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In the paper, we study the $Upsilon(1S)$ leptonic decay width $Gamma(Upsilon(1S)to ell^+ell^-)$ by using the principle of maximum conformality (PMC) scale-setting approach. The PMC adopts the renormalization group equation to set the correct momentum flow of the process, whose value is independent to the choice of the renormalization scale and its prediction thus avoids the conventional renormalization scale ambiguities. Using the known next-to-next-to-next-to-leading order perturbative series together with the PMC single scale-setting approach, we do obtain a renormalization scale independent decay width, $Gamma_{Upsilon(1S) to e^+ e^-} = 1.262^{+0.195}_{-0.175}$ keV, where the error is squared average of those from $alpha_s(M_{Z})=0.1181pm0.0011$, $m_b=4.93pm0.03$ GeV and the choices of factorization scales within $pm 10%$ of their central values. To compare with the result under conventional scale-setting approach, this decay width agrees with the experimental value within errors, indicating the importance of a proper scale-setting approach.
The Higgs boson decay channel, $Htogammagamma$, is one of the most important channels for probing the properties of the Higgs boson. In the paper, we reanalyze its decay width by using the QCD corrections up to $alpha_s^4$-order level. The principle
We present a detailed study on the properties of the free energy density at the high temperature by applying the principle of maximum conformality (PMC) scale-setting method within the effective field theory. The PMC utilizes the renormalization grou
We present a comprehensive and self-consistent analysis for the thrust distribution by using the Principle of Maximum Conformality (PMC). By absorbing all nonconformal terms into the running coupling using PMC via renormalization group equation, the
The next-to-next-to-leading order (NNLO) pQCD prediction for the $gammagamma^* to eta_c$ form factor was evaluated in 2015 using nonrelativistic QCD (NRQCD). A strong discrepancy between the NRQCD prediction and the BaBar measurements was observed. U
Decay $Upsilon(1s)togamma f_2(1270)$ is studied by an approach in which the tensor meson, $f_2(1270)$, is strongly coupled to gluons. Besides the strong suppression of the amplitude $Upsilon(1s)togamma gg, ggto f_2$ by the mass of b-quark, d-wave dom