1. Search for supernarrow dibaryons in the reaction g + 3He  N + gNN L.V. Fil’kov
6-quark state
nucleon
(dibaryon)
D N N G~ MeV
6-quark states, decay of which into two nucleons is forbidden by
Pauli exclusion principle.
M < 2mN + mp D → g + NN
g + d
* Wide dibaryons : G~ MeV
* Narrow dibaryons : G~ MeV
* Supernarrow dibaryons : G<< 1 keV
G  eV
(-1)T+S P = +1

2. g 31S0 if T = 1 D(T=0, JP=0+ ), D(0, 0─), D(T=1, J =1+), D(1,1─) N D
X = {
d if T = 0
31S0 if T = 1 X N
M(GeV)
1.90
1.91
1.93
1.96
1.98
2.00
G(1,1+) (eV)
0.51
1.57
6.7
25.6 48 81
G(1,1─) (eV)
0.13
0.39
1.67
6.4 12 20

3. A construction of an adequate QCD model.
2. Astrophysics: an evolution of compact stars.
3. Quark-gluon plasma: specific signals of a production
of QGP with the big baryon dencity.
4. Nuclear physics: a formation of dibaryon-nuclei;
a region of stability of neutron-rich nuclei.

4. MIT bag model: D(T=0; JP = 0─, 1─, 2─; M=2110 MeV),
1. P.J.G. Mulders et al. (1980)
MIT bag model: D(T=0; JP = 0─, 1─, 2─; M=2110 MeV),
D(1; 1─; M=2200 MeV)
M > 2mN + mp D  p NN
2. V.B. Kopeliovich (1993)
Chiral soliton model: D(T=1; JP = 1+; M ≃1940 MeV),
D(0; 2+; M ≃1990 MeV)
3. T. Krupnovniskas et al. (2001)
Canonically quantized biskyrmion model:
M < 2mN + mp
one dibaryon with J=T=0,
two dibaryons with J=T=1

5. p + d  p + X  p + p X1 X1= g + n MpX1: 1904±2, 1926±2, 1942±2
L.V. Fil’kov, V.L. Kashevarov, E.S. Konobeevski et al., Phys.Rev. C61, (2000); Eur.Phys.J. A12, 369 (2001)
Proton Linear Accelerator of INR (Moscow).
MpX1: 1904±2, 1926±2, 1942±2
SD:
G < 5 MeV (experimental resolutions)
if X1 = n → MX1 = mn
if X1 = g + n → MX1  mn
Simulation of mass MX1 spectra gave:
MX1 = 965, , MeV
Experiment:
MX1= 965±2, 986±2, ±2
X1= g + n

6. Research Center for Nuclear Physics (Japan)
p d  p pX p d  p dX1
Research Center for Nuclear Physics (Japan)
H. Kuboki et al. Phys. Rev. C 74, (2006)
1. No resonance structure in the missing mass spectra
of pX and dX1 was observed.
2. No resonance structure in missing mass spectra of X.
(It is at variance also with the results of the work of
B. Tatischeff et al. (Phys. Rev. Lett. 79, 601 (1997))
INR: beam intensity nA
RCNP: beam intensity (15 – 20) nA

7. g + 3He  p + D 3He  (d + p) + (31S0 + N) h 10-2 D  g NN D  g d
All particles in the final sate should be detected

10. Background: g + 3He  0 + N + NN g + 3He  0 + p + d
Efficiency of p0 detection in Crystal Ball  90%.
2. The background gives main contribution in the region of invariant
mass M > 2mN + mp .
3. 90% of a proton-spectators have low energy and are undetectable.
4. Kinematics cuts:
a) Nucleons from the decay of SND have to be emitted into
a narrow angle cone.
b) Narrow distribution of DENN.
… ets.

11. Conclusion Experimental discovery of SND would have important
consequences for particle and nuclear physics and astrophysics.
Three candidates for SNDs have been observed in INR. However, in
order to argue more convincingly that the states found are really SNDs,
an additional experimental investigation of such states production is
needed.
The new experiment to search for SND at MAMI-C in the reactions
g + 3He  N + gNN and g + 3He  p + gd is proposed.

12.  d0 +  pn MAMI (Preliminary)
MM(,0) – md (MeV)

13. JLAB