arXiv subjects

Ma Wen-Gan

Publications and source records attributed to Ma Wen-Gan.

At least 91 records · Page 5Linked to original sources

arXiv2006

Full one-loop electroweak and NLO QCD corrections to the associated production of chargino and neutralino at hadron colliders

We study the process of the association production of chargino and neutralino including the NLO QCD and the complete one-loop electroweak corrections in the framework of the minimal supersymmetric standard model(MSSM) at the Fermilab Tevatron and the CERN Large Hadron Collider (LHC). In both the NLO QCD and one-loop electroweak calculations we apply the algorithm of the phase-space slicing(PSS) method. We find that the NLO QCD corrections generally increase the Born cross sections, while the electroweak relative corrections decrease the Born cross section in most of the chosen parameter space. The NLO QCD and electroweak relative corrections typically have the values of about 32% and -8% at the Tevatron, and about 42% and -6% at the LHC respectively. The results show that both the NLO QCD and the complete one-loop electroweak corrections to the processes $p \bar p/pp \to \widetildeχ_1^{\pm} \widetildeχ_2^0+X$ are generally significant and should be taken into consideration in precision experimental analysis.

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arXiv2006

NLO supersymmetric QCD corrections to the $t \bar b H^-$ associated production at hadron colliders

We present the next-to-leading order QCD corrected total cross sections and the distributions of the transverse momenta of the final anti-bottom-quark, top-quark and charged Higgs-boson for the processes of $p\bar p/pp \to t\bar b H^-+X$ in the minimal supersymmetric standard model(MSSM) at the Tevatron and the LHC. We find that the NLO QCD corrections significantly modify the leading-order distributions of the transverse momenta of final particles($p_T^b$, $p_T^t$ and $p_T^{H^-}$), and the total NLO QCD corrections reduce the dependence of the cross section on the renormalization and factorization scales, especially the NLO QCD corrected cross sections at the LHC are nearly independent of these scales. Our results show that the relative correction is obviously related to $m_{H^-}$ and $\tanβ$, and the total NLO QCD relative corrections can be beyond -50% at the Tevatron and approach -40% at the LHC in our chosen parameter space.

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arXiv2005

Full one-loop supersymmetric corrections to charged Higgs boson pair production in $γγ$ collisions

The complete one-loop electroweak corrections to charged Higgs boson pair production in $γγ$ collision mode at linear colliders in the minimal supersymmetric standard model (MSSM), are calculated in this paper. We discuss the dependence of the corrections to the subprocess $γγ\to H^{+}H^{-}$ on the related parameters, such as the colliding energy, charged Higgs boson mass $M_{H^{\pm}}$ and some supersymmetric parameters $\tan β$, $M_{SUSY}$ and gaugino mass parameter $M_2$. We find that the corrections generally reduce the Born cross sections and the relative one-loop corrections to both the subprocess typically in the range of -10% to -30%. We also present the numerical results at the SPS1a' point from the SPA project. We conclude that the full one-loop electroweak corrections to subprocess $γγ\to H^{+}H^{-}$ and the parent process $e^+e^- \to γγ\to H^{+}H^{-}$ are significant and therefore should be considered in precise analysis of charged Higgs boson pair productions via $γγ$ collision at future linear colliders.

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arXiv2005

Full one-loop supersymmetric electroweak corrections to $t\bar{t}h^{0}$ associated production in $e^+e^-$ annihilation

We present a precise calculation of the lightest neutral Higgs boson production associated with top quark pair at a linear collider. The full one-loop electroweak ${\cal O}(α_{ew})$ contributions to the process $e^+e^- \to t\bar t h^0$ within the minimal supersymmetric standard model (MSSM) are included. We analyze the dependence of the electroweak corrections on the MSSM parameters such as $M_{A^0}$, $\tanβ$, $M_2$, $A_{f}$, $M_{SUSY}$ and $μ$. The results show that the full one-loop electroweak radiative corrections turn out to be about -20% quantitatively and thus are important for future $e^+e^-$ linear colliders.

