Coherent Photons and Pomerons in Heavy Ion Collisions

Abstract

Ultrarelativistic heavy ion beams carry large electromagnetic and strong absorptive fields, allowing exploration of a variety of physics. Two-photon, photon-Pomeron, and double Pomeron interactions can probe a huge variety of couplings and final states. RHIC will be the first heavy ion accelerator energetic enough to produce hadronic final states via coherent couplings. Virtual photons from the nuclear EM fields can interact in two-photon interactions, which can be exploited to study many particle spectroscopy and QCD topics. Because the photon flux scales as $Z^2$, Two-photon luminosities are large up to an energy of about γ\hbar c/R~ 3 GeV/c. Photon-Pomeron interactions are sensitive to how different vector mesons, including the $J/ψ$, interact with nuclear matter. $PP$ collisions rates are sensitive to the range of the Pomeron. Signals can be separated from backgrounds by using cuts on final state isolation (rapidity gaps) and $p_\perp$. We present Monte Carlo studies of different backgrounds, showing that representative signals can be extracted with good rates and signal to noise ratios.