Study of e^+e^- X (3872) and X (3872) from 4. 66 to 4. 95 GeV

Using data samples with an integrated luminosity of 4. 5~fb^-1 collected by the BESIII detector at center-of-mass energies ranging from 4. 66 to 4. 95 GeV, we study the processes of e^+e^- X (3872) and e^+e^- X (3872). With the e^+e^- X (3872) process, the branching fraction ratio RB (X (3872) J/) B (X (3872) ^+^- J/) is measured to be 0. 380. 20ₛtat. 0. 01ₛyst. (R< 0. 83 at 90\% confidence level). In addition, we measure the ratio of the average cross section of e^+e^- X (3872) to e^+e^- ₂₁ (₂₂) to be ₗ (₃₈₇₂) /_₂₁~ (ₗ (₃₈₇₂) /_₂₂) =5. 21. 0ₛtat. 1. 9ₛyst. ~ (5. 51. 1ₛtat. 2. 4ₛyst. ). Finally, we search for the process of e^+e^- X (3872), and no obvious signal is observed. The upper limit on the ratio of the average cross section of e^+e^- X (3872) to e^+e^- X (3872) is set as ₗ (₃₈₇₂) / ₗ (₃₈₇₂) <0. 23 at 90\% confidence level.