arXiv subjects
Publications and source records attributed to Chao-Shang Huang.
We explore the discovery potential of the supersymmetric Higgs bosons through $bg$ channel at Tevatron and LHC. Compared with the process of $qq' \to WH$, this channel is more advantigeous to finding the supersymmetric Higgs bosons at Tevatron if $\tanβ$ is larger than ten.
We revisit the eleven dimension Planck scale, the physical scale of the eleventh dimension, the physical scale of Calabi-Yau manifold and coupling in hidden sector in M-theory on $S^1/Z_2$. And we discuss the reasonable bound on them. Considering F-term of dilaton and moduli SUSY breaking and choosing two repersentative points which correspond to scalar quasi-massless scenario and dilaton dominant SUSY breaking scenario respectively, we analyze experimental constraints to the parameter space. The sparticle spectrum and some phenomenological predictions are also given.
We investigate the flavor changing neutral current bsV(V=$γ$,Z) couplings in the production vertex for the process $e^+e^-\to b\bar s or \bar b s$ in the standard model. The precise calculations keeping all quark masses non-zero are carried out. Production cross sections are found to be the order of $10^{-3}$ fb at LEP II and the order of $10^{-1}$ fb when center-of-mass energy is near the mass of neutral gauge boson Z.
The flavor changing neutral current tcV (V=γ,Z) couplings in the production vertex for the process $e^+e^-\to t\bar c$ or $\bar t c$ in the standard model are investigated. The precise calculations keeping all quark masses non-zero are carried out. The total production cross section is found to be $1.84 \times 10^{-9}$ fb at $\sqrt s =200 GeV$ and $0.572 \times 10^{-9}$ fb at $\sqrt s =500 GeV$ respectively. The result is much smaller than that given in ref. \cite{clwy} by a factor of $10^{-5}$.
The $Λ_b \to p$ semileptonic decay is analyzed by using QCD sum rules within the framework of heavy quark effective theory. The Isgur-Wise function of $Λ_b \to p l \barν$ has been calculated. The decay width is given.
It is shown that in supersymmetric models (SUSYMs) the large supersymmetric contributions to $B \to X_sμ^{+}μ^{-}$ come from the Feynman diagrams which consist of exchanging neutral Higgs bosons (NHBs) and the chargino-stop loop and are proportional to $m_b m_μ$tan$^3β/m_{h}^2$ when tan$β$ is large and the mass of the lightest neutral Higgs boson m$_h$ is not too large (say, less than 150 Gev). Numerical results show that the branching ratios of $B \to X_sμ^{+}μ^{-}$ can be enhanced by more than 100% compared to the standard model (SM) and the backward-forward asymmetry of lepton is significantly different from that in SM when tan$β\geq 30$.
Non-leading contribution to the pion electromagnetic form factor which comes from the pion twist-3 wave function is analyzed in the modified hard scattering approach (MHSA) proposed by Li and Sterman. This contribution is enhanced significantly due to bound state effect (the twist-3 wave function is independent of the fractional momentum carried by the parton and has a large factor $\sim m_π^2/m_0$ with $m_π$ being the pion meson mass and $m_0$ being the mean u- and d-quark masses). Consequently, although it is suppressed by the factor $1/Q^2$, the twist-3 contribution is comparable with and even larger than the leading twist (twist-2) contribution at intermediate energy region of $Q^2$ being $2 \sim 40 {GeV}^2$.
We perform a detailed study of the inclusive branching ratio and the forward-backward asymmetry of the rare B decay process $B \longrightarrow X_{s} τ^{+} τ^{-}$ in the flipped SU(5) model, a predictive model which has only two free parameters, plus the sign of the higgs mixing mass $μ$, to describe mass spectrum and mixings of about 30 sparticles. In contrast to other works dealing with such a topic, our study has included the contributions of the neutral higgs bosons through penguin diagrams to this process under the context of supersymmetry. In some regions of the parameter space, due to the substantial enhancement effects coming from supersymmetry, these contributions become quite significant and could make the flavor change process $B \longrightarrow X_{s} τ^{+} τ^{-}$ a microscope to probe the regions of large tan$β$ and a window to gain an insight into new physics beyond the standard model(SM).
The inclusive rate and $τ$ spectrum for a polarized $Λ_b$ -baryon to decay to charm hadronic final states and leptons $τν$ in the SM and a two-Higgs doublet model are computed.The $O(α_s)$ QCD corrections to $τ$ spectrum in the two-Higgs model are also given.
The inclusive rate and forward-backward asymmetry of dilepton angular distribution for a B-meson to decay to strange hadronic final states and a $τ^+τ^-$ pair in a two Higgs doublet model are computed. In particular, contributions of neutral Higgs bosons to the decay are included. QCD corrections to the effective Hamiltonian for $B\rightarrow X_sτ^+τ^-$ are calculated using the leading logarithmic approximation.