arXiv subjects

Zhang Ren-You

Publications and source records attributed to Zhang Ren-You.

At least 73 records · Page 4Linked to original sources

arXiv2010

Seesaw Type I and III at the LHeC

We study the potential of testing the seesaw type I and III models at the LHeC, an e-p collision mode at the CERN collider. The e-p collision mode provides an excellent place to study lepton number violating process e^- p \to N j + X \to l^+ W^- j + X with W^- into hadron jets. Here N is a heavy Majorana neutrino and j is a hard hadron jet. With the electron energy E_e = 140 GeV and proton energy E_p = 7 TeV, we find that the cross section for the heavy neutrino N production can be as large as a few fb for the mass scale as high as 1 TeV, higher than what can be achieved by the p-p collision mode of LHC with the same related heavy neutrino couplings.

hep-ph↗

arXiv2010

Next-to-leading order QCD predictions for the hadronic $WH$+jet production

We calculate the next-to-leading order(NLO) QCD corrections to the $WH^0$ production in association with a jet at hadron colliders. We study the impacts of the complete NLO QCD radiative corrections to the integrated cross sections, the scale dependence of the cross sections, and the differential cross sections ($\frac{d σ}{d\cosθ}$, $\frac{d σ}{dp_T}$) of the final $W$-, Higgs-boson and jet. We find that the corrections significantly modify the physical observables, and reduce the scale uncertainty of the LO cross section. Our results show that by applying the inclusive scheme with $p_{T,j}^{cut}=20 GeV$ and taking $m_H=120 GeV$, $μ=μ_0\equiv\frac{1}{2}(m_W+m_H)$, the K-factor is 1.15 for the process $p\bar p \to W^{\pm}H^0j+X$ at the Tevatron, while the K-factors for the processes $pp \to W^-H^0j+X$ and $pp \to W^+H^0j+X$ at the LHC are 1.12 and 1.08 respectively. We conclude that to understand the hadronic associated $WH^0$ production, it is necessary to study the NLO QCD corrections to $WH^0j$ production process which is part of the inclusive $WH^0$ production.

hep-ph↗

arXiv2010

Full electroweak one-loop corrections to $W^+ W^-Z^0$ production at the ILC

The precise investigation of the $W^+ W^-Z^0$ production at the $e^+e^-$ International Linear Collider(ILC) is of crucial importance in probing the couplings between massive vector gauge bosons and discovering the signature of new physics beyond the standard model(SM). We study the full one-loop EW effects on the observables, such as, the total cross section, the differential cross section of the invariant mass of $W$-pair, the distribution of the angle between $W$-pair, the production angle distributions of $W$- and $Z^0$-boson, the distributions of the transverse momenta of final $W$- and $Z^0$-boson, and the forward-backward charge asymmetry of $W^-$-boson. Our numerical results show that the EW relative correction to the total cross sections($δ_{ew}$) varies from -18.9% to -5.7% when $m_H=120 GeV$ and $\sqrt{s}$ goes up from $300 GeV$ to $1 TeV$.

hep-ph↗

arXiv2009

One-loop QCD and electroweak corrections to $t\bar{t}Z^0$ production at an $e^+e^-$ linear collider

We study the impact of the full ${\cal O}(α_{s})$ QCD and ${\cal O}(α_{ew})$ electroweak (EW) radiative corrections to the $e^+e^- \to t \bar t Z^0$ process in the standard model (SM), and investigate the dependence of the lowest-order(LO), one-loop QCD and EW corrected cross sections on colliding energy $\sqrt{s}$. The LO, QCD and EW corrected spectrums of the invariant mass of $t\bar t$-pair and the distributions of the transverse momenta of final top-quark and $Z^0$-boson are presented. The numerical results show that the one-loop QCD correction enhances the LO cross section, but the EW one-loop correction generally suppresses the LO cross section with our chosen parameters. In the case of $m_H=120 GeV$, the QCD relative corrections can reach 43.16% when $\sqrt{s} = 500 GeV$, while the EW relative corrections have the values of -9.24%, -4.36% and -5.81%, when $\sqrt{s} = 500 GeV$, $800 GeV$, 1.2 TeV$, respectively.

