Related papers: Z' Decays into Four Fermions
Exotic leptons in large gauge multiplets, appearing in many scenarios beyond the Standard Model (SM), can be produced at the LHC in pairs or association. Owing to their large masses, their eventual decay products -- SM leptons and bosons --…
We consider a mechanism for neutrino mass generation, based on a local B-L extension of the standard model, which becomes a linear seesaw regime for light neutrinos after spontaneous symmetry breaking. The spectrum of extra particles…
We discuss predictions for the lepton-flavour changing decays Z --> e mu, mu tau, e tau which may be searched for at the Giga-Z option of the Tesla Linear Collider project with Z resonance production rates as high as 10^9. We try to be as…
The discovery of a new boson with a mass of approximately 125 GeV in 2012 at the LHC has heralded a new era in understanding the nature of electroweak symmetry breaking and possibly completing the standard model of particle physics. Since…
Search for light (within the mass range 84-200 GeV) doubly-charged Higgs bosons decaying into a pair of W-bosons has been deemed challenging using the conventional LHC searches with leptons, jets and missing transverse momentum in the final…
A weak-doublet with hypercharge $-3/2$ is one of only a handful of fermions which has a renormalisable interaction with Standard Model fields. This should make it worthy of attention, but it has thus far received little consideration in the…
The latest electroweak precision data are analyzed assuming the existence of the fourth generation of leptons ($N, E$) and quarks ($U, D$), which are not mixed with the known three generations. If all four new particles are heavier than $Z$…
We study rare four-body decays of the Z-boson involving at least one neutrino and one charged lepton. Large destructive interferences make these decays very sensitive to the Z couplings to neutrinos. As the identified charged leptons can…
We construct an $SU(2)_L\times SU(2)_R\times U(1)_{B-L}$ model with a Higgs sector that consists of a bidoublet and a doublet, and with a right-handed neutrino sector that includes one Dirac fermion and one Majorana fermion. This model…
In this work we assess the potential of discovering new physics by searching for lepton-flavour-violating (LFV) decays of the $Z$ boson, $Z\to \ell_i \ell_j$, at the proposed circular $e^+e^-$ colliders CEPC and FCC-ee. Both projects plan…
We study the Z'-> ggg decay in the context of a left-right symmetric gauge theory. We obtain a branching ratio BR(Z'-> ggg)=\Gamma(Z'->ggg)/ \Gamma(Z'-> q\bar{q})= (1.2-2.8) x 10^{-5} for m_{Z'}=(700-1500) GeV. We also study the…
We study the quantum properties of the Higgs-boson decays into four fermions via two vector bosons $(H\to VV^*\to 4f)$. In particular, we focus on the case of two different-flavour lepton pairs $(H\to ZZ^*\to \mu^+\mu^- e^+ e^-)$. We…
In some models of electro-weak interactions the W and Z bosons are considered composites, made up of spin-one-half subconstituents. In these models a spin zero counterpart of the W and Z boson naturally appears, whose higher mass can be…
The effects of an extra $Z'$ gauge boson with family nonuniversal fermion couplings on the rare top quark decay $t --> c $gamma$ are first examined in a model independent way and then in the minimal 331 model. It is found that the…
We study the LHC potential for discovering TeV-scale SU(2)_L 5-plet fermions introduced recently to explain small neutrino masses. We show that the Drell-Yan production and the decays of new exotic Sigma leptons are testable at the LHC.…
$Z^\prime$ boson as a new gauge boson has been proposed in many new physics models. The interactions of $Z^\prime$ coupling to fermions are detailed studied at the large hadron collider. A $Z^\prime$ with the mass of a few TeV has been…
A sequential fourth generation of quarks and leptons is allowed by precision electroweak constraints if the mass splitting between the heavy quarks is between 50 and 80 GeV. Although heavy quarks can be easily detected at the LHC, it is…
A search for heavy resonances that decay to tau lepton pairs is performed using proton-proton collisions at sqrt(s) = 13 TeV. The data were collected with the CMS detector at the CERN LHC and correspond to an integrated luminosity of 2.2…
The LHC discovery potential of heavy top partners decaying into a top quark and a $Z$ boson is studied in the trilepton channel at $\sqrt{s}=13$ TeV. The clean multilepton final state allows to strongly reduce the background contaminations…
We present an implementation of electroweak $ZZjj$ production in the POWHEG BOX V2 framework, an upgrade of the POWHEG BOX program which includes a number of new features that are particularly helpful for high-multiplicity processes. We…