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

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:
 [1] ;  [2] ;  [3] ;  [4]
  1. Guizhou Minzu Uiv., Guiyang (People's Republic of China); Chongqing Univ., Chongqing (People's Republic of China)
  2. Chongqing Univ., Chongqing (People's Republic of China)
  3. Southwest Univ., Chongqing (People's Republic of China)
  4. Stanford Univ., Stanford, CA (United States)
Publication Date:
Grant/Contract Number:
11547010; 11625520; 11705033; 11605144; AC02-76SF00515; SLAC-PUB-17247; 2016GZ42963; KY [2016]028; KY[2017]067
Type:
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 97; Journal Issue: 9; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
OSTI Identifier:
1458417

Wang, Sheng -Quan, Wu, Xing -Gang, Sang, Wen -Long, and Brodsky, Stanley J. Solution to the γγ*→ηc puzzle using the principle of maximum conformality. United States: N. p., Web. doi:10.1103/physrevd.97.094034.
Wang, Sheng -Quan, Wu, Xing -Gang, Sang, Wen -Long, & Brodsky, Stanley J. Solution to the γγ*→ηc 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. 2018. "Solution to the γγ*→ηc puzzle using the principle of maximum conformality". United States. doi:10.1103/physrevd.97.094034. https://www.osti.gov/servlets/purl/1458417.
@article{osti_1458417,
title = {Solution to the γγ*→ηc 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}
}