hep-ph↗

arXiv2009

QCD corrections to associated production of $t\bar tγ$ at hadron colliders

We report on the next-to-leading order(NLO) QCD computation of top-quark pair production in association with a photon at the Fermilab Tevatron RUN II and CERN Large Hadron Collider(LHC). We describe the impact of the complete NLO QCD radiative corrections to this process, and provide the predictions of the leading order(LO) and NLO integrated cross sections, distributions of the transverse momenta of top-quark and photon for the LHC and Tevatron, and the LO and NLO forward-backward top-quark charge asymmetries for the Tevatron. We investigate the dependence of the LO and NLO cross sections on the renormalization/factorization scale, and find the scale dependence of the LO cross section is obviously improved by the NLO QCD corrections. The K-factor of the NLO QCD correction is $0.977(1.524)$ for the Tevatron(LHC).

hep-ph↗

arXiv2009

QCD corrections to associated Higgs boson production with a W boson pair at the LHC

The Higgs boson production in association with a pair of W-bosons at the Large Hadron Collider(LHC) can be used to probe the coupling between Higgs boson and vector gauge bosons and discover the signature of new physics. We describe the impact of the complete QCD NLO radiative corrections and the gluon-gluon fusion subprocesss to the cross section of this process at the LHC, and investigate the dependence of the leading order(LO) and the QCD corrected cross sections on the fctorization/renormalization energy scale and Higgs boson mass. We present the LO and QCD corrected distributions of the invariant mass of W-boson pair and the transverse momenta of final W and Higgs boson. We find that the QCD NLO corrections and the contribution from gluon-gluon fusion subprocess significantly modify the LO distributions, and the scale dependence of the QCD corrected cross section is badly underestimated by the LO results. Our numerical results show that the K-factor of the QCD correction varies from 1.48 to 1.64 when $m_H$ goes up from $100 GeV$ to $160 GeV$. We find also the QCD correction from \gghww subprocess at the LHC is significant, and should be considered in precise experiment.

hep-ph↗

arXiv2008

SUSY QCD impact on top-pair production associated with a $Z^0$-boson at a photon-photon collider

The top-pair production in association with a $Z^0$-boson at a photon-photon collider is an important process in probing the coupling between top-quarks and vector boson and discovering the signature of possible new physics. We describe the impact of the complete supersymmetric QCD(SQCD) next-to-leading order(NLO) radiative corrections on this process at a polarized or unpolarized photon collider, and make a comparison between the effects of the SQCD and the standard model(SM) QCD. We investigate the dependence of the lowest-order(LO) and QCD NLO corrected cross sections in both the SM and minimal supersymmetric standard model(MSSM) on colliding energy $\sqrt{s}$ in different polarized photon collision modes. The LO, SM NLO and SQCD NLO corrected distributions of the invariant mass of $t\bar t$-pair and the transverse momenta of final $Z^0$-boson are presented. Our numerical results show that the pure SQCD effects in \ggttz process can be more significant in the $+ +$ polarized photon collision mode than in other collision modes, and the relative SQCD radiative correction in unpolarized photon collision mode varies from 32.09% to $-1.89 %$ when $\sqrt{s}$ goes up from $500 GeV$ to $1.5 TeV$.

hep-ph↗

arXiv2008

Precise predictions for the Higgs production in association with a W-boson pair at ILC

The Higgs-boson production in association with a W-boson pair at $e^+e^-$ linear colliders is one of the important processes in probing the coupling between Higgs-boson and vector gauge bosons and discovering the signature of new physics. We describe the impact of the complete electroweak(EW) radiative corrections of ${\cal O}(α_{ew})$ to this process in the standard model(SM) at the International Linear Collider(ILC), and investigate the dependence of the lowest-order(LO) and EW next-to-leading order(NLO) corrected cross sections on colliding energy $\sqrt{s}$ and Higg-boson mass. The LO and NLO EW corrected distributions of the invariant mass of W-boson pair and the transverse momenta of final $W$- and Higgs-boson are presented. Our numerical results show that the relative EW radiative correction($δ_{ew}$) varies from -19.4% to 0.2% when $m_H=120 GeV$ and $\sqrt{s}$ goes up from $300 GeV$ to $1.2 TeV$.

