| Quantum Chromodynamics(QCD) is the elementary theory of the strong interactions. It is of great importance to test and develop QCD theory for understanding the nature of strong interactions. So far, all established hadrons consist of two or three quarks, however, QCD theory allows the existence of new forms of hadrons(glueballs, hybrids and multi-quark states), but none of them has been establishedexperimentally yet. So it is very important to search for the multi-quark states, hybrids and glueballs in experiments for testing and developing QCD and resonance theory, which is one of the most important physics goals for many high energy physics experiments in the world.J/ψdecays provide an excellent laboratory for hunting new forms of hadrons. The enhancement X(1860) in J/ψ→γp(?) has stimulated a number of theoretical interpretations. The pure final states interaction(FSI) with isospin I=1 is one of the interpretations to X(1860). However, theoretically, isospin I=1 is suppressed in J/ψradiative decays.Based on 58 million J/ψevents collected with BESII detector, The decays J/ψ→γa2 and J/ψ→γπ(1800) are studied to investigateof isospin I=1 suppression in the J/ψradiative decays, which will be helpful in understanding the nature of the observed X(1860) and in clarifying the role of p(?) FSI effects.we report the analyses of J/ψ→γa2 (1320) and J/ψ→γπ(1800). No obvious enhancement near the 1.3GeV/c2 and the 1.8GeV/c2 regionsin theπ+π-π0 invariant-mass spectrum. The upper limits of the branching ratios are determined to be:B(J/ψ)→γa2(1320)) < 1.1×10-4 (90% C.L.)B(J/ψ→γπ(1800))·B(π(1800)→π+π-π0) < 6.0×10-5 (90%C.L.)Compared to the branching ratios of the corresponding SU(3) singlet f2(1270) andη(1760) , which branching ratios are B(J/ψ→γf2(1270)) = 1.38×10-3 and B(J/ψ→γη(1760)) = 1.98×10-3 respectively,the decay J/ψ→γXI=1 is more than an order magnitude weaker than J/ψ→γXI=0.J/ψ→γXI=1 decay mode is suppressed, and the FSI with I=1 interpretation of the p(?) enhancement in J/ψ→γp(?) is disfavored. |
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