Related papers: Composite Scalars at LEP: Constraining Technicolor…
We calculate the new contributions to the rare decays $K^+ \to \pi^+ \nu \bar \nu$, $K_L \to \pi^0 \nu \bar \nu$ and $K_L \to \mu^+ \mu^-$ from new $Z^0$-penguin and box diagrams induced by the unit-charged scalars $(\tilde{\pi}^\pm,…
In this paper we assume the Higgs is an elementary scalar, and study how new physics could affect its couplings to electroweak gauge bosons. Adding LHC data to LEP data provides new, more stringent limits, particularly when the Higgs to two…
We present a new class of constraints to the lepton-family number and R-parity violating couplings from muonium conversion, $\mu^{-} + {_{22}^{48}} Ti \to e^{-} + {_{22}^{48}} Ti$, a class of tau decays, $\tau \to l +$ (light meson) with…
The recent LEP data for gauge coupling constants constrain many grand unified models. In this paper, we study several possibilities for unification of gauge coupling constants. Without an intermediate mass scale, the minimal supersymmetric…
In the standard model production of on-shell Z boson at a photon collider (or Z decays into $\gamma\gamma$) is strictly forbidden by angular momentum conservation and Bose statistics (the Yang's Theorem). In the standard model with…
We investigate the production and the decays of pseudo-Goldstone bosons (PGBs) predicted by technicolor theories with the GIM mechanism (TC-GIM). The TC-GIM models contain exotic fermion families that do not interact under weak $SU(2)$, but…
The properties of the pseudoscalar Goldstone bosons in the color-flavor locked phase at moderate densities are studied within a model of the Nambu--Jona-Lasinio type. The Goldstone bosons are constructed explicitly by solving the…
We revisit a class of Z' explanations of the anomalies found by the LHCb collaboration in $B$ decays, and show that the scenario is tightly constrained by a combination of constraints: (i) LHC searches for di-muon resonances, (ii)…
Using the updated form factors within the light-cone QCD sum rule approach, we calculate the new physics contributions to rare semileptonic $\bar{B}_s \to \phi\mu^+\mu^-, \phi \tau^+\tau^-$ decays from the new particles appearing in the…
We show that LEPII will either discover charginos and neutralinos, or enable a very stringent upper limit to be placed on $\tan \beta$ as a function of the gluino mass. The only assumption we make is the existence of some unified model…
New light pseudoscalars, such as axion-like particles, appear in many well-motivated extensions of the Standard Model and provide an exciting target for present and future experiments. We study the experimental sensitivity for such…
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…
Neutrino experiments lie at the edge of the intensity frontier and therefore can be exploited to search for new light particles weakly coupled to the visible sector. In this work we derive new constraints on axion-like particles (ALPs)…
We investigate the minimal $U(1)_{L_\mu-L_\tau}$ model with extra heavy vector-like leptons or charged scalars. By studying the kinetic mixing between $U(1)_{L_\mu-L_\tau}$ gauge boson $Z^\prime$ and standard model photon, which is absent…
We show that the accumulated LEP-II data taken at $\sqrt{s} =$ 130 to 206 GeV can establish more restrictive bounds on doubly charged bileptons couplings and masses than any other experiment so far. We also analyze the discovery potential…
Near-threshold production of boson pairs is considered within the framework of the model of unstable particles with smeared mass. We describe the principal aspects of the model and consider the strategy of calculations including the…
We analyze the constraints on possible anomalous contributions to the $W^+W^-Z$ vertex coming from non-universal radiative corrections to the $Z \rightarrow b \bar{b}$ width. We parametrize these corrections in terms of $\epsilon_b$ and use…
Axionlike particles (ALPs) are hypothetical light (sub-eV) bosons predicted in some extensions of the Standard Model of particle physics. In astrophysical environments comprising high-energy gamma rays and turbulent magnetic fields, the…
We have calculated the composite (pseudo) scalar contributions to the anomalous magnetic moment of muons in models of walking technicolor. By the axial or scale anomaly the light scalars such as techni-dilaton, techni-pions or techni-eta…
Near-threshold production of neutral boson pairs is considered within the framework of the model of unstable particles with smeared mass. The results of calculations are in good agreement with LEP II data and Monte-Carlo simulations.