in SM boson decays in low-scale seesaw models of neutrino mass generation, also addressing other electroweak precision observables. We compute the electroweak next-to-leading order corrections, which turn out to be important – notably in the case of the invisible decay width of the Z boson, for which the corrections can be as large as the current experimental uncertainty. As a well-motivated illustrative study case, we choose a realisation of the Inverse Seesaw mechanism, and discuss the complementary role of lepton flavour conserving, lepton flavour violating and precision observables, both in constraining and in probing such models of neutrino mass generation. Our findings suggest that invisible Z decays are especially important, potentially at the origin of the most stringent constraints for certain regimes of the Inverse Seesaw (while complying with charge lepton flavour violation and other electroweak precision tests). We also discuss the probing power of the considered observables in view of the expected improvement in experimental precision at FCC-ee.

Neutrino mass models at μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu $$\\end{document}TRISTAN

We study the prospects of probing neutrino mass models at the newly proposed antimuon collider μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu $$\\end{document}TRISTAN, involving μ+e-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu ^+e^-$$\\end{document} scattering at s=346GeV\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{s}= 346~\ ext {GeV}$$\\end{document} and μ+μ+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu ^+\\mu ^+$$\\end{document} scattering at s=2TeV.\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{s}= 2~\ ext {TeV}.$$\\end{document} We show that μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu $$\\end{document}TRISTAN is uniquely sensitive to leptophilic neutral and doubly-charged scalars naturally occurring in various neutrino mass models, such as Zee, Zee–Babu, cocktail, and type-II seesaw models, over a wide range of mass and coupling values, well beyond the current experimental constraints. It also allows for the possibility to correlate the collider signals with neutrino mixing parameters and charged lepton flavor violating observables.