Sheng-Quan Wang

Application of the Principle of Maximum Conformality to the Top-Quark Charge Asymmetry at the LHC

The principle of maximum conformality (PMC) provides a systematic and process-independent method to derive renormalization scheme- and scale-independent fixed-order pQCD predictions. By Brodsky and Wu [Phys. Rev. D 85, 114040 (2012)1, we studied the top-quark charge asymmetry at the Tevatron. By applying the PMC, we have shown that the large discrepancies for the top-quark charge asymmetry between the Standard Model estimate and the CDF and DO data are greatly reduced. In the present paper, with the help of the Bernreuther-Si program, we present a detailed PMC analysis on the top-quark pair production up to next-to-next-to-leading-order level at the LHC. After applying PMC scale setting, the pQCD prediction for the top-quark charge asymmetry at the LHC has very small scale uncertainty; e.g. A(C broken vertical bar 7) (TeV;PMC) = (1.15(-0.03)(+0.01))%, A(C broken vertical bar 8) (TeV;PMC) = (1.03(+0.00)(+0.01))% and A(C broken vertical bar 14) (TeV;PMC) = (0.62(-0.02)(+0.00))%. The corresponding predictions using conventional scale setting are: A(C broken vertical bar 7) (TeV;PMC) = (1.23(-0.14)(+0.14))% A(C broken vertical bar 8) (TeV;Conv) = (1.11(-0.13)(+0.17))% and A(C broken vertical bar 14) (TeV;Conv) = (0.67(-0.05)(+0.05))%. In these predictions, the scale errors, are predicted by varying the initial renormalization and factorization scales in the ranges mu(init)(r) is an element of [m(t) /2,2m(t)] and mu(f) [m(t) / 2,2m(t)]. The PMC predictions are also in better agreement with the available ATLAS and CMS data. In addition, we have calculated the top-quark charge asymmetry assuming several typical cuts on the top-pair invariant mass M-t (t) over bar. For example, assuming M-t (t) over bar > 0.5 TeV and mu(f) = mu(init)(r) = m(t), we obtain A(C broken vertical bar 7) (TeV;PMC) = 2.67%, A(C broken vertical bar 8) (TeV;PMC) = 2.39%, and A(C broken vertical bar 14) (TeV;PMC) = 1.28%.

Reanalysis of the BFKL Pomeron at the next-to-leading logarithmic accuracy

A bstractWe apply the principle of maximum conformality (PMC) to the Balitsky-Fadin-Kuraev-Lipatov (BFKL) Pomeron intercept at the next-to-leading logarithmic (NLL) accuracy. The PMC eliminates the conventional renormalization scale ambiguity by absorbing the non-conformal {βi}-terms into the running coupling, and a more accurate pQCD estimation can be obtained. After PMC scale setting, the QCD perturbative convergence can be greatly improved due to the elimination of renormalon terms in pQCD series, and the BFKL Pomeron intercept has a weak dependence on the virtuality of the reggeized gluon. For example, by taking the Fried-Yennie gauge, we obtain

Reanalysis of the Higher Order Perturbative QCD corrections to Hadronic

\omega_{\mathrm{MOM}}^{\mathrm{PMC}}

Z

(Q2, 0) ∈ [0.149, 0.176] for Q2 ∈ [1, 100] GeV2. This is a good property to apply to the high-energy phenomenology. Further more, to compare with the data, it is found that the physical MOM-scheme is more reliable than the

Decays using the Principle of Maximum Conformality

\overline{\mathrm{MS}}

The Higgs boson inclusive decay channels \(H \rightarrow b\bar{b}\) and \(H \rightarrow gg\) up to four-loop level

-scheme. The MOM-scheme is gauge dependent, which can also be greatly suppressed after PMC scale setting. We discuss the MOM-scheme gauge dependence for the Pomeron intercept by adopting three gauges, i.e. the Landau gauge, the Feynman gauge and the Fried-Yennie gauge, and we obtain

QCD corrections to the

\omega_{\mathrm{MOM}}^{\mathrm{PMC}}

B_c

(Q2 = 15 GeV2, 0) =

to charmonia semileptonic decays

0.166_{-0.017}^{+0.010 }

QCD improved electroweak parameter ρ

; i.e. about 10% gauge dependence is observed. We apply the BFKL Pomeron intercept to the photon-photon collision process, and compare the theoretical predictions with the data from the OPAL and L3 experiments.