Abstract
The higher-order quantum electrodynamics (QED) effect for vacuum pair production has been searched without success since 1954. In this paper, we show that the combined world-wide data of lepton pair vacuum production is about 20% smaller than the latest lowest order QED calculation with a 5.2 sigma-level of significance and is consistent with the corresponding higher-order QED result. We claim the discovery of higher-order effect for the QED pair production, which settles the dust of previous debates for several decades. The verification of higher-order QED effect is a fundamental scientific problem, which is an important milestone towards the nonperturbative and nonlinear regime of QED vacuum.
Highlights
Due to the large charge carried by the heavy ion, the effect coupling Zα (∼ 0.6 for gold and lead) for the production process is close to 1
All the measurements are found to be in good agreement with the calculations of equivalent photon approximation approach, which are identical to the lowest order quantum electrodynamics (QED) results for cross section estimation
The coupling constant in these collisions is in perturbative limit (Zα → 0), which provides excellent baseline to test the validity of lowest order QED
Summary
The total cross section of vacuum pair production in lowest order due to the Coulomb fields of two colliding nuclei has been carried out for the first time by Landau and Lifshitz [11]. In the lowest order QED calculations, the internal photon radiation is not considered, which leads to the absence of tail in the transverse momentum distributions of the produced vacuum pairs. Estimated the QED showering effect in a Sudakov formalism, which qualitatively described the notable tail in acoplanarity distributions observed by ATLAS [43] To include this effect, the lowest-order QED calculations are provided as input into Pythia (version 8.305 [44, 45]) for QED showering. For a fair comparison with experimental data, this effect should be considered to correctly estimated the acceptance in the measured kinematic region
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