Hsuan-Cheng Huang | Searcharxiv

arXiv2001

K+K- and KsKs Production in Two-Photon Collisions at Belle

The production of a kaon pair ($K^+ K^-$ and $K^0_S K^0_S$) in two-photon processes has been measured using the Belle detector at the electron-positron collider KEKB. We have obtained the invariant-mass distribution of the processes between 1.3 and 2.3 GeV. A broad bump structure around 1.7 GeV in the $K^0_S K^0_S$ channel is confirmed, while, in the $K^+ K^-$ channel, a bump structure is seen near 1.9 GeV. The angular distribution of the final-state kaons is analyzed to explore the spin(-helicity) structure in each invariant-mass region for the two processes. Contributions from existing and postulated resonances are discussed.

hep-ex↗

arXiv1994

Singlet Charge $2/3$ Quark hiding the Top: Tevatron and LEP Implications

If $c$ and $t$ quarks are strongly mixed with a weak singlet charge $2/3$ quark, $BR(t\to \ellν+ X)$ could be suppressed via the $t\to cH^0$ mode, thereby the top quark could still hide below $M_W$, whereas the heavy quark signal observed at the Tevatron is due to the dominantly singlet quark $Q$. This may occur without affecting the small $m_c$ value. Demanding $m_Q \simeq 175$ GeV and $m_t \ltap M_W$, we find that $BR(t\to \ellν+ X)$ cannot be too suppressed. The heavy quark $Q$ decays via $W,\ H$, and $Z$ bosons. The latter can lead to $b$-tagged $Z + 4$ jet events, while the strong $c$--$Q$ mixing is reflected in sizable $Q\to sW$ fraction. $Z\to t\bar c$ decay occurs at tree level and may be at the $10^{-3}$ order, leading to the signature of $Z\to \ellνb\bar c$, all isolated and with large $p_T$, at $10^{-5}$ order.

hep-ph↗