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Title: Solution to the γ γ * η c puzzle using the principle of maximum conformality

Abstract

Here, the next-to-next-to-leading-order (NNLO) pQCD prediction for the γγ* → η c form factor was evaluated in 2015 using nonrelativistic QCD (NRQCD). A strong discrepancy between the NRQCD prediction and the BABAR measurements was observed. Until now there has been no solution for this puzzle. In this paper, we present a NNLO analysis by applying the Principle of Maximum Conformality (PMC) to set the renormalization scale. By carefully dealing with the light-by-light diagrams at the NNLO level, the resulting high precision PMC prediction agrees with the BABAR measurements within errors, and the conventional renormalization scale uncertainty is eliminated. The PMC is consistent with all of the requirements of the renormalization group, including scheme-independence. The application of the PMC thus provides a rigorous solution for the γγ* → η c form factor puzzle, emphasizing the importance of correct renormalization scale-setting. The results also support the applicability of NRQCD to hard exclusive processes involving charmonium.

Authors:
; ; ;
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1439733
Alternate Identifier(s):
OSTI ID: 1458417
Grant/Contract Number:  
[AC02-76SF00515; SLAC-PUB-17247; 2016GZ42963; KY [2016]028; KY[2017]067; 11547010; 11625520; 11705033; 11605144]
Resource Type:
Published Article
Journal Name:
Physical Review D
Additional Journal Information:
[Journal Name: Physical Review D Journal Volume: 97 Journal Issue: 9]; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Wang, Sheng-Quan, Wu, Xing-Gang, Sang, Wen-Long, and Brodsky, Stanley J. Solution to the γ γ * → η c puzzle using the principle of maximum conformality. United States: N. p., 2018. Web. doi:10.1103/PhysRevD.97.094034.
Wang, Sheng-Quan, Wu, Xing-Gang, Sang, Wen-Long, & Brodsky, Stanley J. Solution to the γ γ * → η c puzzle using the principle of maximum conformality. United States. doi:10.1103/PhysRevD.97.094034.
Wang, Sheng-Quan, Wu, Xing-Gang, Sang, Wen-Long, and Brodsky, Stanley J. Thu . "Solution to the γ γ * → η c puzzle using the principle of maximum conformality". United States. doi:10.1103/PhysRevD.97.094034.
@article{osti_1439733,
title = {Solution to the γ γ * → η c puzzle using the principle of maximum conformality},
author = {Wang, Sheng-Quan and Wu, Xing-Gang and Sang, Wen-Long and Brodsky, Stanley J.},
abstractNote = {Here, the next-to-next-to-leading-order (NNLO) pQCD prediction for the γγ* → ηc form factor was evaluated in 2015 using nonrelativistic QCD (NRQCD). A strong discrepancy between the NRQCD prediction and the BABAR measurements was observed. Until now there has been no solution for this puzzle. In this paper, we present a NNLO analysis by applying the Principle of Maximum Conformality (PMC) to set the renormalization scale. By carefully dealing with the light-by-light diagrams at the NNLO level, the resulting high precision PMC prediction agrees with the BABAR measurements within errors, and the conventional renormalization scale uncertainty is eliminated. The PMC is consistent with all of the requirements of the renormalization group, including scheme-independence. The application of the PMC thus provides a rigorous solution for the γγ* → ηc form factor puzzle, emphasizing the importance of correct renormalization scale-setting. The results also support the applicability of NRQCD to hard exclusive processes involving charmonium.},
doi = {10.1103/PhysRevD.97.094034},
journal = {Physical Review D},
number = [9],
volume = [97],
place = {United States},
year = {2018},
month = {5}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1103/PhysRevD.97.094034

Citation Metrics:
Cited by: 3 works
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Figures / Tables:

FIG. 1 FIG. 1: The PMC scale of the NNLO TFF F (Q2) versus Q2. The conventional choice of scale µr = µQ is presented as a comparison.

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Works referenced in this record:

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    Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.