Bounding elastic photon-photon scattering at $\sqrt{s}≈$ 1 MeV using a laser-plasma platform

Watt, R.; Pérez-Callejo, G.; Astbury, S.; Underwood, C.; Murphy, C. D.; Zepf, M.; Roeder, F.; Rajeev, P. P.; Spindloe, C.; Alejo, A.; Hatfield, P.; Gerstmayr, E.; Wu, W.; Dannheim, D.; King, B.; Morton, J.; Gregory, C.; Streeter, M. J. V.; Samarin, G. M.; Sarri, G.; Steinke, S.; Thomas, A. G. R.; Colgan, C.; Roedel, C.; Rose, S. J.; Harsh, H.; Baird, C.; Katzir, Y.; Hollatz, D.; Osterhoff, J.; Mangles, S. P. D.; Kettle, B.; Seidel, A.; Salgado, F. C.; Campbell, M.; Nurnberg, A.; Põder, K.; Bohlen, S.; Hinojosa, J.

Preprint

PUBDB-2025-00404

Bounding elastic photon-photon scattering at $\sqrt{s}≈$ 1 MeV using a laser-plasma platform

Watt, R. ; Kettle, B. ; Gerstmayr, E. ; King, B. (Corresponding author)Extern* ; Alejo, A. ; Astbury, S. ; Baird, C. ; Bohlen, S.DESY* ; Campbell, M. ; Colgan, C. ; Dannheim, D. ; Gregory, C. ; Harsh, H. ; Hatfield, P. ; Hinojosa, J. ; Hollatz, D. ; Katzir, Y. ; Morton, J. ; Murphy, C. D. ; Nurnberg, A. ; Osterhoff, J. ; Pérez-Callejo, G. ; Põder, K. ; Rajeev, P. P. ; Roedel, C. ; Roeder, F. ; Salgado, F. C. ; Samarin, G. M. ; Sarri, G. ; Seidel, A. ; Spindloe, C. ; Steinke, S. ; Streeter, M. J. V. ; Thomas, A. G. R. ; Underwood, C. ; Wu, W. ; Zepf, M. ; Rose, S. J. ; Mangles, S. P. D.

2025

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Report No.: arXiv:2407.12915

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 wakfield accelerator provided a broadband 𝛾 spectrum extending to above 𝐸𝛾 = 200 MeV. These were collided with a dense x-ray field 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.

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