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arXiv2005

NLO Supersymmetric QCD Corrections to $t \bar t h^0$ Associated Production at Hadron Colliders

We calculate NLO QCD corrections to the lightest neutral Higgs boson production associated with top quark pair at hadron colliders in the minimal supersymmetric standard model(MSSM). Our calculation shows that the total QCD correction significantly reduces its dependence on the renormalization/factorization scale. The relative correction from the SUSY QCD part approaches to be a constant, if either $M_S$ or $m_{\tilde{g}}$ is heavy enough. The corrections are generally moderate(in the range of few percent to 20%) and under control in most of the SUSY parameter space. The relative correction is obviously related to $m_{\tilde{g}}$, $A_t$ and $μ$, but not very sensitive to $\tanβ$, $M_S$ at both the Tevatron and the LHC with our specified parameters.

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arXiv2005

Pair Production of Charged Higgs Bosons from Bottom-Quark Fusion

For very large values of $\tanβ$, charged Higgs boson pair production at the Large Hadron Collider (LHC) from the scattering of two bottom quarks can proceed dominantly. We investigated the cross sections of charged Higgs boson pair production via the subprocess $b\bar{b} \to H^+H^-$ at the LHC including the next-to-leading order (NLO) QCD corrections in the minimal supersymmetric standard model (MSSM). We find that the NLO QCD corrections can significantly reduce the dependence of the cross sections on the renormalization and factorization scales.

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arXiv2005

The effects of large extra dimensions on associated $t\bar{t} h^0$ production at linear colliders

In the framework of the large extra dimensions (LED) model, the effects of LED on the processes \rrtth and \eetth at future linear colliders are investigated in both polarized and unpolarized collision modes. The results show that the virtual Kaluza-Klein (KK) graviton exchange can significantly modify the standard model expectations for these processes with certain polarizations of initial states. The process \rrtth with $\sqrt{s}=3.5 TeV$ allows the effective scale $Λ_T$ to be probed up to 7.8 and 8.6 TeV in the unpolarized and $P_γ = 0.9$, J=2 polarized $γγ$ collision modes, respectively. For the \eetth process with $\sqrt{s}=3.5 TeV$, the upper limits of $Λ_T$ to be observed can be 6.7 and 7.0 TeV in the unpolarized and $P_{e^+} = 0.6$, $P_{e^-} = 0.8$, $-+$ polarized $e^+e^-$ collision modes, respectively. We find the \rrtth channel in J=2 polarized photon collision mode provides a possibility to improve the sensitivity to the graviton tower exchange.

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arXiv2005

Full one-loop QCD and electroweak corrections to sfermion pair production in $γγ$ collisions

We have calculated the full one-loop electroweak (EW) and QCD corrections to the third generation scalar-fermion pair production processes $e^+e^- \to γγ\to \tilde{f_i}\bar{\tilde{f_i}} (f=t,b,τ)$ at an electron-positron linear collider(LC) in the minimal supersymmetric standard model (MSSM). We analyze the dependence of the radiative corrections on the parameters such as the colliding energy $\sqrt{\hat s}$ and the SUSY fundamental parameters $A_f$, $\tan β$, $μ$, $M_{SUSY}$ and so forth. The numerical results show that the EW corrections to the squark-, stau-pair production processes and QCD corrections to the squark-pair production processes give substantial contributions in some parameter space. The EW relative corrections to squark-pair production processes can be comparable with QCD corrections at high energies. Therefore, these EW and QCD corrections cannot be neglected in precise measurement of sfermion pair productions via $γγ$ collision at future linear colliders.

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arXiv2004

Probing R-parity violating interactions via $p\bar{p} \to eμ+X$ channel on Tevatron

We investigated the lepton flavor violation processes $p\bar{p} \to eμ+X$ induced by R-parity violating interactions at the Tevatron hadron collider. The theoretical calculation and Monte Carlo simulation demonstrate that with a set of suitable cuts on experimental observables, one might be capable to reduce the standard model physical background to a controllable level so that the signals of R-parity violating interactions could be detected distinctively. Furthermore, clear sneutrino information could be abstracted from the purified event sample where other SUSY scalar quark 'pollution' is heavy suppressed. We conclude that with a reasonable assumption of $10fb^{-1}$ integrated luminosity, the Experiments at the Tevatron machine would have potential to discover sneutrino in the region of $m_{\tildeν}\le400GeV$ via lepton flavor violation $eμ$ production channels, or extend the mass scale constraint up to $m_{\tildeν}\ge 550 GeV$ at 95% CL.

