Blog – Of Particular Significance

CBS NEWS, today: “A never-before-seen subatomic particle has popped into existence inside the world’s largest atom smasher, bringing physicists a step closer to unraveling the mystery of how matter is put together in the universe.”

Overall, this is not a bad article — but that last bit is propaganda.  Maybe physicists made a nano-step (“nano” = one billionth).  We knew this particle — a composite object made from known particles — would be there; we just didn’t know its details.  To suggest this is a step toward a breakthrough is just silliness.  Of course all new information proves useful eventually for something, but… really!

And the first part?  Less exciting than it sounds (though a very nice bit of research!)  Here’s the link to my post about this from Friday, explaining that the CMS experiment at the Large Hadron Collider has reported very strong evidence for a new composite object — a hadron, a member of a particular subclass called a `baryon’ —  made from a single bottom (or `beauty’ — or just `b’) quark and from other known particles.

The reporter tells the usual white lie:

Baryons are particles made of three quarks (the building blocks of the protons and neutrons that populate the nuclei of atoms). Beauty baryons are baryons that contain at least one beauty quark (also known as a bottom quark). The new specimen is a particular type of excited beauty baryon called Xi(b)*, pronounced “csai-bee-star.”

A better description of baryons (including protons) is that they are made from three quarks, many gluons, and many additional pairs of quarks and anti-quarks.  The three excess quarks are the ones being referred to in the above paragraph.  See my article on what protons are and Friday’s post on this new one, which shows a sketch that gives better intuition about what protons and Xi(b)*s look like.

[Sometimes white lies get you into a lot of trouble later.  The fact that protons have gluons and anti-quarks in them is crucial to understanding how the Large Hadron Collider does its thing.]

The reporter gets this part right:

The Xi(b)* particle had been predicted by a physics theory called quantum chromodynamics, which predicts how quarks bind together to form heavy particles, but had never before been observed.

“It was expected to be more or less where it was found,” [Vincenzo] Chiochia said. “Not all of those heavy states have been discovered, so you have to look for all those particles. It may well be that the theory is not complete. In this particular case it was expected, but we have to keep looking for things that are unexpected.”

Well.  I don’t know about that, Dr. Chiochia.  As a quantum field theorist, I would agree that “quantum chromodynamics” (which does more than what the reporter writes — it is the set of equations that describes and predicts all of the interactions of quarks, gluons and anti-quarks of all types) might indeed be turn out to be incomplete.  But if you really want to look for places where it might fail, this is an especially bad place to look!  This composite particle itself may be new, but the forces and particles required to make this object have already been very well-studied in other contexts.  (Nevertheless, congratulations on nice work!)

Oh, and by the way, Wind Farms Do Not Cause Global Warming.  They may cause some local mixing of warmer air just above the ground at night down to the surface near the wind farm itself; this does not increase the overall temperature of the planet.  Read headlines (and articles) very carefully.  http://www.washingtonpost.com/blogs/ezra-klein/post/no-wind-farms-are-not-causing-global-warming/2012/04/30/gIQAMl2GsT_blog.html