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[en] Highlights: • Propose a new efficient and more precise three-step complex network reliability approximation approach. • Propose a most reliable k disjoint paths identification algorithm that can in general identify more edge-disjoint minimal path sets than the greedy algorithm. • Propose a new algorithm to identify a set of edge-disjoint minimal cut sets. • Describe a multi-objective approach for expanding a complex networked system to enhance its reliability. -- Abstract: The economic development and social well-being of a society are highly dependent on many complex networked systems, such as power transmission and distribution, telecommunications, transportation and so forth, which calls for the enhancement of their reliable functioning. To fulfil this purpose, the first essential step is to effectively evaluate their reliability, which is intractable since they usually contain a large amount of components organized via complex structures. To deal with this computational complexity, this research proposes a new network reliability evaluation approach by identifying minimal path sets that may have edges in common, but consist of only parallel and series structures when considered together. Our proposed approach can efficiently approximate network reliability more precisely than the existing edge-packing methods. We then propose a multi-objective optimization approach to solve the problem of expanding a complex networked system to enhance its reliability. The solutions obtained by our proposed approach can help in well understanding the trade-off between the reliability and cost of network expansion solutions. Finally, an application of the proposed method to the high-speed railway network of China is implemented.

[en] We present the calculations of the complete next-to-leading order (NLO) QCD effects on the single top productions induced by model-independent tqg flavor-changing neutral-current couplings at hadron colliders. Our results show that, for the tcg coupling, the NLO QCD corrections can enhance the total cross sections by about 60% and 30%, and for the tug coupling by about 50% and 20% at the Tevatron and LHC, respectively, which means that the NLO corrections can increase the experimental sensitivity to the flavor-changing neutral-current couplings by about 10%-30%. Moreover, the NLO corrections reduce the dependence of the total cross sections on the renormalization or factorization scale significantly, which lead to increased confidence on the theoretical predictions. Besides, we also evaluate the NLO corrections to several important kinematic distributions, and find that for most of them the NLO corrections are almost the same and do not change the shape of the distributions.

[en] We present the complete next-to-leading order (NLO) QCD predictions for the tγ associated production induced by model-independent tqγ and tqg flavor-changing neutral-current (FCNC) couplings at hadron colliders, respectively. We also consider the mixing effects between the tqγ and tqg FCNC couplings for this process. Our results show that, for the tqγ couplings, the NLO QCD corrections can enhance the total cross sections by about 50% and 40% at the Tevatron and LHC, respectively. Including the contributions from the tqγ, tqg FCNC couplings and their mixing effects, the NLO QCD corrections can enhance the total cross sections by about 50% for the tuγ and tug FCNC couplings, and by about 80% for the tcγ and tcg FCNC couplings at the LHC, respectively. Moreover, the NLO corrections reduce the dependence of the total cross section on the renormalization and factorization scale significantly. We also evaluate the NLO corrections for several important kinematic distributions.

[en] We investigate the QCD effects in the production of neutral Higgs bosons via bottom quark fusion in both the standard model and the minimal supersymmetric standard model at the CERN Large Hadron Collider. We include the next-to-leading order (NLO) QCD corrections (including supersymmetric QCD) and the threshold resummation effects. We use the soft-collinear effective theory to resum the large logarithms near threshold from soft gluon emission. Our results show that the resummation effects can enhance the total cross sections by about 5% compared with the NLO results.

[en] We present the exact next-to-leading order (NLO) QCD corrections to the dijet production induced by the quark contact interactions at the CERN Large Hadron Collider. We show that, as compared to the exact calculation, the scaled NLO QCD prediction adopted by the ATLAS Collaboration has overestimated the new physics effect on some direct observables by more than 30% and renders a higher limit on the quark compositeness scale. The destructive contribution from the exact NLO correction will also lower the compositeness scale limit set by the CMS Collaboration.

[en] We present a complete next-to-leading order (NLO) QCD calculation to a heavy resonance production and decay into a top quark pair at the LHC, where the resonance could be either a Randall-Sundrum Kaluza-Klein graviton G or an extra gauge boson Z^'. The complete NLO QCD corrections can enhance the total cross sections by about 80%-100% and 20%-40% for the G and the Z^', respectively, depending on the resonance mass. We also explore in detail the NLO corrections to the polar angle distributions of the top quark, and our results show that the shapes of the NLO distributions can be different from the leading order ones for the Kaluza-Klein graviton. Moreover, we study the NLO corrections to the spin correlations of the top quark pair production via the above process, and find that the corrections are small.

[en] The hemisphere soft function is calculated to order α_s². This is the first multiscale soft function calculated to two loops. The renormalization scale dependence of the result agrees exactly with the prediction from effective field theory. This fixes the unknown coefficients of the singular parts of the two-loop thrust and heavy-jet mass distributions. There are four such coefficients, for 2 event shapes and 2 color structures, which are shown to be in excellent agreement with previous numerical extraction. The asymptotic behavior of the soft function has double logs in the C_FC_A color structure, which agree with nonglobal log calculations, but also has subleading single logs for both the C_FC_A and C_FT_Fn_f color structures. The general form of the soft function is complicated, does not factorize in a simple way, and disagrees with the Hoang-Kluth ansatz. The exact hemisphere soft function will remove one source of uncertainty on the α_s fits from e⁺e^- event shapes.

[en] We present the complete calculations of the forward-backward asymmetry (A_FB) and the total cross section of top quark pair production induced by dimension-six four quark operators at the Tevatron up to O(α_s²/Λ²). Our results show that next-to-leading order QCD corrections can change A_FB and the total cross section by about 10%. Moreover, next-to-leading order QCD corrections reduce the dependence of A_FB and total cross section on the renormalization and factorization scales significantly. We also evaluate the total cross section and the charge asymmetry (A_C) induced by these operators at the Large Hadron Collider (LHC) up to O(α_s²/Λ²), for the parameter space allowed by the Tevatron data. We find that the value of A_C induced by these operators is much larger than standard model prediction, and LHC has potential to discover these new physics effects when the measurement precision increases.

[en] Detailed calculations of the complete O(α_s) corrections to the top-quark decay widths Γ(t→q+V) with V=g, γ, Z, and q=u, c are presented. Besides describing in detail the calculations in our previous work [Phys. Rev. Lett. 102, 072001 (2009)], we also include the mixing effects of the flavor-changing neutral-current operators for t→q+γ and t→q+Z, which were not considered previously. We show that the mixing effects can either be large or small depending on the values of various anomalous couplings and thereby increase or decrease the branching ratios for t→q+γ and t→q+Z.