Related papers: Long-Lived Charged Heavy Leptons
We consider a neutrinophilic $U(1)$ extension of the standard model (SM) which couples only to SM isosinglet neutral fermions, charged under the new group. The neutral fermions couple to the SM matter fields through Yukawa interactions. The…
A search for vector-like leptons in multilepton (two, three, or four-or-more electrons plus muons) final states with zero or more hadronic $\tau$-lepton decays is presented. The search is performed using a dataset corresponding to an…
In the context of a left-right symmetric model, we introduce one full generation of vectorlike lepton doublets (both left and right-handed) together with their mirror doublets. We show that the lightest vectorlike neutrino in the model is…
If the Standard Model particle content is extended by gauge singlet fermions (right-handed neutrinos), active neutrinos generically acquire (Majorana) masses, in agreement with our current understanding of the lepton sector. If the…
Minimal extensions of the Standard Model that are motivated by grand unified theories or superstring models with an E_6 symmetry can naturally predict heavy neutrinos of Dirac or Majorana nature. Such heavy neutral leptons violate the de-…
We study the perspective to observe lepton number violating signatures from heavy Majorana neutrino decays at colliders in view of the requirement to explain the light neutrino masses via the seesaw mechanism. In the minimal model with only…
We propose a non-holomorphic modular $A_4$ model under the assumption of universal couplings. In this framework, a charged lepton mass hierarchy is not created through parameter fine tuning or hierarchical Yukawa couplings, but instead is…
Heavy lepton singlets $N$ slightly mixed with a standard neutrino $\nu_\ell$ are usually searched for at the LHC in the trilepton plus $p_{\rm T}^{\rm miss}$ channel: $pp \to W^+ \to \ell^+ N$ with $N\to \ell^- W^+ \to \ell^- \ell'^+ \nu$.…
We study the implications of having a similarity between quark and lepton mixing in the Dirac sector of the Standard Model plus the right-handed neutrino. This enable us to describe all masses and mixings in the Dirac sector in terms of…
We consider the possibility of Majorana neutrinos production at the Large Hadron Collider (LHC) by studying the $pp \rightarrow l_i^{+} l_j^{+} +2~jets$ ($l_j\equiv e ,\mu$) process which, due to leptonic number violation, is a clear…
We construct a neutrino model of three twin neutrinos in light of the neutrino appearance excesses at LSND and MiniBooNE. The model, which includes a twin parity, naturally predicts identical lepton Yukawa structures in the Standard Model…
Left-right symmetric models (LRSM) were proposed to reconcile the apparent parity violation in weak interactions with our intrinsic notion of fundamental parity symmetry. It was quickly realized that LRSM offers a viable framework for…
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…
Long-lived light particles (LLLPs) appear in many extensions of the standard model. LLLPs are usually motivated by the observed small neutrino masses, by dark matter or both. Typical examples for fermionic LLLPs (a.k.a. heavy neutral…
We merge two leading Beyond Standard Model scenarios, namely compositeness and left-right symmetry, and probe the resulting collider signatures in the leptonic case. The constraints on composite models for fermions leave open the…
In this work we prob a class of neutrino mass models at both Large Hadron Collider (LHC) energies 8 TeV and 14 TeV. The focus will be on the new introduced interaction terms between a singlet charged scalar, $S^{\pm}$, and leptons leading…
We propose $S_4$ symmetric four-generation models for charged leptons. Although an $S_4$ symmetric four-generation model has been already proposed, there are some additional symmetries in the model. We construct four-generation models for…
A search is presented in proton-proton collisions at sqrt(s) = 7 TeV for fermionic triplet states expected in type III seesaw models. The search is performed using final states with three isolated charged leptons and an imbalance in…
The existence of extra chiral generations with all fermions heavier than $m_Z$ is strongly disfavored by the precision electroweak data. However the data still allow a few extra generations if the neutral leptons have masses close to 50…
New heavy charged lepton production and decay signatures at future electron-positron colliders are investigated at $\sqrt {s}=500$ GeV. The consequences of model dependence for vector singlets and vector doublets are studied. Distributions…