The Hunt for The Wily Strange/Heavy Baryon
Scientists have for the first time presented indirect evidence for the existence of the elusive heavy strange baryon.
This isn’t a weird corpulent variant of bigfoot. Baryons are a special class of subatomic particle. Look around you…everything you see is made of baryons. Indeed, almost everything in the visible universe is made of them. The most recognizable types of baryons (in terms of name/brand recognition) are the protons and neutrons at the core of atoms. What makes them baryons is the fact that they are each made of 3 fundamental and elementary components of matter… quarks. There are 6 kinds of quarks but protons and neutrons have to be a specific combination of just the Up and Down ones.
So what about this heavy strange baryon thingie? This baryon (a family of particles actually) is different in that it doesn’t stick around for long, it’s very massive, and it’s made up of at least one other type of quark called Strange. Our standard model of physics predicts its existence but its devilishly difficult to find so we may have to be satisfied with just indirect evidence that it exists.
This is accomplished by producing what’s called a quark-gluon plasma one of my favorite types of matter. Yes, this is a bona-fide state of matter beyond the boring old solid, liquid, gas (and many others).
This phase of matter is what the entire universe primarily consisted of for a brief period of time after the big bang. Temperatures and densities were so high that the quarks were allowed to roam free, not bound to each other as they are in the much chillier temperatures found everywhere in the universe now (including inside stars). This is actually quite extraordinary because normally you can’t pull apart bound quarks easily. They exhibit a property called Confinement. Their connection does not weaken as you pull them apart as you might suspect, it gets stronger, kinda like a rubber band. If you pump enough energy into them, instead of breaking free, the quarks say “Oh Yeah?” and the energy you’ve been throwing at them goes instead into the creation of a whole new bound set of quarks. It takes an extraordinary amount of energy therefore to invoke another quark property called Asymptotic Freedom which means that very high-energy reactions cause quarks to interact only very weakly creating…you guessed it…a quark gluon plasma. As the name implies, this special plasma isn’t just made of quarks. It’s suffused with gluons as well. These are force carriers. They mediate the most powerful force in nature, the strong force, which acts between quarks. In this sense they are roughly comparable to photons which mediate the electromagnetic force.
Where was I…oh yes, quark-gluon plasma. Only two labs in the world currently have the ability to investigate this primordial soup of elements. The Relativistic Heavy Ion Collider (RHIC) is one of them and it is this facility that claims indirect evidence for the heavy strange baryon. Using supercomputers, they were able to investigate the results of countless high-energy particle collisions that created the soup. In it they found direct evidence, not for the heavy strange baryon, but other less massive yet still strange ones like the Omega and Lambda baryons. These oddballs popped out of the plasma at temperatures lower than they should have been able to. It turns out that that theory predicts this would happen only if the heavy strange baryon was there to make it happen.
Regarding this, Brookhaven theoretical physicist Swagato Mukherjee said the following:
“It’s similar to the way table salt lowers the freezing point of liquid water…(the heavy strange baryons) are like salt molecules floating around in the hot gas of hadrons, making other particles freeze out at a lower temperature than they would if the ‘salt’ wasn’t there.”
This research is fascinating for me not just because it provides compelling evidence for the latest denizen of the universe’s particle zoo. It can actually help us learn more about why and how matter came to be in the universe, forming bound states of quarks without which they beauty of the universe and life of any kind might not exist.
Plus I just wanted to talk about quark-gluon plasmas
Image Credit: RHIC