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arXiv2004

Probing Lepton Flavor Violation Signal Induced by R-violating Minimal Supersymmetric Standard Model at a Linear Collider

The lepton-flavor violation (LFV) effect at an $e^+e^-$ linear collider (LC), in the frame of R-parity violating minimal supersymmetric standard model is studied. We take the R-parity violating processes $e^+e^-\to e^{\mp}μ^{\pm}$ as signal, and define the summation of the two processes as ``experiment'' observable. We find that the cross-section summation can reach $\cal{O}$$(10^1)fb$ in the parameter space without sneutrino resonance effect($\sqrt{s} \sim m_{\tildeν}$). The summation treatment manifests uniform differential distribution on $\cosθ$, where $θ$ denotes the polar angles of both outgoing $e^+/e^-$ respectively to incoming electron beam in two signal processes. The uniform feature together with $eμ$ collinearity would help to reduce the SM background dramatically. Consequently we conclude that at a $500 GeV$ LC with $480 fb^{-1}$ annual luminosity, it's either possible to detect the distinctive R-violating LFV $eμ$ signal, or exclude sneutrino to $m_{\tildeν}>1.1 TeV$ at 95% CL in the machine's biennial runtime interval.

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arXiv2004

${\cal O}(α_{s})$ QCD and ${\cal O}(α_{ew})$ electroweak corrections to $t\bar{t}h^0$ production in $γγ$ collision

We calculate the ${\cal O}(α_{s})$ QCD and ${\cal O}(α_{\rm ew})$ electroweak one-loop corrections in the Standard Model framework, to the production of an intermediate Higgs boson associated with $t\bar{t}$ pair via $γγ$ fusion at an electron-positron linear collider (LC). We find the ${\cal O}(α_{s})$ QCD corrections can be larger than the ${\cal O}(α_{\rm ew})$ electroweak ones, with the variations of the Higgs boson mass $m_{h}$ and $e^+e^-$ colliding energy $\sqrt{s}$. Both corrections may significantly decrease or increase the Born cross section. The numerical results show that the relative corrections from QCD to the process \eep may reach 34.8%, when $\sqrt{s}=800$ GeV and $m_h=200$ GeV, while those from electroweak can be -13.1%, -15.8% and -12.0%, at $\sqrt{s} = 800$ GeV, 1 TeV and 2 TeV respectively.

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arXiv2003

Pseudoscalar Higgs boson production associated with a single bottom quark at hadron colliders

We compute the complete next-to-leading order (NLO) SUSY-QCD corrections for the associated production of a pseudoscalar Higgs boson with a bottom quark via bottom-gluon fusion at the CERN Large Hadron Collider (LHC) and the Fermilab Tevatron. We find that the NLO QCD correction in the MSSM reaches $40%\sim50%$ at the LHC and $45%\sim80%$ at the Tevatron in our chosen parameter space.

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arXiv2003

Full ${\cal O}(α_{ew})$ electroweak corrections to $e^+e^- \to H H Z$

We calculate the full ${\cal O}(α_{ew})$ electroweak corrections to the Higgs pair production process $e^+ e^- \to H H Z$ at an electron-positron linear collider in the standard model, and analyze the dependence of the Born cross section and the corrected cross section on the Higgs boson mass $m_H$ and the c.m. energy $\sqrt{s}$. To see the origin of some of the large corrections clearly, we calculate the QED and genuine weak corrections separately. The numerical results show that the corrections significantly suppress or enhance the Born cross section, depending on the values of $m_H$ and $\sqrt{s}$. For the c.m. energy $\sqrt{s} = 500 GeV$, which is the most favorable colliding energy for $H H Z$ production with intermediate Higgs boson mass, the relative correction decreases from -5.3% to -11.5% as $m_H$ increases from 100 to 150 GeV. For the range of the c.m. energy where the cross section is relatively large, the genuine weak relative correction is small, less than 5%.

