Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
; China Ctr Adv Sci & Technol, World Lab, Beijing 100080, Peoples R China
; Inst Atom Energy, Beijing 102413, Peoples R China
; Natl Lab Heavy Ion Accelerator Lanzhou, Ctr Theoret Nucl Phys, Lanzhou 730000, Peoples R China
; Chinese Acad Sci, Inst Theoret Phys, Beijing 100080, Peoples R China
The low-lying isovector dipole strengths in the neutron-rich nuclei Ne-26 and Ne-28 are investigated in the quasiparticle relativistic random phase approximation. Nuclear ground-state properties are calculated in an extended relativistic mean field theory plus Bardeen-Cooper-Schrieffer (BCS) method where the contribution of the resonant continuum to pairing correlations is properly treated. Numerical calculations are tested in the case of isovector dipole and isoscalar quadrupole modes in the neutron-rich nucleus O-22. It is found that in the present calculation, low-lying isovector dipole strengths at E-x < 10 MeV in nuclei Ne-26 and Ne-28 exhaust about 4.9% and 5.8% of the Thomas-Reiche-Kuhn dipole sum rule, respectively. The centroid energy of the low-lying dipole excitation is located at 8.3 MeV in Ne-26 and 7.9 MeV in Ne-28.