arXiv subjects

Chongxing Yue

Publications and source records attributed to Chongxing Yue.

35 records · Page 2Linked to original sources

arXiv2002

The study of a flavor-changing neutral toppion production process $e^+e^-\to t\bar{c}Π_t^0$

We have studied a flavor-changing toppion production process $e^{+}e^{-}\to t\bar{c}Π^{0}_{t}$ in the topcolor-assisted technicolor(TC2) model. The studies show that, with high centre of mass energy in TESLA collider, the production cross section of $e^{+}e^{-}\to t\bar{c}Π^{0}_{t}$ is at the order of magnitude 0.1 fb in most parameter regions of TC2 model and a few tens events of toppion can be produced each year. The resonance effect can enhance the cross section to a few fb when toppion mass is small. With clean background, the toppion events can possibly be detected at TESLA collider. On the other hand, we find that there exists a narrow peak near $m_t-m_c$ in the toppion-charm invariant mass distribution which could be clearly detected. Therefore, such a toppion production process $e^{+}e^{-}\to t\bar{c}Π^{0}_{t}$ provides a unique chance to detect toppion events and test the TC2 model.

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arXiv2002

Lepton flavor violating $Z\to l_il_j$ in flavor-universal topcolor-assisted technicolor

In the context of flavor-universal topcolor-assisted technicolor (TC2) models, we calculate the lepton flavor violating (LFV) $Z\to l_il_j$ decays. We find that the extra U(1) gauge boson $Z^{\prime}$ can give significant contributions to these LFV processes. With reasonable values of the parameters, the branching ratios of the processes $Z\to τμ$ and $Z\to τe$ can approach the experimental upper limits. The indirect bound on the process $Z\to μe$ can give a severe constraint on the flavor-universal TC2 models.

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arXiv2002

The dynamical models and the $Z \to b \bar{b}$ asymmetry}

Motivated by the $3.2σ(1.4σ)$ deviations between the recent experimental value for $A_{FB}^{b}(R_{b})$ and the standard model(SM) prediction, we examine the effect of new physics(NP) on the $Zb \bar{b}$ couplings $g_L^b$ and $g_R^b$. First we focus our attention on the dynamical models. Then, using effective lagrangean techniques, we discuss the corrections of NP to $g_L^b$ and $g_R^b$. We find some kinds of NP might explain the recently experimental data about $R_b$ and $A_{FB}^b$. However, the free parameters of these kinds of NP must be severely constrained.

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arXiv2002

Top quark associated production of the neutral top-pion at high energy $e^{+}e^{-}$ colliders

In the context of topcolor-assisted technicolor (TC2) models, we calculate the associated production of the neutral top-pion $π_{t}^{0}$ with a pair of top quarks via the process $e^{+}e^{-}\longrightarrow t\bar{t}π_{t}^{0}$. We find that the production cross section is larger than that of the process $ e^{+}e^{-}\longrightarrow t\bar{t}H$ both in the standard model (SM) and in the minimal supersymmetric SM. With reasonable values of the parameters in TC2 models, the cross section can reach $20fb$. The neutral top-pion $π_{t}^{0}$ may be direct observed via this process.

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arXiv2001

Signatures of the neutral top-pion in $eγ$ collisions

We calculate the contributions of the neutral top-pion $π_{t}^0$ to the process $e^-γ\to e^-\bar{t}c$ in the framework of topcolor-assisted technicolor(TC2) models and discuss the possible of detecting $π_t^0$ at the high energy linear $e^+e^-$ collider(LC). Our results show that $π_t^0$ can give significant contributions to this process. With reasonable values of the parameters in TC2 models, the cross section $σ$ can reach 0.19 fb which may be detected at the $eγ$ collisions based on the future LC experiments.

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arXiv2001

The process $e^{+}e^{-}\to \bar{t}c$ in topcolor-assisted technicolor models

We consider the flavor changing neutral current(FCNC) process $e^{+}e^{-}\to\bar{t}c$(or $t\bar{c}$) in the context of topcolor-assisted technicolor(TC2) models. We find that the contributions of charged scalars (technipions and top-pions) and topcolor gauge bosons are negligibly small. The neutral scalars (top-pion $π_{t}^{0}$ and top-Higgs $h_{t}^{0}$) can give significant contributions to this process. With reasonable values of the parameters in TC2 models, there will be several tens of the observable $\bar{t}c$ events to be generated in the future $e^{+}e^{-}$ linear colliders.

