Evolutionary tracks of LMXBs in the ﹩{M}_{2}-{P}_{{\rm{orb}}}﹩ plane. From left to right the initial masses of the companion stars are taken to be ﹩{M}_{2,{\rm{i}}}=1.0,1.5,\mathrm{and}\;2.0\;{M}_{\odot },﹩ respectively. The green solid, red dotted, and black dotted lines represent the mass transfer processes with a stable and unstable accretion disk and the stage of RL detachment, respectively. The dot–dashed line shows the theoretical ﹩{P}_{{\rm{orb}}}-{M}_{{\rm{WD}}}﹩ relation for Case B mass transfer. The asterisks on the evolutionary tracks indicate the time when the NS has accreted ﹩0.1\;{M}_{\odot }﹩ material. The two brown dashed lines give the orbital periods with a ZAMS and TAMS donor. Also plotted are redbacks in the Galactic disk and globular clusters (blue symbols).