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First Creation of Anti-Strange Hypernuclei
runagate writes "Brookhaven National Laboratory has created a heretofore unknown form of matter. The matter we normally encounter, and are composed of, has nuclei of protons and neutrons that contain no strange quarks. It was known that anti-strange matter could exist, and using the Solenoidal Tracker at Brookhaven's RHIC, scientists detected a couple of dozen instances of antihypernuclei. The 'Z' axis of the Periodic Table has already been extended in the positive direction by the discovery of hypernuclei, but this new discovery extends it in the negative direction for this new type of 'strange' antimatter — which may exist in the core of collapsed stars and may provide insight into why our universe appears to be made almost solely of matter and not antimatter." The Register's coverage reproduces a helpful diagram.
No.
Strange quarks behave just like down quarks (which are one of the two constituents of protons and neutrons). The only difference is that they have a higher mass.
Y'know how heavy water is just like light water, except one of the hydrogens is replaced with a deuterium atom? This stuff is similar, except one of the down quarks is swapped with a strange.
Unlike deuterium, though, these lambda baryons are unstable, because the strange quark is unstable. They can decay by the weak interaction (the same thing responsible for beta decay) into an up quark and a couple of leptons (electrons and neutrinos). The amount of time that weak decays take is very long compared to the time-scales involved in quark physics, but it's still very short compared to a second.
Hypernuclei with negative strangeness haven't been "created for the first time". They've been produced in RHIC collisions for as long as they've been running (with sufficient energy), and it's only now that we've been able to see them.
That, however, is quite the accomplishment, as relativistic heavy ions collisions are so complex that we're hardly begun to understand what happens in them. Think a two-hundred-truck collision at 1,000 mph, and you're interested in what screw came from which truck and how the drivers' shoes were tied.
[No truck drivers were hurt in the writing of this comment!]
I'm not a physicist, but what I got from the article (+ some background for those who have forgotten/never took nuclear physics:)
* Atoms are made up of protons, neutrons, and electrons. Atomic nuclei contain just protons and neutrons.
* Protons and neutrons themselves are made up of smaller particles called quarks.
* In regular matter the protons and neutrons are made up of two different types of quarks, called up and down quarks.
* Two up quarks + one down make up a proton, one up + two down give you a neutron.
* If you replace some or all of the up or down quarks with a different type of quark (up -> strange, down -> charm I believe) then you get a new type of subatomic particle. If you think of the periodic table as being a building, the regular periodic table makes up the ground floor, while atoms using these strange/charm subatomic particles would live on higher floors.
* If you replace all the up and down quarks with antiup and antidown quarks, you get a new type of subatomic particle (the antiproton or antineutron.) They live in the other wing of the periodic building.
* This article reports that researchers have found particles where both the quarks have been replaced by antiquarks and some or all of those antiup/antidown quarks have been replaced by an antistrange quark. These are in the basement of the periodic building, the first particles discovered there.