Investigating the η1′(1855) exotic state in the J/ψ→η1′(1855)η(′) decays

An analysis of the J/ψ→ηη′γ decay by the BESIII collaboration claims the observation of an exotic state η1(1855) with IGJPC=0+1−+. To establish its C-parity partner η1′(1855) in the picture of the KK¯1(1400) molecular state, we propose that J/ψ→η1′(1855)η(′) receives the main contributions from the final state interaction of KK⁎(K+K⁎−, K−K⁎+, K0K¯⁎0, and K¯0K⁎0). Specifically, K and K⁎ in J/ψ→KK⁎ decays transform as η1′(1855)η(′), by exchanging a K1(1400). We predict B(J/ψ→η1′(1855)η)=(6.3−3.5+12.6)×10−6, and B(J/ψ→η1′(1855)η′)=(6.5−4.6+6.6)×10−6, which can be studied in the J/ψ→K⁎K¯⁎η(′) decays.