| The properties of neutron star matter in strong magnetic fields are studied in the framework of the relativistic mean-field theory (RMFT).We mainly studied the effects of strong magnetic fields on the equation of state(EOS), the structure and distribution of particles in neutron stars. At last, we studied the effects of strong magnetic fields on the direct URCA process for nucleons in neutron stars. For the purpose of comparison, we investigate in two different forms of magnetic field which are density dependence and uniform magnetic field respectively. Calculation results express that if the interior field is on the same order as the surface field (1012 G) currently observed, the field's influences on the EOS and structure and distribution of particles in neutron stars are negligible. If the interior field (1018 G) predicted by scalar virial theorem is correct, the field's influences on the properties of neutron stars should be considerable. Besides, we also discuss the differences between the two cases with and without the anomalous magnetic moments when we investigate the effects of strong magnetic fields on the EOS and the distribution of particles.First, we investigate the effects of strong magnetic fields including the anomalous magnetic moments on the EOS of neutron stars. Calculation results show that the EOS gradually become stiffer as the enhancement of the field when the anomalous magnetic moments is not considered.For density dependence magnetic field, this phenomenon is obvious in the ranges of high density. For uniform magnetic, this phenomenon is obvious in the ranges of low density. We find that the EOS of neutron stars do not change any more when the anomalous magnetic moments is considered, which means the anomalous magnetic moments almost has no effects on the EOS. Second, we investigate the effects of strong magnetic fields on the structure of neutron stars. As the anomalous magnetic moments almost has no effects on the EOS, we do not consider the cases with it. Calculation results show that density dependence magnetic field makes the neutron stars become looser while the uniform magnetic field makes the neutron stars become more compact.Then we investigate the effects of strong magnetic fields on the distribution of particles in neutron stars. By comparison with the field free case, we find that the density dependence magnetic field does not have great effects on the distribution of particles while the uniform case has very obvious effect on the distribution of particles. In the uniform magnetic field case, the proton fraction increase gradually with the enhancement of the magnetic field. When the field is very strong the proton fraction will exceed the neutron fraction and the whole star matter will convert into proton-rich matter. However, the introduction of the anomalous magnetic moments will suppress this process and lead the whole star matter into neutron-rich matter.Finally, we investigate the effects of strong magnetic fields on the direct URCA process which is closely related to the cooling of neutron stars. Calculation results show that the direct URCA process in the strong magnetic field can occur at any density of the neutron stars, which is different from the case that the magnetic field is absent. Besides, the neutrino emissivity increases obviously with the enhancement of the magnetic fields.
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