Coulomb nuclear interference effect in dipion production in ultraperipheral heavy ion collisions

We study exclusive pi(+)pi(-) pair production near rho(0) resonance peak in ultraperipheral heavy ion collisions. A pion pair can either be produced via two photon fusion process or from the decay of rho(0) in photon-nuclear reaction. At very low pair transverse momentum, the electromagnetic and nuclear amplitudes become comparable. We show that the Coulomb nuclear interference amplitude gives rise to sizable cos phi and cos 3 phi azimuthal asymmetries, which can be used to constrain the phase of the dipole-nucleus scattering amplitude.

Automated summary

We investigate exclusive pi(+)pi(-) pair production near the rho(0) resonance peak in ultraperipheral heavy ion collisions. At very low pair transverse momentum, the Coulomb nuclear interference amplitude leads to significant azimuthal asymmetries in cos phi and cos 3 phi, which can be utilized to restrict the phase of the dipole-nucleus scattering amplitude.