CAN ONLY FLAVOR-NONSINGLET H-DIBARYONS BE STABLE AGAINST STRONG DECAYS

Using the QCD sum-rule approach, we show that the flavor-nonsinglet H dibaryon states with J(pi)=1(+), J(pi)=0(+), I=1 (27 plet) are nearly degenerate with the J(pi)=0(+), I=0 singlet H-0 dibaryon, which has be en predicted to be stable against strong decay, but has not been obser ved. Our calculation, which does not require an instanton correction, suggests that the H-0 is slightly heavier than these flavor-nonsinglet H's over a wide range of the parameter space. If the singlet H-0 mass lies above the Lambda Lambda threshold (2231 MeV), then the strong in teraction breakup to Lambda Lambda would produce a very broad resonanc e in the Lambda Lambda invariant mass spectrum which would be very dif ficult to observe. On the other hand, if these flavor-nonsinglet J=0 a nd 1 H dibaryons are also above the Lambda Lambda threshold, but below the Xi(0)n breakup threshold (2254 MeV), then because the direct, str ong interaction decay to the Lambda Lambda channel is forbidden, these flavor-nonsinglet states might be more amenable to experimental obser vation. The present results allow a possible reconciliation between th e reported observation of Lambda Lambda hypernuclei, which argue again st a stable H-0, and the possible existence of H dibaryons in general.