We investigate the inclusive production of prompt J/ψ mesons in polarized hadron-hadron, photon-hadron, and photon-photon collisions in the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD) providing all contributing partonic cross sections in analytic form. In the case of photoproduction, we also include the resolved-photon contributions. We present numerical results ap...

Electron-positron pair production via real and virtual photons is signi cant to the design of linear colliders, especially in the deep quantum regime (i.e., beamstrahlung parameter >> 1). In this regime, pair production via a virtual photon (the trident process) can become comparable in rate to pair production via a real beamstrahlung photon. We derive characteristics of the e+epairs produced v...

In this talk I present a summary of some of the discussions at the conference on various topics in Photon physics, selected with a view to give a theorist's perspective, of the current status and future prospects, of the developments in the field. After discussing some of the recent theoretical developments in the subject of Photon Structure function, I will focus on what the photon has helped ...