The origin of proton mass from J/$${\Psi }$$ Ψ photo-production data
Abstract The trace of the stress tensor characterizes the transformation of a theory under rescaling. In quantum chromodynamics (QCD), this trace contains contributions from the bare masses of the quarks and also from a purely quantum effect, called the QCD trace anomaly. It affects all masses in th...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
SpringerOpen
2020-06-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | http://link.springer.com/article/10.1140/epjc/s10052-020-8057-9 |
| Summary: | Abstract The trace of the stress tensor characterizes the transformation of a theory under rescaling. In quantum chromodynamics (QCD), this trace contains contributions from the bare masses of the quarks and also from a purely quantum effect, called the QCD trace anomaly. It affects all masses in the theory. We present an estimation of the QCD trace anomaly from the near-threshold $$\hbox {J}/{\Psi }$$ J/Ψ photo-production data of the GlueX experiment, at JLab. We apply a vector meson dominance model to describe the photo-production of $$\hbox {J}/{\Psi }$$ J/Ψ and a running strong coupling which includes the nonperturbative effects in the low $$\mu ^2$$ μ2 region. Despite the large uncertainty, we find that the experimental data favors a small value of the trace anomaly parameter $$b=0.07\pm 0.17$$ b=0.07±0.17 . We report the resulting proton mass decompositions at $$\mu ^2=0.41\hbox { GeV}^2$$ μ2=0.41GeV2 and $$\mu ^2=4\hbox { GeV}^2$$ μ2=4GeV2 . |
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| ISSN: | 1434-6044 1434-6052 |