Quantum Interferometry in ρ Production in Ultra-Peripheral Heavy Ion Collisions

In ρ photoproduction in ultra-peripheral heavy ion collisions, either ion can be the photon emitter or the target. The two possibilities are indistinguishable, and they should be able to interfere, reducing rho production at low transverse momentum, pT < h̄/〈b〉, where 〈b〉 is the median impact parameter. The two ρ production points are separated by 〈b〉 ≈ 18−46 fm, while the ρ decay before travelling 1 fm. The two decay points are well separated in spacetime, so the decays proceed independently and any interference must involve the final state ππ. This requires a non-local wave function. Quantum Interferometry in ρ Production in Ultra-Peripheral Heavy Ion Collisions 2