Measurement of e+e- Momentum and Angular Distributions from Linearly Polarized Photon Collisions

Abstract

The Breit-Wheeler process which produces matter and antimatter from photon collisions is experimentally investigated through the observation of 6085 exclusive electron-positron pairs in ultraperipheral Au+Au collisions at sNN=200 GeV. The measurements reveal a large fourth-order angular modulation of cos4Δφ=(16.8±2.5)% and smooth invariant mass distribution absent of vector mesons (φ, ω, and ρ) at the experimental limit of ≤0.2% of the observed yields. The differential cross section as a function of e+e- pair transverse momentum P⊥ peaks at low value with ⟨P⊥2