hep-ph↗

arXiv2008

Complete one-loop electroweak corrections to $ZZZ$ production at the ILC

We study the complete ${\cal O}(α_{ew})$ electroweak (EW) corrections to the production of three $Z^0$-bosons in the the framework of the standard model(SM) at the ILC. The leading order and the EW next-to-leading order corrected cross sections are presented, and their dependence on the colliding energy $\sqrt{s}$ and Higgs-boson mass $m_{H}$ is analyzed. We investigate also the LO and one-loop EW corrected distributions of the transverse momentum of final $Z^0$ boson, and the invariant mass of $Z^0Z^0$-pair. Our numerical results show that the EW one-loop correction generally suppresses the tree-level cross section, and the relative correction with $m_{H}=120 GeV(150 GeV)$ varies between $-15.8%(-13.9%)$ and $-7.5%(-6.2%)$ when $\sqrt{s}$ goes up from $350 GeV$ to $1 TeV$.

hep-ph↗

arXiv2008

One-loop QCD corrections to the $e^+e^- \to W^+ W^- b\bar b$ process at the ILC

We study the full contributions at the leading order(LO) and QCD next-to-leading order(NLO) to the cross section of the \eewwbb process in the standard model(SM) at the ILC. In dealing the resonance problem we adopted the complex mass scheme in both tree-level and one-loop level perturbative calculations. Our numerical results show that the K-factor varies from 1.501 to 0.847 when $\sqrt{s}$ goes up from $360 GeV$ to $1.5 TeV$. We investigate the dependence of the LO and QCD NLO corrected cross sections of process \eewwbb on colliding energy $\sqrt{s}$ and Higgs-boson mass. We also present the results of the LO and QCD NLO corrected distributions of the transverse momenta of final particles, and the invariant masses of $Wb$-, $b\bar b$- and $WW$-pair.

hep-ph↗

arXiv2007

Revisiting the QCD corrections to the R-parity violating processes $p\bar{p}/pp \to eμ+X$

We present the theoretical predictions up to QCD NLO for the cross section of high-mass electron-muon pair production at the Tevatron and the LHC, considering only the dominant contributions from the third-generation sneutrino. The dependence of the renormalization and factorization scales on the total cross section, and the effects on the K-factor due to the uncertainty of parton distribution function(PDF) have been carefully investigated. By considering soft-gluon resummation effects to all order in $α_s$ of leading logarithm, we present the transverse momentum distributions of the final $eμ$ pair.

hep-ph↗

arXiv2007

QCD corrections to t\bar t b \bar b productions via photon-photon collisions at linear colliders

We calculated the complete next-to-leading order(NLO) QCD corrections to the $t\bar t b \bar b$ production process at a $γγ$ collider in the standard model(SM). The calculation of the one-loop QCD correction includes the evaluations of the hexagon and pentagon amplitudes. We studied the NLO QCD corrected total cross section, the distributions of transverse momenta of final top- and bottom-quark states, and the dependence of the cross section on renormalization scale $μ$. It shows that NLO QCD correction generally increases the LO cross section in our chosen parameter space, and the K-factor varies from 1.70 to 1.14 when colliding energy goes up from $400 GeV$ to $2 TeV$. We find that the correction distinctly changes the distributions of transverse momenta of the final top- and bottom-quark states, and the NLO QCD correction obviously improves the independence of the cross section for process $γγ\to t\bar t b\bar b$ on the renormalization scale.

hep-ph↗

arXiv2007

Associated production of graviton with $e^+e^-$ pair via photon-photon collisions at a linear collider

We investigate the process \rreeG at the future International Linear Collider(ILC), where G_n is the Kaluza-Klein graviton in the Large Extra Dimension Model. When the fundamental energy scale is of a few ${\rm TeV}$, the cross section of this process can reach several hundred fb at a photon-photon collider with $\sqrt{s}=500 \sim 1000 GeV$, and the cross section in J=2 polarized photon collision mode is much larger than that in J=0 polarized photon collision mode. We present strategies to distinguish the graviton signal from numerous SM backgrounds, and find that the graviton signal with extra dimensions $δ=3$ can be detected when ${\rm M_S} \le 2.67(1.40) {\rm TeV}$ and $γγ$ c.m.s. energy $\sqrt{s}=1000(500) {\rm GeV}$ in unpolarized photon collision mode, while the detecting upper limit can be increased to 2.79(1.44) ${\rm TeV}$ in $+ -$ ($λ_1=1$, $λ_2=-1$) polarized photon collision mode(with photon polarization efficiency $P_γ=0.9$).

