The pentaquark is not just any new particle... It represents a way to aggregate quarks, namely the fundamental constituents of ordinary protons and neutrons, in a pattern that has never been observed before in over fifty years of experimental searches. Studying its properties may allow us to understand better how ordinary matter, the protons and neutrons from which we’re all made, is constituted.
Thanks, that quote is making it a little clearer. I'll try to simplify even more:
When a particle consists of quarks (not all particles do; e.g. an electron is not made of quarks), "the numbers" need to "add up".
"The numbers" are the so-called "color charge". No relation to real colors, it's just a name :). The color of a quark can be red, green or blue. In total, baryons (big fat particles, e.g. protons and neutrons) have to be white.
Example: Proton: Blue up-quark, Red up-quark, Green down-quark. R+G+B = white.
As you can see, there can't be a baryon with 4 quarks -- it would be RRGB or RGGB or RGBB or RRRG...; definitely not the same amount of red, green and blue.
But 5 quarks are possible again, because there are anti-quarks, which also have an anti-color; you have 3 quarks that are R+G+B, and then e.g. another Red one, and an Anti-Red. The Anti-Red cancels out 1 Red, so color-wise you again have RGB=white.
And now the LHC has shown that those theoretical 5-quark-particles ("pentaquarks") actually exist. That's quite impressive.
From the LHCb spokesperson, Guy Wilkinson:
Thanks, that quote is making it a little clearer. I'll try to simplify even more:
When a particle consists of quarks (not all particles do; e.g. an electron is not made of quarks), "the numbers" need to "add up".
"The numbers" are the so-called "color charge". No relation to real colors, it's just a name :). The color of a quark can be red, green or blue. In total, baryons (big fat particles, e.g. protons and neutrons) have to be white.
Example: Proton: Blue up-quark, Red up-quark, Green down-quark. R+G+B = white.
As you can see, there can't be a baryon with 4 quarks -- it would be RRGB or RGGB or RGBB or RRRG...; definitely not the same amount of red, green and blue.
But 5 quarks are possible again, because there are anti-quarks, which also have an anti-color; you have 3 quarks that are R+G+B, and then e.g. another Red one, and an Anti-Red. The Anti-Red cancels out 1 Red, so color-wise you again have RGB=white.
And now the LHC has shown that those theoretical 5-quark-particles ("pentaquarks") actually exist. That's quite impressive.
So... can you simplify the charm quark and anti-charm quark? Because that sounds adorable.
It does :) While other particles have greek(-ish) names, it looks like scientists decided to have some fun with quarks:
They come in 6 flavors: up, down, strange, charm, bottom and top. And they have a color charge: red, green or blue.