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We undertake a phenomenological study of the extra neutral Z' boson in the Minimal Quiver Standard Model and discuss limits on the model's parameters from previous precision electroweak experiments, as well as detection prospects at the…
We present a phenomenological study of the discovery potential at the FCC-hh for a new heavy neutral vector boson, Z', predicted by the $U(1)_{B-L}$ gauge symmetry. Focusing on the parameter space currently not excluded by Large Hadron…
We propose to probe the electroweak symmetry breaking sector by measuring the effective couplings of the top quark to gauge bosons. Using precision LEP data, we constrain the non--universal couplings of t-t-Z and t-b-W, parameterized by…
This note presents a combination of published and preliminary electroweak results from the four LEP collaborations ALEPH, DELPHI, L3 and OPAL based on electron-positron collision data taken at centre-of-mass energies above the Z-pole, $130…
An updated fit to the precision electroweak data and to the direct measurement of the top quark mass $m_t$ provides significant constraints on $m_t$ and on the Higgs boson mass $M_H$: $m_t/\text{GeV}=172\pm 6$ and…
The discovery of a new neutral gauge boson, $Z'$, could provide the first concrete evidence of physics beyond the standard model. We explore how nuclear weak charge measurements in atomic parity violation (APV) experiments can be used to…
We propose a set of precision muon-related observables that serve as a tool to constrain new physics models. Using LEP's precision measurements on the $Z$-boson pole, we derive bounds on the new physics quantum contributions to the decay $Z…
The parity violation parameters $A_b$ and $A_c$ of the $Zb{\bar b}$ and $Zc\bar{c}$ couplings have been measured directly, using the polar angle dependence of the polarized cross sections at the $Z^0$ pole. Bottom and charmed hadrons were…
For the envisioned high precision measurement of the W boson mass at the Tevatron and LHC it is crucial that the theoretical predictions for the W and Z production processes are under control. We briefly summarize the status of the…
In view of the latest experimental results recently released by the ATOMKI collaboration, we critically re-examine the possible theoretical interpretation of the observed anomalies in terms of a new BSM boson $X$ with mass $\sim17\;$MeV. To…
We survey the implications for new physics of the discrepancy between the LEP measurement of $R_b$ and its Standard Model prediction. Two broad classes of models are considered: ($i$) those in which new $Z\bbar b$ couplings arise at tree…
We examine the capability of the NLC to determine the mass as well as the couplings to leptons and $b$-quarks of a new neutral gauge boson below production threshold. By using data collected at several different values of $\sqrt s$, we…
We present Standard Model predictions for the complete set of phenomenologically relevant electroweak precision pseudo-observables related to the Z-boson: the leptonic and bottom-quark effective weak mixing angles $\sin^2\theta_{\rm…
We consider one of the most significant deviations from the Standard Model: the forward-backward asymmetry of the b-quark measured at leptonic colliders. We investigate the possibility to solve this discrepancy by introducing new physics at…
A composite model of fermions is proposed to explain the "anomaly" in $Z \rightarrow b {\bar b}$ and, to a lesser extent, in $Z \rightarrow c {\bar c}$. It contains a {\em nonsequential} fourth family whose mass of one member (the charge…
A search for Z boson decays to pairs of b-quark jets has been performed in the full dataset collected with the CDF detector at the Tevatron proton-antiproton collider. After the selection of a pure sample of bb events by means of the…
The forward-backward asymmetry measurement in top-pair production at the Tevatron is about $2\sigma$ from the Standard Model prediction. We propose an asymmetric left-right model, which includes a $W'$ boson with a right-handed coupling of…
Measurements of $b \rightarrow s \mu^+ \mu^-$ transitions indicate that there may be a new physics field coupling to di-muon pairs associated with the $b$ to $s$ flavour transition. Including the 2022 LHCb reanalysis of $R_K$ and…
In canonical left-right symmetric models the lower mass bounds on the charged gauge bosons are in the ballpark of $3-4$ TeV, resulting into much stronger limits on the neutral gauge boson $Z_R$, making its production unreachable at the LHC.…
Recent $b\to s\ell\ell$ anomalies may imply the existence of a new $Z'$ boson with left-handed $Z'bs$ and $Z'\mu\mu$ couplings. Such a $Z'$ may be directly observed at LHC via $b \bar s \to Z' \to \mu^+\mu^-$, and its relevance to $b\to…