The production of Bc and B＊ mesons at a Z-factory （an e＋e- collider operating at energies around the Z pole） is calculated up to the next-to-leading order （NLO） QCD accuracy. The results show that the dependence...The production of Bc and B＊ mesons at a Z-factory （an e＋e- collider operating at energies around the Z pole） is calculated up to the next-to-leading order （NLO） QCD accuracy. The results show that the dependence of the total cross sections on the renormalization scale/1 is suppressed by the corrections, and the NLO corrections enhance the total cross sections of B,. by 52% and of Bc＊ by 33% when the renormalization scale is taken at μ = 2mb. To observe the various behaviors of the production of the mesons Bc and Bc＊, such as the differential cross section vs. the out-going angle, the forward-backward asymmetry, and the distribution vs. the energy fraction z up to NLO QCD accuracy as well as the relevant K-factor （NLO to LO） for the production, are calculated, and it is pointed out that some of the observables obtained in the present work may be used as a specific precision test of the standard model.展开更多
In this paper, we investigate the decay of the Higgs boson to J/ψ（γ ） plus a photon based on NRQCD factorization. For the direct process, we calculate the decay width up to QCD NLO. We find that the decay width fo...In this paper, we investigate the decay of the Higgs boson to J/ψ（γ ） plus a photon based on NRQCD factorization. For the direct process, we calculate the decay width up to QCD NLO. We find that the decay width for process H → J/ψ（γ ） ＋γ direct production at the LO is significantly reduced by the NLO QCD corrections. For the indirect process, we calculate the H→γ＊γ, with virtual 7 substantially decaying to J/ψ（γ）, including all the SM Feynman diagrams. The decay width of indirect production is much larger than the direct decay width. Since it is very clean in experiment, the H →J/ψ（ γ） ＋γ decay could be observable at a 14 TeV LHC and it also offers a new way to probe the Yukawa coupling and New Physics at the LHC.展开更多
We perform the precision calculations for the e+e- → q-qˉ-(q-qˉ-= u-uˉ-, c-cˉ-, d-dˉ-, s-sˉ-) processes up to the QCD next-to-leading order(NLO) including full weak decays for the final T-odd mirror quarks in t...We perform the precision calculations for the e+e- → q-qˉ-(q-qˉ-= u-uˉ-, c-cˉ-, d-dˉ-, s-sˉ-) processes up to the QCD next-to-leading order(NLO) including full weak decays for the final T-odd mirror quarks in the littlest Higgs model with T-parity(LHT) at the Compact Linear Collider(CL√IC). We show the dependence of the leading order(LO) and NLO QCD corrected cross sections on the colliding energys, and provide the LO and QCD NLO kinematic distributions of final particles. The results show that the LO cross section can be enhanced by the NLO QCD correction and the√ K-factor increases obviously when the threshold of the on-shell q-qˉ--pair production approaches the colliding energys. The K-factor value varies in the range of 1.04 ～ 1.41 in our chosen parameter space. We find that a simple approximation of multiplying the LO kinematic distribution with the integrated K-factor is not appropriate for precision study of the e+e-→ q-qˉ-(q-qˉ-= u-uˉ-, c-cˉ-, d-dˉ-, s-sˉ-) processes, since the NLO QCD corrections are phase space dependent. It is necessary to calculate the differential cross sections including full NLO QCD corrections to get reliable results.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11275243,11275036,11447601,11535002,and 11675239)
文摘The production of Bc and B＊ mesons at a Z-factory （an e＋e- collider operating at energies around the Z pole） is calculated up to the next-to-leading order （NLO） QCD accuracy. The results show that the dependence of the total cross sections on the renormalization scale/1 is suppressed by the corrections, and the NLO corrections enhance the total cross sections of B,. by 52% and of Bc＊ by 33% when the renormalization scale is taken at μ = 2mb. To observe the various behaviors of the production of the mesons Bc and Bc＊, such as the differential cross section vs. the out-going angle, the forward-backward asymmetry, and the distribution vs. the energy fraction z up to NLO QCD accuracy as well as the relevant K-factor （NLO to LO） for the production, are calculated, and it is pointed out that some of the observables obtained in the present work may be used as a specific precision test of the standard model.
基金Supported by National Natural Science Foundation of China(11305001,11105083,11205003)
文摘In this paper, we investigate the decay of the Higgs boson to J/ψ（γ ） plus a photon based on NRQCD factorization. For the direct process, we calculate the decay width up to QCD NLO. We find that the decay width for process H → J/ψ（γ ） ＋γ direct production at the LO is significantly reduced by the NLO QCD corrections. For the indirect process, we calculate the H→γ＊γ, with virtual 7 substantially decaying to J/ψ（γ）, including all the SM Feynman diagrams. The decay width of indirect production is much larger than the direct decay width. Since it is very clean in experiment, the H →J/ψ（ γ） ＋γ decay could be observable at a 14 TeV LHC and it also offers a new way to probe the Yukawa coupling and New Physics at the LHC.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11275190,11375008,11375171the Fundamental Research Funds for the Central Universities under Grant No.WK2030040044
文摘We perform the precision calculations for the e+e- → q-qˉ-(q-qˉ-= u-uˉ-, c-cˉ-, d-dˉ-, s-sˉ-) processes up to the QCD next-to-leading order(NLO) including full weak decays for the final T-odd mirror quarks in the littlest Higgs model with T-parity(LHT) at the Compact Linear Collider(CL√IC). We show the dependence of the leading order(LO) and NLO QCD corrected cross sections on the colliding energys, and provide the LO and QCD NLO kinematic distributions of final particles. The results show that the LO cross section can be enhanced by the NLO QCD correction and the√ K-factor increases obviously when the threshold of the on-shell q-qˉ--pair production approaches the colliding energys. The K-factor value varies in the range of 1.04 ～ 1.41 in our chosen parameter space. We find that a simple approximation of multiplying the LO kinematic distribution with the integrated K-factor is not appropriate for precision study of the e+e-→ q-qˉ-(q-qˉ-= u-uˉ-, c-cˉ-, d-dˉ-, s-sˉ-) processes, since the NLO QCD corrections are phase space dependent. It is necessary to calculate the differential cross sections including full NLO QCD corrections to get reliable results.
