Related papers: Effective field theory for vector-like leptons and…
We study the impact of heavy vector-like leptons on several observables in collider and low-energy physics. These states, present in many well-motivated extensions of the Standard Model, can induce lepton flavour violation and non-standard…
Heavy vector-like quarks (VLQs) appear in many models of beyond the Standard Model physics. Direct experimental searches require these new quarks to be heavy, $\gsim$ 800-1000 GeV. We perform a global fit of the parameters of simple VLQ…
We reanalyze the effective field theory approach for the scenario in which the particles that account for the dark matter (DM) in the universe are vector states that interact only or mainly through the Standard Model-like Higgs boson…
If neutrinos are Dirac particles and, as suggested by the so far null LHC results, any new physics lies at energies well above the electroweak scale, the Standard Model effective field theory has to be extended with operators involving the…
A vector-like extension of the standard model for heavier quarks and leptons with $SU(2)\times U(1)$ gauge symmetry and only one Higgs doublet is examined. This scheme incorporates infinitely many fermions and avoids the appearance of a…
In this paper, a model inspired by Grand Unification principles featuring three generations of vector-like fermions, new Higgs doublets and a rich neutrino sector at the low scale is presented. Using the state-of-the-art Deep Learning…
A search for new physics in top quark production with additional final-state leptons is performed using data collected by the CMS experiment in proton-proton collisions at $\sqrt{s}$ = 13 TeV at the LHC during 2016-2018. The data set…
Signs of new physics are probed in the context of an Effective Field Theory using events containing one or more top quarks in association with additional leptons. Data consisting of proton-proton collisions at a center-of-mass energy of…
Flavor Democracy Hypothesis favors existence of iso-singlet quarks and vector-like charged leptons. Their observation at future colliders could shed light on the nature of mass and mixing patterns of known leptons and quarks, as well as…
Vectorlike leptons are an intriguing possibility for physics beyond the Standard Model. We study the reach for discovering (at 5$\sigma$ significance) or excluding (at 95 per cent confidence) models of charged vectorlike leptons that mix…
We demonstrate the potential of fully leptonic cascade decays of a heavy neutral Higgs boson through vectorlike leptons as a simultaneous probe for extended Higgs sectors and extra matter particles at the LHC. The processes we explore are…
We study a supersymmetric extension of the vector-like lepton scenario, such that the vacuum instability induced by large lepton Yukawa couplings is lifted by the presence of superpartners at or below the TeV scale. In order to preserve the…
A search for pair-production of vector-like leptons is presented, considering their decays into a third-generation Standard Model (SM) quark and a vector leptoquark ($U_1$) as predicted by an ultraviolet-complete extension of the SM,…
A search for pair production of vector-like leptons coupling to first- and second-generation Standard Model leptons is presented. The search is based on a dataset of proton-proton collisions at $\sqrt{s}=13$ TeV recorded with the ATLAS…
The Standard Model Effective Field Theory (SMEFT) and the Low Energy Effective Field Theory (LEFT) can be extended by adding additional spin 0, 1/2 and 1 dark matter particles which are singlets under the Standard Model (SM) gauge group. We…
Events containing one or more top quarks produced with additional prompt leptons are used to search for new physics within the framework of an effective field theory (EFT). The data correspond to an integrated luminosity of 41.5 fb$^{-1}$…
We study the self conjugate dark matter (DM) particles interacting primarily with the standard model leptons in an effective field theoretical frame work. We consider SM gauge invariant effective contact interactions between the Majorana…
When a new heavy particle is discovered at the LHC or at a future high-energy collider, it will be interesting to study its decays into Standard Model particles using an effective field-theory framework. We point out that the proper…
We study a simple effective field theory incorporating six heavy vector bosons together with the standard-model field content. The new particles preserve custodial symmetry as well as an approximate left-right parity symmetry. The enhanced…
We examined the influence of additional scalar doublet on the parameter space of the Standard Model supplemented with a generation of new vector like leptons. In particular we identified the viable regions of parameter space by inspecting…