Related papers: Probing the Scalar Sector in $e^+ e^- \to Z \phi$
We show that $\phi$ radiative decays into scalar mesons [$f_0$(975), $a_0$(980)$\equiv S$] can provide important clues on the internal structures of these mesons. Radiative decay widths vary widely: $B.R.=10^{-4}-10^{-6}$ depending on the…
We present a general framework for the model-independent decomposition of the fully differential cross section of the reactions e+e- -> gamma* -> (pi0 pi0 gamma) and e+e- -> gamma* -> (pi0 eta gamma), which can provide important information…
We discuss triple $Z'$ boson signatures via the decay chain of $Z \to Z' \phi \to Z' Z' Z'$, with a new light scalar $\phi$, at future Z factories such as CEPC and FCC-ee. These new bosons $\phi$ and $Z'$ naturally appear in models with a…
Exploring correlations between the CP asymmetries of $B^0_d\to\pi^0K_{\rm S}$ following from an isospin relation, we uncover new tensions with the Standard Model in data for neutral $B\to\pi K$ decays. Should this intriguing picture…
In this report I surveyed physics potential of the gamma-gamma option of a Linear e+e- Collider with the following questions in mind: What new discovery can be expected at a gamma-gamma collider in addition to what will be learned at its…
When a top quark is highly boosted, the $W$ boson from its decay has a substantial linear polarization that results in a $\cos 2\phi$ azimuthal angular correlation among the top decay products. We show that this correlation can be measured…
The model independent measurement of the absolute ZH cross section of the Higgsstrahlung process e+e- -> ZH is an unique measurement at the ILC indispensable for measuring the Higgs couplings and their deviations from the Standard Model in…
With $\mu\to e\gamma$ decay forbidden by multiplicative lepton number conservation, we study muonium--antimuonium transitions induced by neutral scalar bosons. Pseudoscalars do not induce conversion for triplet muonium, while for singlet…
We consider indirect searches for additional neutral vector bosons in $e^+e^-$ and $e^-e^-$ collisions, and compare these two linear collider modes with similar analysis procedures and assumptions. Discovery limits and resolving power are…
Forward-backward asymmetry in the process $e^+ e^- \rightarrow \gamma Z$ is proposed as a test for $CP$--violating anomalous $\gamma \gamma Z$ and $ \gamma Z Z$ couplings. Longitudinally polarized electron beams may be used to disentangle…
We demonstrate that the process $e^+e^-\to t\anti t h$ at the NLC provides a powerful tool for extracting the $t\anti t$ (Yukawa) couplings of the $\h$. In combination with the $\epem\to Z\h$ process, an accurate determination of the $ZZ$…
Neutrino self-interaction with a larger ``Fermi constant'' is often resorted to for understanding various puzzles of our universe. We point out that a light, neutrinophilic scalar particle $\phi$ through radiative correction leads to an…
We study the line shapes of radiative $\phi$-decays with a direct coupling of the $\phi$ meson to the $f_{0}(980)$ and $a_{0}(980)$ scalar mesons. The latter couple via derivative interactions to $\pi_0 \pi_0$ and $\pi_0 \eta$,…
We study phenomenological consequences of the Standard Model extension by the new spin-1 chiral fields with the internal quantum numbers of the electroweak Higgs doublets. There are at least three different classes of theories, all…
We review the decay properties and production mechanisms of the Standard-Model Higgs boson at a future e^+e^- linear collider with special emphasis on the influence of quantum corrections. We also discuss how its quantum numbers and…
The pure penguin process $B\to \phi K^*$ is one of the most important probes of physics beyond the Standard Model. Recently BaBar and Belle have measured the unexpectedly large transverse polarization in the decays $B\to \phi K^*$, which…
We compute the one-loop corrections to $\sigma(e^+ e^- \to Z h)$ arising from representative extended Standard Model scalar sector scenarios. According to the new scalar $\mathrm{SU(2)_L}$ representations, we consider the inert doublet,…
The scalar contributions to the radiative decay $\phi\to K^0\bar K^0\gamma$ are studied within the framework of the Linear Sigma Model. Theoretical predictions for the associated subprocesses $\phi\to f_0\gamma$ and $\phi\to a_0\gamma$ as…
The phenomenological constraints on extra neutral gauge bosons at present and at future colliders are reviewed. Special attention is paid to the influence of radiative corrections, systematic errors, and kinematic cuts on the Z'…
We study the production of Higgs boson (phi) via the e^{-}e^{+}--> e^{-}e^{+} phi process at a future International Linear Collider (ILC) with sqrt{S}=1 TeV. At this energy the ZZ-fusion rate, as predicted by the Standard Model, dominates…