Stability of strange matter

General Questions
#1

You may have seen the recent articles about possible new evidence for strange matter stars. These stars would be similar to neutron stars except they are made of matter with 1 up quark, 1 down quark, and 1 strange quark. From my reading on the subject it seems that the huge pressure in a strange star is what keeps the strange matter stable. It is my understanding that small amounts of strange matter are not stable and decay in a small fraction of a second.

My first question is whether my understanding is correct so far.

Yesterday in the Dallas Morning News there was a story about two Southern Methodist University scientists who have examined seismic records and claim to have found evidence that two strange quark matter nuggets zipped through the earth in the fall of 1993. These nuggets were perhaps a millimeter across but weighed about a ton and would not have interacted with normal matter. The article states that strange quark matter is the most stable form of matter in the universe.

As I type this, I think I may have figured out the answer. Maybe.

A strange particle (the u/d/s kind) is the another name for a lambda particle, right? Lambda particles decay very quickly (I think).

Is the answer to my confusion that strange matter refers to atoms of multiple strange particles and that is the form of matter that is stable?

If that is correct, how many strange particles would exist in stable strange matter?

#2

Your understanding of the star is correct: There is no experimental reason to believe that strange matter is stable under any less extreme conditions, and the only experimental evidence that it would be stable in a strange star, is the (putative) observation of such stars. There’s a wealth of theoretical results here, but they don’t always agree, and in the end, experiment is the final arbiter.

On your second question, a quark nugget is a hypothetical “subatomic” particle consisting of a great number of quarks, not necessarily neatly divided into individual baryons. In other words, if you take 210[sup]29[/sup] up quarks, 210[sup]29[/sup] down quarks, and 210[sup]29[/sup] strange quarks, you could assemble them into 210[sup]29[/sup] unstable [symbol]L[/symbol] particles, or you might be able to assemble them into a single, possibly stable, quark nugget, weighing a ton. If such a thing were uncharged, it would not interact very strongly with normal matter, but there would be at least some interaction (otherwise they wouldn’t see any evidence in the seismic record). Of course, I would not consider a popular newspaper report of one unreplicated result to be evidence of an actual detection, and most likely the scientists were much more conservative in the claims in the original journal paper (something like “The results we observed appear to be consistent with an interaction with a 10[sup]6[/sup] gram weakly-interacting particle (such as a strange quark nugget) passing through the Earth, but further measurements and observations would be needed to rule out other possibilities”).

#3

Thanks very much for your reply. I assume that the seismic record was based on gravitational effects which could occur absent any actual matter interaction. The work has been submitted to a peer-reviewed scientific journal, but the article doesn’t say which one.

#4

I’m about to display my collossal ignorance of physics here, but if a 1-ton, weakly interacting object passed through me, would I notice?

#5

Rysdad, my understanding is that you would not notice that little 1 ton object passing thorough you.

Chronos, upon rereading your reply I’m still confused. You said that a “quark nugget” is a sub-atomic particle. But a Lambda particle is a baryon and I thought that since the proton is the only stable baryon, the only way that strange matter (in isolation) would be stable is if it was confined in a larger “atom” containing multiple strange particles. I have seen reference to doubly strange nuclei. Wouldn’t something like that be necessary for stability rather that just a big conglomeration of strange particles?