Bounding elastic photon-photon scattering at s≈1 MeV using a laser-plasma platform
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Author(s)
Type
Journal Article
Abstract
We report on a direct search for elastic photon-photon scattering using x-ray and 𝛾 photons from a laser-plasma
based experiment. A 𝛾 photon beam produced by a laser wakeeld accelerator provided a broadband 𝛾 spectrum
extending to above 𝐸𝛾 = 200 MeV. These were collided with a dense x-ray eld produced by the emission from
a laser heated germanium foil at 𝐸𝑥 ≈ 1.4 keV, corresponding to an invariant mass of √𝑠 = 1.22 ± 0.22 MeV. In
these asymmetric collisions elastic scattering removes one x-ray and one high-energy 𝛾 photon and outputs two
lower energy 𝛾 photons. No changes in the 𝛾 photon spectrum were observed as a result of the collisions allowing
us to place a 95% upper bound on the cross section of 1.5 × 1015 μb. Although far from the QED prediction, this
represents the lowest upper limit obtained so far for √𝑠 ≲ 1 MeV.
based experiment. A 𝛾 photon beam produced by a laser wakeeld accelerator provided a broadband 𝛾 spectrum
extending to above 𝐸𝛾 = 200 MeV. These were collided with a dense x-ray eld produced by the emission from
a laser heated germanium foil at 𝐸𝑥 ≈ 1.4 keV, corresponding to an invariant mass of √𝑠 = 1.22 ± 0.22 MeV. In
these asymmetric collisions elastic scattering removes one x-ray and one high-energy 𝛾 photon and outputs two
lower energy 𝛾 photons. No changes in the 𝛾 photon spectrum were observed as a result of the collisions allowing
us to place a 95% upper bound on the cross section of 1.5 × 1015 μb. Although far from the QED prediction, this
represents the lowest upper limit obtained so far for √𝑠 ≲ 1 MeV.
Date Issued
2025-02
Date Acceptance
2025-01-07
Citation
Physics Letters B: Nuclear Physics and Particle Physics, 2025, 861
ISSN
0370-2693
Publisher
Elsevier
Journal / Book Title
Physics Letters B: Nuclear Physics and Particle Physics
Volume
861
Copyright Statement
© 2025 The Author(s). Published by Elsevier B.V. Funded by SCOAP³. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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Publication Status
Published
Article Number
139247
Date Publish Online
2025-01-10