Fawk, im never going to memorise the particle zoo!
You don't have to!
That would be like memorizing all of the elements; it's better to just understand what makes them up.
Baryons like these Xi's are just groups of three quarks. If there are only two quarks, they are called Mesons. These are composite particles, and their properties are basically just the sum of the quarks that make them up.
There are also Leptons (for example electrons and neutrinos). Quarks and leptons have "spin" in increments of 1/2, 3/2, etc. Collectively they are called Fermions.
There are other particles that have "spin" in increments of 1, 2, etc. Due to [math], this allows them to behave differently, and transmit force between particles. These are called Bosons, and include things like the photon and the Higgs.
It takes energy to be massive, so things that are heavy tend to decay into lighter particles. This is for the same reason that balls roll down hills; lower energy state. Particles can only decay in in ways that don't change some of their values--for example the total electrical charge of the system can't be different after it decays.
So this new particle they're talking about is made of an Up, a Strange, and a Bottom. Ok, so its total electric charge is 2/3 + -1/3 + -1/3 = 0; it's electrically neutral. Memorize shmemorize!
Obviously there are interesting subtleties (for example, those mesons I mentioned earlier can also transmit force
), but the basics aren't too
bad to wrap your mind around.http://en.wikipedia.org/wiki/Standard_model