Related papers: Z' near the Z-pole
The present data on a number of observables in $b\to s\mu^+\mu^-$ processes manifest some tensions with the standard model (SM). Assuming that these anomalies have a new physics origin, we consider the possibility that a $Z'$ boson is…
$Z^\prime$ 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…
We present a measurement of the ZZ boson-pair production cross section in 1.96 TeV center-of-mass energy ppbar collisions. We reconstruct final states incorporating four charged leptons or two charged leptons and two neutrinos from the full…
We improve the theoretical predictions for rare $Z$-boson decays, $Z\to V\ell^+\ell^-$ ($\ell=e$ or $\mu$), where $V$ denotes a heavy vector quarkonium including $J/\Psi$, $\Psi (2S)$, and $\Upsilon (nS)$ with $n=1,2,3$. These processes are…
The associated production of $Z$ boson and a pair of new quarks at the Large Hadron Collider (LHC) is studied. The cross sections for both sequential fermions and vector-like fermions are presented. It is found that for sequential fermions…
We consider a neutrinophilic $U(1)$ extension of the Standard Model (SM) under which only a second Higgs doublet and SM singlet scalars and fermions are charged. The new gauge boson $Z'$ couples to SM minimally, generated by $Z-Z'$ mixing.…
The lightest Higgs scalar boson mass in supersymmetry can be raised significantly by extra vector-like quark and lepton supermultiplets with large Yukawa couplings but dominantly electroweak-singlet masses. I consider models of this type…
We investigate the phenomenology of the dark $Z$ boson, $Z_d$, which is associated with a new Abelian gauge symmetry and couples to the standard model particles via kinetic mixing $\varepsilon$ and mass mixing $\varepsilon_Z^{}$. We examine…
A search is reported for the pair production of a new quark, b', with at least one b' decaying to a Z boson and a bottom quark. The data, corresponding to 2.0 fb^-1 of integrated luminosity, were collected from pp collisions at sqrt(s) = 7…
Searching for heavy neutral gauge bosons Z', predicted in extensions of the Standard Model based on a U(1)' gauge symmetry, is one of the challenging objectives of the experiments carried out at the Large Hadron Collider. In this paper, we…
The first calculation of the next-to-leading-order electroweak corrections to Z-boson + jet hadroproduction including leptonic Z-boson decays is presented, i.e. to the production of a charged lepton--anti-lepton final state in association…
We consider the possibility that one extra $Z\equiv Z'$ exists with arbitrary mass and fermion couplings that do not violate (charged) lepton universality. We show that, in such a situation, a functional relationship is generated between…
Several constructions, of stringy origins or not, generate abelian gauge extensions of the Standard Model (SM). Even if the particles of the SM are not charged under this extra $U'(1)$, one cannot avoid the presence of a kinetic mixing…
To resolve the long-standing discrepancy between the precision measurement of bottom quark forward-backward asymmetry at LEP/SLC and the Standard Model prediction, we propose a novel method to probe the $Zb\bar{b}$ coupling by measuring the…
Improved predictions for the Z-boson decay width and the hadronic Z-peak cross-section within the Standard Model are presented, based on a complete calculation of electroweak two-loop corrections with closed fermion loops. Compared to…
A measurement of the production cross section for a top quark pair in association with a $Z$ boson ($t\bar{t}Z$) is presented in this PhD thesis. Final states with exactly three charged leptons (electrons or muons) are used, taking into…
We derive a method for a common treatment of Z' exchange, QED corrections, and weak loops. It is based on the form factor approach to the description of weak loop corrections to partial Z widths and cross sections. Problems connected with…
We investigate the capability of the NLC to indirectly determine both the mass as well as the couplings to leptons and $b$-quarks of a new neutral gauge boson below direct production threshold. By using data collected at several different…
We propose a new strategy to probe the $Z$ boson couplings to bottom and charm quarks at the LHC. In this work we mainly focus on the case of bottom quarks. Here, the $Z$ boson is produced in association with two $b$-jets and decays to…
Extracting constraints on kinetic mixing between a new $U(1)'$ gauge boson hiding under the Standard Model $Z$ boson resonance requires the formalism of non-Hermitian two-point correlation functions at 1-loop order. We derive…