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arXiv2001

Lepton-Flavor Violating Processes $l_{i}\to l_{j}γ$ in Topcolor Assisted Technicolor Models

We consider the lepton-flavor violating(LFV) processes $l_{i}\to l_{j}γ$ in the framework of topcolor assisted technicolor(TC2) models. We find that the new gauge boson $Z^{\prime}$ predicted by TC2 models can give significantly contributions to these processes via the flavor changing couplings. The present experimental bound on the LFV process $μ\to eγ$ gives severe constraints on the TC2 models. In the case that the $Z^{\prime}$ mass $M_{Z}$ is consistent with other experimental constraints, we obtain constraints on the lepton mixing factors $K_{τμ}$ and $K_{τe}$. The future LFV experiments will be probe of the TC2 models.

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arXiv2001

The rare top decay $t\to c g$ in topcolor assisted technicolor models

In the framework of topcolor-assisted technicolor(TC2) models, we calculate the contributions of flavor changing scalar couplings involved the neutral top-pion $π_{t}^{0}$ and top-Higgs $h_{t}^{0}$ to the branching ratio $B_{r}(t\longrightarrow cg)$. We find that the value of $B_{r}(t\longrightarrow cg)$ can reach $ 1\times10^{-3}$ with reasonable values of the parameters in TC2 models, which may be testable in the future experiments.

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arXiv2001

Topcolor assisted technicolor models and muon anomalous magnetic moment

We discuss and estimate the contributions of the new particles predicted by topcolor assisted technicolor(TC2) models to the muon anomalous magnetic moment $a_μ$. Our results show that the contributions of Pseudo Goldstone bosons are very small which can be safely ignored. The main contributions come from the ETC gauge boson $x_μ$ and topcolor gauge boson $Z^{\prime}$. If we demand that the mass of $Z^{\prime}$ is consistent with other experimental constrains, its contributions are smaller than that of $x_μ$. With reasonable values of the parameters in TC2 models, the observed BNL results for $a_μ$ could be explained.

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arXiv2001

Detecting top-Higgs at high energy $e^{+}e^{-}$ colliders

We calculate the contributions of the top-Higgs $h_{t}^{0}$ predicted by topcolor assisted technicolor(TC2) models to $e^{+}e^{-}\longrightarrow \overline{t}c\overlineν_{e}ν_{e}$ and compare the results with the contributions of $h^{0}_{t}$ to the processes $e^{+}e^{-}\longrightarrow Z h^{0}_{t}\longrightarrow Z\overline{t}c$ and $e^+e^-\longrightarrow γh^{0}_{t} \longrightarrow γ\overline{t}c$. We find that $e^{+}e^{-} \longrightarrow\overline{t}c\overlineν_{e}ν_{e}$ is very sensitive to $h^{0}_{t}$, which can be easy detected via this process at high-energy $e^{+}e^{-}$ collider(LC) experiments with $\sqrt{s}\geq 500$ $GeV$, as long as its mass below the $\overline{t}t$ threshold. The process $e^{+}e^{-} \longrightarrow γ\overline{t}c$ also can be used to detect $h^{0}_{t}$ at LC experiments.

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arXiv2001

The flavor-changing rare top decays $t\to c V V$ in topcolor-assisted technicolor theory

In the framework of topcolor-assisted technicolor (TC2) theory, we calculate the contributions of the scalars(the neutral top-pion $π_{t}^{0}$ and the top-Higgs $h_{t}^{0}$) to the flavor-changing rare top decays $t\to c V V$(V= W, g, $γ$ or Z). Our results show that $h_{t}^{0}$ can enhance the standard model $B_{r}^{SM}(t\longrightarrow cWW)$ by several orders of magnitude for most of the parameter space. The peak of the branching ratio resonance emerges when the top-Higgs mass is between $2m_{W}$ and $m_{t}$. The branching ratio $ B_{r}(t\to c W W)$ can reach $ 10^{-3}$ in the narrow range.

hep-ph↗

arXiv2000

Production and decay of the neutral top-pion in high energy $e^{+}e^{-}$ colliders