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arXiv2003

R-parity violation effect on the top-quark pair production at linear colliders

We investigate in detail the effects of the R-parity lepton number violation in the minimal supersymmetric standard model (MSSM) on the top-quark pair production via both $e^--e^+$ and $γ-γ$ collision modes at the linear colliders. We find that with the present experimental constrained $\rlap/{R}$ parameters, the effect from $\rlap/{R}$ interactions on the processes $e^+e^-\to t\bar{t}$ and $e^+e^- \to γγ\to t\bar{t}$ could be significant and may reach -30% and several percent, respectively. Our results show that the $\rlap/{R}$ effects are sensitive to the c.m.s. energy and the relevant $\rlap/{R}$ parameters. However, they are not sensitive to squark and slepton masses when $m_{\tilde{q}} \geq 400 GeV$ (or $m_{\tilde{l}} \geq 300 GeV$) and are almost independent on the $\tanβ$

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arXiv2003

Neutral Higgs boson pair production via $γγ$ collision in the minimal supersymmetric standard model at linear colliders

We investigate in detail the $γγ$ fusion production mechanisms of two neutral Higgs bosons ($h^0A^0$, $ H^0A^0$, $h^0H^0$ and $H^0H^0$) within the framework of the mSUGRA-inspired minimal supersymmetric standard model(MSSM) at an $e^+e^-$ linear colliders, which provide a probe of the trilinear Higgs self-couplings. We calculate the dependence of the production rates on Higgs boson masses, the ratio of the vacuum expectation values $\tan β$ and the CMS energy $\sqrt{s}$. We find that the cross section for the $H^0H^0$ production at LC can reach $0.2 fb$, while the cross section of $A^0H^0$ production is only $10^{-4}\sim 10^{-3} fb$ under our parameters.

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arXiv2003

Electroweak radiative corrections to $e^+e^- \to t \bar{t} h$ at linear colliders

We calculate the ${\cal O}(α_{\rm ew})$ electroweak radiative corrections to $e^+ e^- \to t \bar{t} h$ at a electron-positron linear collider (LC) in the standard model. We analyze the dependence of the ${\cal O}(α_{\rm ew})$ corrections on the Higgs boson mass $m_{h}$ and colliding energy $\sqrt{s}$, and find that the corrections significantly decrease or increase the Born cross section depending on the colliding energy. The numerical results show that the ${\cal O}(α_{\rm ew})$ relative correction is strongly related to the Higgs boson mass when $\sqrt{s}=500 GeV$, and for $m_h = 150 GeV$ the relative correction ranges from -31.3% to 2.3% as the increment of the colliding energy from 500 GeV to 2 TeV.

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arXiv2003

Higgs-Boson Production Associated with a Single Bottom Quark in Supersymmetric QCD

Due to the enhancement of the couplings between Higgs boson and bottom quarks in the minimal sypersymmetric standard model (MSSM), the cross section of the process pp(p\bar{p}) \to h^0b(h^0\bar{b})+X at hadron colliders can be considerably enhanced. We investigated the production of Higgs boson associated with a single high-p_T bottom quark via subprocess bg(\bar{b}g) \to h^0b(h^0\bar{b}) at hadron colliders including the next-to-leading order (NLO) QCD corrections in MSSM. We find that the NLO QCD correction in the MSSM reaches 50%-70% at the LHC and 60%-85% at the Fermilab Tevatron in our chosen parameter space.

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arXiv2002

$A^{0}Z^{0}$ associated production at the Large Hadron Collider in the minimal supersymmetric standard model

We investigate in detail the $A^{0}Z^{0}$ associated production process $pp \to A^0Z^0+X$ within the framework of the minimal supersymmetric standard model (MSSM) at the CERN Large Hadron Collider (LHC), considering both contributions from the Drell-Yan and gluon fusion subprocesses. We focus on the deviations from the general two-Higgs-doublet model (2HDM) arising in the MSSM. We also discuss the contributions of the two $A^{0}Z^{0}$ associated production subprocesses in the MSSM at the LHC, and analyse the dependences of the total cross section on neutral CP-odd Higgs boson mass $m_A$ and $\tanβ$ in the mSUGRA scenario. We find that the contribution from loop mediated gluon fusion subprocess can be competitive with that from the Drell-Yan subprocess in some parameter space.

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