STUDY OF THE POSSIBILITY OF SUPERNARROW DIBARYON PRODUCTION IN THE ~γd → π + D REACTIONS

The possibility of observation of supernarrow dibaryons, decay of which into two nucleons forbidden by the Pauli principle, produced in processes of charged pion photoproduction by polarized photons from the deuteron is analyzed. It is shown that the expectable dibaryon yield may exceed the background by a factor of 10–100. The possibility of existence of multi-quark states is predicted by QCD [1]. This is a new type of matter. The experimental discovery of such states might have serious consequences for both elementary particle physics and nuclear physics. A search for narrow 6-quark states (dibaryons) is being carried out for a long time (see, e.g., [2, 3]), and a number of candidates for these states has been found. However, up to the present day, one can hardly unambiguously state that the features found in these experiments were indeed dibaryons. This associated, first of all, with a relatively low contribution of dibaryons to the processes under study and the uncertainty of the contribution of the background processes. We propose to seek for supernarrow dibaryons whose decay into two nucleons is forbidden by the Pauli principle [4, 5, 6, 7, 8, 9]. Such dibaryons satisfy the condition (−1)P = +1, (1) where T is the isotopic spin, S is the internal spin, and P is the parity of the dibaryon. These dibaryons with mass M < 2mN + μ (mN is the nucleon mass and μ is the pion mass) can mainly decay into two nucleons with photon emission. The contributions of such dibaryons to processes of strong interactions of hadrons are very low. However, their contributions to processes of electromagnetic interactions on light nuclei may be several orders of magnitude higher than the values of cross sections of these processes out of the resonance [4, 5, 7]. In the present paper we study the possibility of observation of supernarrow dibaryonsD(T = 1, J = 1, S = 1) and D(T = 1, J = 1, 0) having the mass M < 2mN + μ and satisfying the condition (1) in the processes of π meson photoproduction by polarized photons from the deuteron ~γ + d → π +D,D → γNN. (2) The dibaryons under consideration have very small decay widths. Their values, calculated under assumption that γNN decay of the dibaryons goes on mainly through the singlet virtual S0 level in the intermediate state, are presented in Table 1 [7].