Search for the light hadron decay χc1 (3872) →π+π-η

With a data sample corresponding to an integrated luminosity of 11.5 fb-1 collected with the BESIII detector operating at the BEPCII storage ring, for the first time the light hadron decay χc1(3872)→π+π-η is searched for. While no significant signal is observed, the upper limits at the 90% confidence level for σ[e+e-→γχc1(3872)]B[χc1(3872)→π+π-η] at center of mass energies from 4.13 GeV to 4.34 GeV are determined. By normalizing to the χc1(3872)→π+π-J/ψ decay channel, a 90% confidence level upper limit for the branching fraction ratio R=B[χc1(3872)→π+π-η]/B[χc1(3872)→π+π-J/ψ]<0.12 is given. These measurements provide important inputs for understanding the internal structure of the χc1(3872) resonance. © 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.