paper

Neutron contribution to nuclear DVCS asymmetries

arXiv:0801.3235 · doi:10.1103/PhysRevC.78.025211

Abstract

Using a simple model for nuclear GPDs, we study the role of the neutron contribution to nuclear DVCS observables. As an example, we use the beam-spin asymmetry A_{LU}^A measured in coherent and incoherent DVCS on a wide range of nuclear targets in the HERMES and JLab kinematics. We find that at small values of the momentum transfer t, A_{LU}^A is dominated by the coherent-enriched contribution, which enhances A_{LU}^A compared to the free proton asymmetry A_{LU}^p, A_{LU}^A(ϕ)/A_{LU}^p(ϕ)=1.8-2.2. At large values of t, the nuclear asymmetry is dominated by the incoherent contribution and A_{LU}^A/(ϕ)A_{LU}^p(ϕ)=0.66-0.74. The deviation of A_{LU}^A(ϕ)/A_{LU}^p(ϕ) from unity at large t is a result of the neutron contribution, which gives a possibility to constain neutron GPDs in incoherent nuclear DVCS. A similar trend is expected for other DVCS asymmetries.

24 pages, 7 figures

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