hep-ph↗

arXiv2007

The effects of the little Higgs models on $t\bar{t} h^0$ production via $γγ$ collision at linear colliders

In the frameworks of the littlest Higgs($LH$) model and its extension with T-parity($LHT$), we studied the associated $t\bar th^0$ production process $e^+ e^- \to γγ\to t \bar t h^0$ at the future $e^+e^-$ linear colliders up to QCD next-to-leading order. We present the regions of $\sqrt{s}-f$ parameter space in which the $LH$ and $LHT$ effects can and cannot be discovered with the criteria assumed in this paper. The production rates of process $γγ\to t \bar t h^0$ in different photon polarization collision modes are also discussed. We conclude that one could observe the effects contributed by the $LH$ or $LHT$ model on the cross section for the process $e^+ e^- \to γγ\to t \bar t h^0$ in a reasonable parameter space, or might put more stringent constraints on the $LH$/$LHT$ parameters in the future experiments at linear colliders.

hep-ph↗

arXiv2007

Flavor changing effects on single charged Higgs boson production associated with a bottom-charm pair at CERN Large Hadron Collider

We study flavor changing effects on the \ppbchT process at the Large Hadron Collider(LHC), which are inspired by the left-handed up-type squark mixings in the Minimal Supersymmetric Standard Model(MSSM). We find that the SUSY QCD radiative corrections to $bcH^\pm$ coupling can significantly enhance the cross sections at the tree-level by a factor about $1.5 \sim 5$ with our choice of parameters. We conclude that the squark mixing mechanism in the MSSM makes the \ppbchT process a new channel for discovering a charged Higgs boson and investigating flavor changing effects.

hep-ph↗

arXiv2007

Full one-loop electroweak corrections to $h^0(H^0,A^0) H^\pm W^\mp$ associated productions at $e^+e^-$ linear colliders

We study the complete one-loop electroweak(EW) corrections to the processes of single charged Higgs boson production associated with a neutral Higgs boson$(h^0,H^0,A^0)$ and a gauge boson $W^\pm$ in the framework of the minimal supersymmetric standard model(MSSM). Numerical results at the ${\rm SPS1a'}$ benchmark point as proposed in the SPA project, are presented for demonstration. We find that for the process $e^+e^-\to h^0H^\pm W^\mp$ the EW relative correction can be either positive or negative and in the range of $-15%\sim 20%$ in our chosen parameter space. While for the processes $e^+e^-\to H^0(A^0)H^\pm W^\mp$ the corrections generally reduce the Born cross sections and the EW relative corrections are typically of order $-10%\sim -20%$.

hep-ph↗

arXiv2006

QCD corrections to the R-parity violating processes $p\bar{p}/pp \to eμ+X$ at hadron colliders

We present the QCD corrections to the processes $p\bar{p}/pp \to eμ+X$ at the Tevatron and the CERN large hadron collider(LHC). The numerical results show that variation of K factor is in the range between $1.28(1.32)$ and $1.79(1.58)$ at the Tevatron(LHC). We find that the QCD correction part from the one-loop gluon-gluon fusion subprocess is remarkable at the LHC and should be taken into account.

hep-ph↗

arXiv2006

The annihilation decays $B^-_c \to η^{'}(η,π^0) l^- \barν$

We investigate the simileptonic OZI-forbidden annihilation decays $B^-_c \to η^{'}(η,π^0) l^- \barν$ for $l=μ,e$ in the perturbative QCD, and carry out a precise calculation without any approximation for the one-loop contributions, which involves integrals of 4- and 5-point loop functions. Our results show that the branching ratios of decays $B^-_c \to η^{'} l^- \barν$, $B^-_c \to ηl^- \barν$ and $B^-_c \to π^0 l^- \barν$, turn out to be of orders $10^{-4}$, $10^{-5}$ and $10^{-6}$, respectively, which could be observable in the future experiments at the LHC.

hep-ph↗