Using the strong electromagnetic fields in peripheral heavy ion collisions gives rise to a number of interesting possibilities of applications in both photon-photon and photon-hadron physics. We look at the theoretical foundations of the equivalent photon approximation and the specific problems in the heavy ion case. The interesting physics processes that can be studied in this way are outlined...

I compute the leading color-octet contributions to the process γ + p → J/ψ + γ (+X) within the non-relativistic QCD (NRQCD) factorization formalism. In the color-singlet model, J/ψ + γ can only be produced when the photon interacts through its structure function, while the color-octet mechanism allows for production of J/ψ+γ via direct photon-gluon fusion. Resolved photon processes can be easil...

An overview of recent high-pT hadron and photon measurements at RHIC is presented with a focus on the evolution of hadron/photon production from intermediate pT (. 5 GeV/c) to high pT (> 10 GeV/c). Addressed topics include single high-pT hadron production, azimuthal anisotropy of π production, di-jet modification at intermediate pT and inclusive photon-hadron correlations. The understanding of ...

I discuss the current status of the comparison between theoretical predictions and experimental data, relevant to the production of open charm and bottom quarks in photon-hadron and photon-photon collisions. I advocate the use of a formalism that matches fixed-order computations to resummed computations in order to make firm statements on heavy flavour production as described by perturbative QCD.

The event structure associated with the production of massive photon pairs is studied to O(α 2 α s). The cross sections for two photon and two photon plus one jet events are given. The Dalitz plot structure of events with two photons and a jet is also presented. These distributions will provide checks on our understanding of the production mechanisms for massive photon pairs, a signal thought t...

Due to coherence, there are strong electromagnetic fields of short duration in very peripheral heavy ion collisions. They give rise to photon-photon and photon-nucleus collisions with high flux up to an invariant mass region hitherto unexplored experimentally. Photon-photon and photon-hadron physics at various invariant mass scales are discussed. Due to the very strong electromagnetic fields th...

We present the first completely analytical computationof the full differentialγ-γ pair production rate fromcompact radiation fields, exact to 2nd order QED, and use this result to investigate the validity of previously known approximations.

A dual picture between perturbative QCD and resonance production is exploited to describe non-diffractive meson pair production near threshold in 77 annihilation. Submitted to Physical Review Letters * Work supported in part by the Department of Energy, contract DE-AC03-76SF00515. In quantum chromodynamics, hadron production in 77 annihilation is initiated by the coupling of the incident photon...

Jet and particle production have been studied in collisions of quasi-real photons collected during the LEP2 program. OPAL and DELPHI report good agreement of NLO perturbative QCD with the measured differential di-jet cross sections, which reach a mean transverse energy of the di-jet system of 25GeV. L3, on the other hand, finds drastic disagreement of the same calculation with single jet produc...

The heavy neutral Higgs bosons H, A in the minimal supersymmetric extension of the Standard Model can be produced as single resonances at high-energy γγ colliders. We have studied the prospects of the search for these particles in b ¯ b and neutralino-pair final states. The Higgs bosons can be found with masses up to 70–80% of the initial e ± e − collider energy for medium values of tgβ, i.e. i...