相关论文: The Drell-Hearn-Gerasimov Sum-Rule at Polarized HE…
The status of the Gerasimov-Drell-Hearn sum rules for polarized inclusive photo-production on nucleons is reviewed. It is shown that results from currently available data compare favorably with an estimate based on an extended current…
The Drell-Hearn-Gerasimov sum-rule is really two sum-rules: one for each of the valence and the sea/glue contributions to the nucleon wavefunction. The convergence of these sum-rules follows from the Froissart bound for spin dependent…
The operation of HERA with polarized proton and electron beams will allow to study a wide variety of observables in polarized electron-proton collisions at $\sqrt s=300$ GeV. The physics prospects of this project have been elaborated in…
Di-jet photoproduction in polarized ep collisions at HERA is studied as a possible tool to determine the parton content of circularly polarized photons. The concept of the `effective parton density' approximation is extended to the…
We study photoproduction reactions in a polarized ep collider mode of HERA at sqrt(s)=298 GeV. We examine the sensitivity of the cross sections and their asymmetries to the proton's polarized gluon distribution and to the completely unknown…
Photoproduction spin sum-rules offer a new window on the spin structure of the nucleon that complements the information we can learn from polarised deep inelastic scattering experiments. We review the theory and present status of the…
We present estimates of possible data on spin-dependent asymmetries in inclusive scattering of high energy polarized electrons by high energy polarized protons at HERA, including statistical errors, and discuss systematic uncertainties. We…
The physics scope of polarized nucleon-nucleon collisions originating from an internal polarized target in the HERA proton beam is summarized. Based on 240 pb^{-1} integrated luminosity at 40 GeV c.m. energy, statistical sensitivities are…
Results of our next-to-leading order analytic calculation for longitudinally polarized photoproduction of heavy quarks are presented. Certain differential cross sections and the corresponding asymmetries are computed for energy ranges…
We study photoproduction of jets and single-inclusive hadrons in a polarized ep collider mode of HERA at sqrt(s)=300 GeV, examining the sensitivity of the cross sections and their asymmetries to the proton's polarized gluon distribution and…
We consider the possibility of a direct determination of the polarized gluon density in the proton using charm production with polarized beams at HERA. We study total cross sections and distributions at leading order using different…
The Gerasimov-Drell-Hearn sum rule and related dispersive integrals connect real and virtual Compton scattering to inclusive photo- and electroproduction. Being based on universal principles as causality, unitarity, and gauge invariance,…
We present a NLO study of inclusive polarized prompt photon production in a conceivable fixed target $pp$ mode of HERA with longitudinally polarized protons at $\sqrt{s}=39$ GeV. We analyze the sensitivity of the corresponding double spin…
The physics scope of a possible future experiment utilizing an internal polarized nucleon target in the HERA proton beam is discussed. By measuring single spin asymmetries in inclusive particle production at 820~GeV beam energy the…
The main goals of `spin physics' are recalled, and some theoretical and phenomenological aspects of longitudinally polarized deep inelastic scattering and other hard processes are reviewed. The spin dependent parton densities of protons and…
Hadron properties are modified when the hadron is embedded in a nuclear medium. Here we discuss the Gerasimov-Drell-Hearn, GDH, sum rule for polarised photoproduction from a polarised nucleon within a polarised nuclear target. Strong…
Several important and unique measurements, within the standard model and of possible physics beyond it, could be made with {\em polarized HERA} in which both the proton and the electron beams are polarized. With a $\sim$820 GeV proton beam…
We study various conceivable photoproduction reactions in a polarized ep collider mode of HERA with respect to their sensitivity to the proton's polarized gluon distribution. A special emphasis is put on the `resolved' part of the cross…
We discuss a possibility to measure the spin-dependent part of the forward Compton scattering amplitude through interference effects of the Bethe-Heitler and virtual Compton scattering mechanisms in photoproduction of e+e- pairs at small…
We study photoproduction of jets and heavy flavors in a polarized collider mode of HERA at $\sqrt{S}= 298$ GeV. We examine the sensitivity of the cross sections and their asymmetries to the proton's polarized gluon distribution and to the…