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Hong-Yi Zhou

Publications and source records attributed to Hong-Yi Zhou.

15 recordsLinked to original sources
arXiv2000

Pseudo-Goldstone Boson Effects in Top-Antitop Productions at High Energy Hadron Colliders and Testing Technicolor Models

We study the top quark pair production process p+p(anti-p)-->top+antitop in various kinds of technicolor (TC) models at the Fermilab Tevatron Run II and the CERN LHC. The s-channel neutral pseudo-Goldstone bosons (PGB's) contribute dominately to the production amplitudes from its coupling to the gluons through the triangle loops of techniquarks and the top quark. Cross sections in different TC models with s-channel PGB contributions are calculated. It is shown that the PGB effects can be experimentally tested and different TC models under consideration can be distinguished at the LHC. Therefore, the p+p-->top+antitop process at the LHC provides feasible tests of the TC models.

hep-ph↗
arXiv1998

Testing Technicolor Models via Top Quark Pair Production in High Energy Photon Collisions

Pseudo-Goldstone boson contributions to $t\bar{t}$ production rates in technicolor models with and without topcolor at the $\sqrt{s}=0.5 and 1.5$ TeV photon colliders and hadron colliders are reviewed. For reasonable ranges of the parameters, the contributions are large enough to be experimentally observable. Models with topcolor, without topcolor and the MSSM with $\tanβ\geq 1$ can be experimentally distinguished.

hep-ph↗
arXiv1998

Determining Top Quark CP Violating Dipole Couplings from $e^+e^-\to t\bar t$

We show how to determine the electric and weak dipole moments of the top quark simultaneously and independently from $e^+e^-\to t\bar t$ at $\sqrt{s}=500$ GeV NLC. To obtain the best accuracies with which the dipole moments can be measured, we apply the optimal observables to extract the CP violating effects and consider only purely hadronic, hadronic-leptonic final state events. Results with left- and right- handed longitudinal polarized as well as unpolarized electron beams are given. We find that with $50fb^{-1}$ integrated luminosity, the dipole moments can be measured to the accuracy of $10^{-18}~e~cm$.

hep-ph↗
arXiv1998

An Implication of Ether Drift

The experimental results of the two-photon absorption(TPA) and Mössbauer-rotor(MR) for testing the isotropy of the speed of light are explained in an ether drift model with a drift velocity of $\sim 10^{-3}c$. Further tests of the ether drift assumption are suggested.

gr-qc↗
arXiv1998

Supersymmetric Electroweak Corrections to Top Quark Production at LHC

The $αm_t^2/m_W^2$ order supersymmetric electroweak corrections arising from loops of chargino, neutralino, and squark to top quark pair production by $gg$ fusion at LHC are calculated in the minimal supersymmetric model. We found that the corrections amount about a few percent.

hep-ph↗
arXiv1998

CP Violation in Top Quark Pair Production at Hadron Colliders

CP violating effects in top quark pair production at the future 2 TeV $p\bar p$ Tevatron and 14 TeV $pp$ LHC colliders are investigated. We study three kinds of CP violating sources:the supersymmetric CP-odd phase of the stop trilinear soft breaking term: $arg(A_t)$, the CP-odd parameter in two-Higgs doublet extensions of the standard model(2HDM), and the model-independent top quark chromoelectric dipole moment(CEDM), respectively. Optimal observables as well as simple observables are used. We find that it is possible to observe CP violating effects from $arg(A_t)$ in top quark pair production at the 2 TeV Tevatron with $\sim 30fb^{-1}$ integrated luminosity when $m_{\tilde{g}}\sim 200$ GeV. If the experimental systematic errors are sufficient small, the LHC with $\sim 150fb^{-1}$ can put a limit of order $10^{-1}$ on the phase $arg(A_t)$ and the CP-odd parameter in 2HDM by using optimal observables. The CEDM of the top quark can be measured to an accuracy of $10^{-18} cm g_s$ at the Tevatron and few $\times 10^{-20} cm g_s$ at the LHC.

hep-ph↗
arXiv1998

Signatures of the light gluino in the top quark production

If a light gluino, with a mass of the order of GeV, exists in the minimal supersymmetric extension of the Standard Model, then it can contribute to the production rate of the top quark pairs at hadron colliders via the process gluino + gluino --> t + tbar. Because the top quark is heavy, the masses of the superpartners of the left-handed and right-handed top quarks can be very different such that a parity-violating observable can be induced at the tree level. We discuss the phenomenology of this parity violating asymmetry at the CERN Large Hadron Collider.

hep-ph↗
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

Testing Technicolor Models in Top Quark Pair Production at High Energy Photon Colliders

We study pseudo-Goldstone boson corrections to top quark pair production rates in technicolor models with and without topcolor at the E=0.5 teV and 1.5 TeV photon colliders. We find that, for reasonable ranges of the parameters, the corrections are large enough to be observable, and the corrections in models with topcolor are considerably larger than those in models without topcolor, and they are all significantly larger than the corresponding corrections in the minimal supersymmetric standard model (MSSM) with tan(beta) of the order of 1. So that the two kinds of technicolor models and the MSSM with tan(beta) of the order of 1 can be experimentally distinguished.

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↗
arXiv1996

t anti-t Production Rates at the Tevatron and the LHC in Topcolor- Assisted Multiscale Technicolor Models

We study the contributions of the neutral pseudo Goldstone bosons (technipions and top-pions) to the t anti-t production cross sections at the Tevatron and the LHC in topcolor-assisted multiscale technicolor (TOPCMTC) models via the gluon-gluon fusion process from the loop-level couplings between the pseudo Goldstone bosons and the gluons. The MRS set A' parton distributions are used in the calculation. It is shown that the new CDF datum on the t anti-t production cross section gives constraints on the parameters in the TOPCMTC models. With reasonable values of the parameters in TOPCMTC models, the cross section at the Tevatron is larger than that predicted by the standard model, and is consistent with the new CDF data. The enhancement of the cross section and the resonance peaks at the LHC are more significant, so that it is testable in future experiments.

hep-ph↗
arXiv1996

Supersymmetric QCD Corrections to Top Quark Pair Production in Photon-Photon Collision

Supersymmetric QCD corrections to top quark pair production by photon fusion are calculated in the minimal supersymmetric standard model taking into account of the effects of stops in the corrections to the total cross-section of t anti-t production at the future electron-positron linear collider. We find that the relative correction can be a few percent for reasonable values of the parameters.

hep-ph↗
arXiv1995

Detecting the intermediate-mass Higgs boson through the associate production channel pp --> t + anti-t + H + X

We examine the detection of the intermediate-mass Higgs boson (IMH) at LHC through the associate production channel pp-->t+(anti-t)+H+X-->l+photon+ photon+X'. It is shown that by applying kinematic cuts or b-tagging on the final state jets, the main backgrounds of W(-->l+nu)+photon+photon+(n-jet) can be reduced substantially without significant loss of signals. It is possible to detect the Higgs boson at LHC through the pp-->t+(anti-t)+H+X channel using a modest photon detector with mass resolution of about 3% of the photon pair invariant mass.

hep-ph↗