We study the production and decay of the neutral top-pion $π_{t}^{0}$ predicted by topcolor-assisted technicolor(TC2) theory. Our results show that, except the dominant decay modes $b\bar{b}$, $\bar{t}c$ and $gg$, the $π_{t}^{0}$ can also decay into $γγ$ and $Z γ$ modes. It can be significantly produced at high energy $e^{+}e^{-}$ collider(LC) experiments via the processes $e^{+}e^{-}\to π_{t}^{0}γ$ and $e^{+}e^{-}\to Zπ_{t}^{0}$. We further calculate the production cross sections of the processes $e^{+}e^{-}\toγπ_{t}^{0}\toγ\bar{t}c$ and $e^{+}e^{-}\to Zπ_{t}^{0}\to Z\bar{t}c$. We find that the signatures of the neutral top-pion $π_{t}^{0}$ can be detected via these processes.

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arXiv2000

The bound on the mass of the new gauge boson $Z^{\prime}$ from the process $μ\longrightarrow 3e$

The new gauge boson $Z^{\prime}$ predicted by the strong top dynamical symmetry breaking models has significant contributions to the lepton flavor changing process $μ\longrightarrow 3e $. We consider the bound on the mass of the new gauge boson $Z^{\prime}$ from the experimental value of the branching ratio $Br(μ\longrightarrow 3e)$ in the framework of topcolor assisted technicolor models. We find that the precision experimental value of $Br(μ\longrightarrow 3e)$ gives a severe bound on the $Z^{\prime}$ mass $M_{Z^{\prime}}$. For $k_1 \leq 1$, $M_{Z^{\prime}}$ must be larger than 1.64 $TeV$.

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arXiv2000

Neutral top-pion and top-charm production in high energy $e^{+}e^{-}$ collisions

We calculate the contributions of the neutral top-pion, predicted by topcolor-assisted technicolor (TC2) theory, to top-charm production via the processes $γγ\longrightarrow\bar{t}c$ and $e^{+}e^{-}\longrightarrow γγ\longrightarrow \bar{t}c$ at the high energy linear $e^{+}e^{-}$ collider (LC) experiments. The cross section is of order $10^{-2}pb$ in most of the parameter space of TC2 theory, which may be detected at the LC experiments. So the process $e^{+}e^{-}\longrightarrow \bar{t}c$ can be used to detect the signature of TC2 theory.

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arXiv2000

Reexamination of the Constraint on Topcolor-Assisted Technicolor Models from R_b

Recent study on the charged top-pion correction to R_b shows that it is negative and large, so that the precision experimental value of R_b gives rise to a severe constraint on the topcolor-assisted technicolor models such that the top-pion mass should be of the order of 1 TeV. In this paper, we restudy this constraint by further taking account the extended technicolor gauge boson correction which is positive. With this positive contribution to R_b, the constraint on the topcolor-assisted technicolor models from R_b changes significantly. The top-pion mass is allowed to be in the region of a few hundred GeV depending on the models.

hep-ph↗

arXiv1996

Multiscale Technicolor and $b \to s γ$

Correction to the $b\rightarrow sγ$ branching ratio in the multiscale walking technicolor model (MWTCM) is examined. For the original MWTCM, the correction is too large to explain the recent CLEO data. We show that if topcolor is further introduced, the branching ratio in the topcolor assisted MWTCM can be in agreement with the CLEO data for a certain range of the parameters.

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arXiv1996

Study on the rare radiative decay $B_c \to D_s^*γ$ in the standard model and multiscale walking technicolor model

Applying the perturbative QCD ( PQCD ) method, we study the decay $B_c\rightarrow D_s^*γ$ in the standard model and multiscale walking technicolor model. In the SM, we find that the contribution of weak annihilation is more important than that of the electromagnetic penguin. The presence of Pseudo-Goldstone-Bosons in the MWTCM leads to a large enhancement in the rate of $B_c\rightarrow D_s^*γ$, but this model is in conflict with the branching ratio of $Z\rightarrow b\overline b$ ( $R_b$ ) and the CLEO data on the branching ratio BR ( $b\rightarrow sγ$ ). If topcolor is further introduced, the calculated results in the topcolor assisted MWTCM can be suppressed and be in agreement with the CLEO data for a certain range of the parameters.

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