Search for neutral strange quark matter in high energy heavy ion collisions

We present results of a search for neutral strange quark matter (strangelets) in $11.6A\mathrm{GeV}/c\mathrm{A}\mathrm{u}+\mathrm{P}\mathrm{b}$ reactions from the 1995 run of experiment E864 at the Brookhaven Alternating Gradient Synchrotron. We have sampled approximately 1.3 billion 10% most central $\mathrm{A}\mathrm{u}+\mathrm{P}\mathrm{b}$ interactions and have observed no statistically significant signal for neutral strangelet states with baryon number in the range $6<A<\mathrm{}100.\mathrm{}$ We set upper limits on the production of these exotic states at the level of $8\times {10}^{-8}$ per central collision for mass $>20\mathrm{}\mathrm{GeV}{/c}^2.$ These limits are the first limits reported on the production of heavy neutral strangelets. They complement searches for positively and negatively charged strangelets also conducted by our collaboration. We discuss the implications of these results on strangelet production mechanisms and the stability of strange quark matter.