arXiv subjects

Chong Sheng Li

Publications and source records attributed to Chong Sheng Li.

118 records · Page 7Linked to original sources

arXiv1998

Supersymmetric QCD Parity Nonconservation in Top Quark Pairs at the Tevatron

In the supersymmetry (SUSY) models, because of the mass difference between the left- and right-top squarks, the supersymmetric QCD interactions can generate parity violating effects in the production of $ t \bar t$ pairs. We show that SUSY QCD radiative corrections to the parity violating asymmetry in the production rates of the left- and right-handed top quarks via the $q \bar q \ra t \bar t$ process can reach about 3% at the Fermilab Tevatron with $\sqrt{s}=2$ TeV. This could be observable with an integrated luminosity larger than $2 fb^{-1}$. We also show that in these models the SUSY QCD radiative corrections to the $t \bar t$ production rate are small unless gluinos are very light, of the order of 1 GeV.

hep-ph↗

arXiv1997

Supersymmetric QCD Corrections to Single Top Quark Production at the Fermilab Tevatron

We evaluate the supersymmetric QCD corrections to single top quark production via $q \bar q'\to t \bar b$ at the Fermilab Tevatron in the minimal supersymmetric model. We find that within the allowed range of squark and gluino masses the supersymmetric QCD corrections can enhance the cross section by a few percent. The combined effects of SUSY QCD, SUSY EW, and the Yukawa couplings can exceed 10% for the smallest allowed $\tanβ~ (\simeq 0.25)$ but are only a few percent for $\tanβ>1$.

hep-ph↗

arXiv1997

Supersymmetric Electroweak Parity Nonconservation in Top Quark Pair Production at the Fermilab Tevatron

We evaluate the supersymmetric (SUSY) electroweak corrections to the effect of parity nonconservation in $q {\bar q} \to t {\bar t}$ production at the Fermilab Tevatron predicted by the Minimal Supersymmetric Model (MSSM). We find that the parity nonconserving asymmetry from the SUSY electroweak and SUSY Yukawa loop corrections predicted by the minimal supergravity (mSUGRA) model and the MSSM models with scenarios motivated by current data is about one percent. It will be challenging to observe such a small asymmetry at the Tevatron with 10 fb^{-1} of luminosity. It could however be observable if both the top- and bottom-squarks are light and $\tan β$ is smaller than 1, though theses parameters are not favored by mSUGRA.

hep-ph↗

arXiv1996

Supersymmetric Electroweak Corrections to Single Top Quark Production at the Fermilab Tevatron

We have calculated the $O(α_{ew} M_t^2/M_W^2)$ supersymmetric electroweak corrections to single top quark production via $q\bar q' \to t\bar b$ at the Fermilab Tevatron in the minimal supersymmetric model. The supersymmetric electroweak corrections to the cross section are a few percent for $tan β> 1$, and can exceed 10% for $tanβ<1$. The combined effects of SUSY electroweak corrections and the Yukawa corrections can exceed 10% for favorable parameter values, which might be observable at a high-luminosity Tevatron.

hep-ph↗

arXiv1996

Yukawa Corrections to Single Top Quark Production at the Fermilab Tevatron in the Two-Higgs-Doublet Models

We calculate Yukawa corrections of order $α_{ew} M_t^2/M_W^2$ to single top quark production via $q \bar q'\rightarrow t \bar b$ at the Fermilab Tevatron in the two-Higgs-doublet models. In our calculation we also keep the terms proportional to $ M_b^2 \tan^2 β$ since their effects may become rather important for large $\tanβ$. The corrections can amount to more than a 15\% reduction in the production cross section relative to the tree level result in the general two-Higgs-doublet model, and a 10\% enhancement in the minimal supersymmetric model, which might be observable at a high-luminosity Tevatron.

hep-ph↗

arXiv1996

One-loop QCD Corrections to Top Quark Decay into a Neutralino and Light Stop

We calculate the one-loop QCD corrections to $t\rightarrow \tilde t_1 \tilde χ^0_j$ using dimensional reduction scheme, including QCD and supersymmetric QCD corrections. The analytic expressions for the corrections to the decay width are given, which can easily be extended to $t\rightarrow \tilde χ^+_j \tilde b_i $. The numerical results show that the correction amounts to more than a 10\% reduction in the partial width relative to the tree level result. We also compare the corrections in the no-mixing stop case with those in the mixing stop case.

hep-ph↗

arXiv1996

Yukawa corrections to top pair production in photon-photon collision

The $O(αm_t^2/m_W^2)$ Yukawa corrections to top pair production in photon-photon collision are calculated in the standard model (SM), the general two-Higgs-doublet model (2HDM) as well as the minimal supersymmetric model (MSSM). We found that the correction to the cross section can only reach a few percent in the SM, but can be quite significant ($>$10\%) in the 2HDM and MSSM for favorable parameter values, which may be observable at the high energy $e^+e^-$ colliders.

hep-ph↗

arXiv1996

Strong supersymmetric quantum effects on top quark production at the Fermilab Tevatron

The supersymmetric QCD corrections to top quark pair production by $q\bar q$ annihilation in $p\bar p$ collisions are calculated in the minimal supersymmetric model. We consider effects of the mixing of the scalar top quarks on the corrections to the total $t\bar t$ production cross section at the Fermilab Tevatron. We found that such correction is less sensitive to squark mass and gluino mass than in no-mixing case, and in both cases the corrections can exceed 10\% even if we consider the recent CDF limit on squark and gluino masses.

hep-ph↗

arXiv1996

Top-squark mixing effects in the supersymmetric electroweak corrections to top quark production at the Tevatron

Taking into account the mixing effects between left- and right-handed top-squarks, we calculate the genuine supersymmetric eletroweak correction to top quark production at the Tevatron in the minimal supersymmetric model. The analytic expressions of the corrections to both the parton level cross section and the total hadronic cross section are presented. Some numerical examples are also given to show the size of the corrections.

hep-ph↗

arXiv1996

Top Quark Decays into Heavy Quark Mesons

For top quark decays into heavy quark mesons $Υ$ and $\bar{B}_c^*$ , a complete calculation to the leading order both in QCD coupling constant $α_s$ and in $v$, the typical velocity of the heavy quarks inside the mesons, is performed. Relatons between the top quark mass and the decay branching ratios are studied. Comparion with the results which are obtained by using the quark frangmentation functions is also discussed. The branching ratios are consistent (within a factor of $2\sim 3 $) with that obtained using fragmentation functions at $m_t\sim 150$ GeV.

hep-ph↗