How can i get data by using "escape string tag"

[CHN-STUDENT]

from(bucket: "hg-nhdb")
  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
  |> filter(fn: (r) => r["_measurement"] == "alarm_points")
  |> filter(fn: (r) => r["_field"] == "real_value")
  |> filter(fn: (r) => r["tagname"] == "\\HG\\XXXX\\FM_FIQ_E100A1_DACA_PV")
  |> aggregateWindow(every: v.windowPeriod, fn: mean, createEmpty: false)
  |> yield(name: "mean")

my tagname is \HG\XXXX\FM_FIQ_E100A1_DACA_PV, but i get error

 compilation failed: error @25:87-25:114: expected comma in property list, got DOT error @25:105-25:113: unexpected token for property key: DOT (.) error @27:39-27:66: expected comma in property list, got DOT error @27:57-27:65: unexpected token for property key: DOT (.) error @27:95-27:122: expected comma in property list, got DOT error @27:113-27:121: unexpected token for property key: DOT (.) error @28:36-28:63: expected comma in property list, got DOT error @28:36-28:42: invalid expression @28:35-28:36: : error @28:54-28:62: unexpected token for property key: DOT (.) error @28:100-28:127: expected comma in property list, got DOT error @28:118-28:126: unexpected token for property key: DOT (.)

also use \ or \\ or \\\\, but still can not work,could someone help me?