Related papers: S-matrix approach to the Z resonance
The past ten years of physics with e+e- colliding experiments at LEP and SLAC have shown the success of these experiments on not only impressively proving the theoretical predictions of the Standard Model (SM), but also to help provide…
An S-Matrix ansatz is used to determine the mass and width of the Z boson, as well as the contributions of gamma/Z interference and Z boson exchange to fermion-pair production. For this purpose we use hadron and lepton-pair production cross…
The FCC-ee offers powerful opportunities for direct or indirect evidence for physics beyond the Standard Model, via a combination of high precision measurements and searches for forbidden and rare processes and feebly coupled particles. A…
The Z line shape is measured at LEP/CERN with an accuracy at the per mille level. Usually it is described in the Standard Model of electroweak interactions with account of quantum corrections. Alternatively, one may attempt an S-matrix…
In this article, we calculate the $S$-matrix elements for the process $e^{+} e^{-}\rightarrow t \bar{t}$ mediated by SM photon, $Z$ boson and an additional $Z^{'}$ boson indicating the contribution from new physics. We calculate the…
We explore the potential of the $e^+ e^-$ colliders to discover dark matter and determine its properties such as mass and the spin. For this purpose we study spin zero and spin one-half cases of dark matter, $D$ which belongs to $SU(2)$…
The first part of the physics programme of the integrated FCC (Future Circular Colliders) proposal includes measurements of Standard Model processes in $e^+e^-$ collisions (FCC-ee) with an unprecedented precision. In particular, the…
ZFITTER is a Fortran program for the calculation of fermion pair production and radiative corrections at high energy e+e- colliders; it is also suitable for other applications where electroweak radiative corrections appear. ZFITTER is based…
We investigate the pair production process $e^+e^- \to H^+H^-$ in the framework of the scotogenic model. The production mechanism receives contributions at tree level from photon and $Z$-boson exchange, as well as from $t$-channel exchange…
We review briefly the properties of a mixture of mutually interacting bosons (bound electron pairs) and itinerant fermions on a lattice (the boson-fermion model). The calculations of the superconducting phase transition temperature…
We examine the possibility to detect new SM-neutral vector bosons ($Z'$) that couple exclusively to leptons in the electron-positron mode of the Future Circular Collider (FCC-ee). Focusing on the $Z'$ production with a radiated photon…
The physics program accessible in $e^+e^-$ collisions at the Future Circular Collider (FCC-ee) is summarized. The FCC-ee aims at collecting multi-ab$^{-1}$ integrated luminosities in $e^+e^-$ at $\sqrt{s}$ = 90, 160, 240, and 350 GeV,…
We consider the possibility of new physics giving rise to effective interactions of the form $e^+e^-Hf \bar f$, where $f$ represents a charged lepton $\ell$ or a (light) quark $q$, and $H$ the recently discovered Higgs boson. Such vertices…
We investigate the forward-backward asymmetries in the pair production of fourth family fermions through the new Z' interactions in the e+e- collisions. The Z' boson having family universal couplings can contribute to the pair production of…
We compute several total and differential cross sections relevant to top and WWZ physics at future $e^+e^-$ colliders taking into account the full set of Feynman diagrams for six fermion final states. We also include in our calculations…
Because of a luminosity of up to five orders of magnitude larger than at LEP, electroweak precision measurements at the FCC-ee -- the Future Circular Collider with electron-positron beams -- would provide improvements by orders of magnitude…
SMATASY is an interface for the ZFITTER package and may be used for the model independent description of the Z resonance at LEP 1 and SLC. It allows the determination of the Z mass and width and its resonance shape parameters r and j for…
A future $e^+e^-$ collider could run at the Z-pole to perform important electroweak (EW) precision measurements, while such a run may not be viable for a future muon collider. This however can be compensated by the measurements of other EW…
We explore the mono-$Z$ signature for dark matter searches at future high energy $e^+e^-$ colliders. In the context of effective field theory, we consider two kinds of contact operators describing dark matter interactions with electroweak…
The associated production of a Higgs boson with a $Z$ boson in the collisions of electron and positron beams at Future Circular Collider (FCC-ee) have been studied. Here, the $Z$ boson decays into dileptons, while the Higgs boson decays to…