Tomography of ultrarelativistic nuclei with polarized photon-gluon collisions.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36598973.
- Also identified by DOI 10.1126/sciadv.abq3903 and PMC identifier 9812379.
- Licence recorded as CC BY-NC.
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Abstract
A linearly polarized photon can be quantized from the Lorentz-boosted electromagnetic field of a nucleus traveling at ultrarelativistic speed. When two relativistic heavy nuclei pass one another at a distance of a few nuclear radii, the photon from one nucleus may interact through a virtual quark-antiquark pair with gluons from the other nucleus, forming a short-lived vector meson (e.g., ρ<sup>0</sup>). In this experiment, the polarization was used in diffractive photoproduction to observe a unique spin interference pattern in the angular distribution of ρ<sup>0</sup> → π<sup>+</sup>π<sup>-</sup> decays. The observed interference is a result of an overlap of two wave functions at a distance an order of magnitude larger than the ρ<sup>0</sup> travel distance within its lifetime. The strong-interaction nuclear radii were extracted from these diffractive interactions and found to be 6.53 ± 0.06 fm (<sup>197</sup>Au) and 7.29 ± 0.08 fm (<sup>238</sup>U), larger than the nuclear charge radii. The observable is demonstrated to be sensitive to the nuclear geometry and quantum interference of nonidentical particles.