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Experimental input for $e^+e^-$ for $a_{\mu}$ light-by-light
by Y. P. Guo for BESIII Collaboration
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Submission summary
| Authors (as registered SciPost users): | Yuping Guo |
| Submission information | |
|---|---|
| Preprint Link: | scipost_201811_00012v1 (pdf) |
| Date submitted: | 2018-11-11 01:00 |
| Submitted by: | Guo, Yuping |
| Submitted to: | SciPost Physics Proceedings |
| Proceedings issue: | The 15th International Workshop on Tau Lepton Physics (TAU2018) |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Experimental |
Abstract
The anomalous magnetic momentum of the muon, $a_{\mu}$, has been measured and calculated with a precision up to $~0.5$ ppm, but there is a 3 to 4 standard deviations between these two values. The uncertainty in the calculation is dominated by the hadronic part, including the hadronic vacuum polarization and the hadronic light-by-light. The meson transition form factors and the helicity amplitudes can be used as input or constraint to the calculation of the hadronic light-by-light contribution. Latest experimental studies of the transition form factors of $\pi^{0}$, $\eta$, and $\eta^{\prime}$ and the cross-section of $\gamma\gamma^{*}\to\pi^+pi^-$ from $e^+e^-$ collider are presented.
Current status:
Reports on this Submission
Report #1 by Gerco Onderwater (Referee 1) on 2018-12-4 (Invited Report)
- Cite as: Gerco Onderwater, Report on arXiv:scipost_201811_00012v1, delivered 2018-12-04, doi: 10.21468/SciPost.Report.701
Report
This paper reports on important new measurements in their own right, and which may assist in reducing the uncertainty in the predicted value of the anomalous magnetic moment of the muon, specifically the hadronic light-by-light one. The theoretical motivation is sketched concisely, with a more elaborate description of the essence of the experimental procedure used to extract the various form factors.
Minor changes to the content, esp. grammar, would improve the already high quality of the paper.
Requested changes
L28: "with a statistical precision of 0.54 ppm" -> that is the total uncertainty
L34: "The QED contribution is the largest one, *AND* has been calculated up to 5-loop in perturbation theory with a precision of 0.0007 ppm" -> grammar
L35: "The weak contribution is small, *IT* has been calculated to 2-loop, with the measured Higgs mass taken into account [8], and its uncertainty is well under control." -> grammar; remove 'it'
L43: "... can be related to the hadronic cross-section ..." -> which hadronic cross section? There is no THE hadronic one.
L45: "*MEAN*while the situation for the HLbL part is different."
L72: "The BEPCII is a τ-charm factory THAT works with center-of-mass (CM) energy from 2.0
73 GeV to 4.6 GeV. "
L154-162: its not clear how to interpret the chi-squared, as the values are nowhere near 1. Some notion about the number of degrees of freedom is warranted, or a statement that only relative chi^2's are used.
Author: Yuping Guo on 2018-12-05 [id 365]
(in reply to Report 1 by Gerco Onderwater on 2018-12-04)Changes have been made according to the suggestions from referee