原子核内光子的有效质量

Effective Photon Mass in Finite Nuclei

研究了无限大核子费密气体和有限原子核内电磁场的性质 .由于电荷密度算符的基态期待值在核子费密气体内不为零 ,电荷的U(1)定域规范对称性自发破缺 .微扰计算光子的自能可知在核子费密气体内光子有效质量与质子的标量密度有关 .在饱和密度 ρ0 =0 .16fm-3 的正常核物质中 ,光子有效质量为 5 .4 2MeV ;在2 3 8U原子核的表面处 ,光子有效质量约为 2 .0MeV .在这一问题中 ,这两种方法是等价的 .同时文章指出正是由于原子核表面处有质量光子的两体衰变导致在低能2 3 8U +2 3 2

The electromagnetic field in nuclear Fermi gas and nuclei has been studied. Because in the nuclear Fermi gas the expectation value of the electric charge density operator is not zero, different from that in vacuum, the U (1) local gauge symmetry of electric charge is spontaneously broken in the nuclear Fermi gas, and consequently, the photon gains an effective mass. Perturbation calculation of the photon self energy shows that the effective mass of photon is about 5 42MeV in the symmetric nuclear Fermi gas at the saturation density ρ 0=0.16fm -3 and about 2.0MeV at the surface of 238 U. Furthermore , it is concluded that it is just the two body decay of a massive photon that causes the discovery of sharp lines of electron positron pairs in low energy 238 U+ 232 Th heavy ion collisions experiments.