Scale-fixed predictions for γ + ηc production in electron-positron collisions at NNLO in perturbative QCD

Yu, Huai-Min; Sang, Wen-Long; Huang, Xu-Dong; Zeng, Jun; Wu, Xing-Gang; Brodsky, Stanley J.

doi:10.1007/jhep01(2021)131

Cited by 11 publications

(10 citation statements)

References 45 publications

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“…Moreover, due to the independence on the renormalization scheme and scale, the resulting conformal series not only provides precise pQCD predictions; it also can reliably estimate the contributions from the unknown higher-order terms. The PMCs has been successfully applied to several high-energy processes [37][38][39][40][41][42][43], where the contributions from unknown higher-order terms have been estimated by using the Padé approximation approach [44][45][46].…”

Section: Introductionmentioning

confidence: 99%

Detailed Comparison of Renormalization Scale-Setting Procedures based on the Principle of Maximum Conformality

Huang¹,

Jiang²,

Ma³

et al. 2021

Preprint

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It has become conventional to simply guess the renormalization scale and choose an arbitrary range of uncertainty when making perturbative QCD (pQCD) predictions. However, this ad hoc assignment of the renormalization scale and the estimate of the size of the resulting uncertainty leads to anomalous renormalization scheme-and-scale dependences. In fact, relations between physical observables must be independent of the theorist's choice of the renormalization scheme, and the renormalization scale in any given scheme at any given order of pQCD is not ambiguous. The Principle of Maximum Conformality (PMC), which generalizes the conventional Gell-Mann-Low method for scale-setting in perturbative QED to non-Abelian QCD, provides a rigorous method for achieving unambiguous scheme-independent, fixed-order predictions for observables consistent with the principles of the renormalization group. The renormalization scale in the PMC is fixed such that all β terms are eliminated from the perturbative series and resumed into the running coupling; this procedure results in a convergent, scheme-independent conformal series without factorial renormalon divergences. The resulting relations between physical observables, such as commensurate scale relations, are independent of the choice of renormalization scheme. Although conventional renormalization scheme and scale ambiguities do not appear, a PMC prediction will of course still have some residual scale uncertainty arising from uncalculated higher-order terms. If the resulting PMC conformal series does not have sufficient convergence, the residual scale uncertainty from the unknown higher order pQCD contributions could be significant. Several variations of the PMC have been proposed to deal with ambiguities associated with the uncalculated higher order terms in the pQCD series, such as the multi-scale-setting approach (PMC), the single-scale-setting approach (PMCs), and the procedures based on "intrinsic conformality" (PMC∞). In this paper, we will give a detailed comparison of these PMC approaches by comparing their predictions for three important quantities R e + e − , Rτ , and Γ(H → b b) up to four-loop pQCD corrections. The PMC approach also determines an overall effective running coupling αs(Q) by the recursive use of the renormalization group equation, whose argument Q represents the actual momentum flow of the process. Our numerical results show that the single-scale PMCs method, which involves a somewhat simpler analysis, can serve as a reliable substitute for the full multi-scale PMCm method, and that it leads to more precise pQCD predictions with less residual scale dependence.

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Section: Introductionmentioning

confidence: 99%

Detailed Comparison of Renormalization Scale-Setting Procedures based on the Principle of Maximum Conformality

Huang¹,

Jiang²,

Ma³

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

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“…(3.3)-(3.5). To guarantee JHEP02(2023)049 our result reliable, we have also reproduced the NNLO corrections to e + e − → η c + γ process [62].…”

Section: Jhep02(2023)049 3 Phenomenological Resultsmentioning

confidence: 99%

Next-to-next-to-leading-order QCD corrections to J/ψ plus ηc production at the B factories

Huang

Gong

Wang

2023

J. High Energ. Phys.

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In this paper, we calculate the next-to-next-to-leading-order (NNLO) QCD corrections to e+e− → J/ψ + ηc at the B factories. After including the NNLO corrections, the cross section of e+e−→ J/ψ +ηc is enhanced by about 17%, and the perturbative series of the prediction shows the convergent behavior. It is also found that the contributions from bottom quark starts at the $$ {\alpha}_s^3 $$ α s 3 -order, which is about 2.4% of the total prediction. The renormalization scale μR dependence of the cross section is reduced at the NNLO level, but the prediction is sensitive to the charm quark mass mc. By considering the uncertainties caused by renormalization scale μR, charm quark mass mc and the NRQCD factorization scale μΛ, our prediction shows agreement with the BABAR and BELLE measurements within errors.

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“…Recently, there have been great advances in the calculation of high-order radiative corrections to quarkonium inclusive and exclusive production and decay [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. For many processes, the two-loop radiative corrections are significant relative to the LO results, which may substantially change the theoretical predictions [9][10][11][12][13][14]18].…”

Section: Jhep12(2021)189mentioning

confidence: 99%

Next-to-leading-order QCD corrections to a vector bottomonium radiative decay into a charmonium

Zhang

Feng

Sang

et al. 2021

J. High Energ. Phys.

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Within the framework of nonrelativistic QCD (NRQCD) factorization, we calculate the next-to-leading-order (NLO) perturbative corrections to the radiative decay Υ → ηc(χcJ) + γ. Both the helicity amplitudes and the helicity decay widths are obtained. It is the first computation for the processes involving both bottomonium and charmonium at two-loop accuracy. By employing the Cheng-Wu theorem, we are able to convert most of complex-valued master integrals (MIs) into real-valued MIs, which makes the numerical integration much efficient. Our results indicate the $$ \mathcal{O}\left({\alpha}_s\right) $$ O α s corrections are moderate for ηc and χc2 production, and are quite marginal for χc0 and χc1 production. It is impressive to note the NLO corrections considerably reduce the renormalization scale dependence in both the decay widths and the branching fractions for χcJ, and slightly improve that for ηc. With the NRQCD matrix elements evaluated via the Buchmüller-Tye potential model, we find the decay width for ηc production is one-order-of-magnitude larger than χcJ production, which may provide a good opportunity to search for Υ → ηc + γ in experiment. In addition, the decay width for χc1 production is several times larger than those for χc0,2. Finally, we find the NLO NRQCD prediction for the branching fraction of Υ → χc1 + γ is only half of the lower bound of the experimental data measured recently by Belle. Moreover, there exists serious contradiction between theory and experiment for Υ → ηc + γ. The discrepancies between theory and experiment deserve further research efforts.

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Scale-fixed predictions for γ + ηc production in electron-positron collisions at NNLO in perturbative QCD

Cited by 11 publications

References 45 publications

Detailed Comparison of Renormalization Scale-Setting Procedures based on the Principle of Maximum Conformality

Detailed Comparison of Renormalization Scale-Setting Procedures based on the Principle of Maximum Conformality

Next-to-next-to-leading-order QCD corrections to J/ψ plus ηc production at the B factories

Next-to-leading-order QCD corrections to a vector bottomonium radiative decay into a charmonium

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