Friday, November 03, 2006

50 Years Particle Data Group

Yesterday, I sorted through my mailbox at the institute, which revealed (besides several past due bills for my BlackBerry) an envelope from the Particle Data Group (PDG) with the new edition of the Particle Data Booklet. The booklet, which comes in a different color every year, is probably the most reliable companion of my postdoc life.

Besides all the known details about the elementary particles, and constraints on parameters in different models, it lists all these constants that theoretical physicists like to set equal to one, and things like the distance to the sun or the baryon density of the universe. But maybe most importantly, it contains the definitions of kinematical quantities (pseudo-rapidity, anybody?) and how to transform these from the lab frame in the center of mass frame and stuff like that. Besides this, it gives you the absolutely minimal introduction into the standard model.

I was kind of disappointed though because I also expected the complete review, and the 'particle physicist's pocket diary'. I usually put the booklet in the glove box of my car, and the review on my desk. The pocket diary has a good listing of physics institutes in the US, which is pretty handy for applications. But the only other thing the envelope contained was a brochure.

At first sight I thought it's one of these advertisements for vacuum pumps or likewise, but it turned out to be in honor of the 50th anniversary of the PDG. It has a lot of photos of the members of the group, and briefly tells the group's history. Apparently, earlier versions of the booklet had a ruler in inch and centimeter printed on it. The most amusing thing is what's written in the front flap:

    A [...] problem occurred in the 1994 Booklet, so PDG thought it necessary to provide their readers with explanations as noted below.

    The 'centimeters' on the ruler on p. 227 of the Booklet are 0.97 inches long, because:

      a) the booklets were returned from the printer at 0.25 times the speed of light;

      b) A theorist is in charge of the Particle Data Group;

      c) The PDG feels it has the right to redefine anything it wants;

      d) There is a general decline of standards;

      e) There was an international conspiracy;

      f) It was a congressionally-mandated cost-saving measure;

      g) PDG gives you more cm/inch than anyone else.

In case you haven't yet noticed it, the PDG has now a website called PDGlive, which doesn't only list all the data, but has direct links to the references on SPIRES.

See also: PDG 50th anniversary festivities.

A nice weekend to all of you :-)



  1. Shouldn't we have a theoretical particle data book as well, with all the postulated particles and their properties?

  2. h) the ruler was calibrated in chemical units.
    i) heteroskedasticity, diversity employee, faith-based initiative.
    j) evidence for inconstant Fine Structure Constant.
    k) Allais effect during compositing.
    l) ANOVA!

    (BTW, it's 0.24c not 0.25c)

  3. Hi Arun,

    you should have a look at the PDB. It lists all the postulated particles, their properties, and the current constraints. E.g. axions, kk-excitations (extra dimensions), sterile neutrinos, magnetic monopoles, supersymmetry, technicolor, etc. If your fancy theory gets serious enough to be included in the PDB search, you've kind of made it ;-)



  4. I found another anomaly with the 1957 PDG "wallet card". The "8-cm" long ruler is actually 8.1(+/-0.5) cm in length, measured with 3 different rulers. Funny!


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