I just got back from a four day American Physical Society meeting in Anaheim. It was also a Division of Particle and Fields meeting, my old vocation. So I am going to milk it for a few blog entries. This one is on the very exciting work of Stan Brodsky and colleagues at the Stanford Linear Accelerator Center on the fundamental discrepancies between our understanding of field theory and the calculation of the cosmological constant Lambda. Lambda is the constant in Einstein’s general relativity equation that is responsible for the Dark Energy that is causing the expansion of the universe to accelerate.
Calculating the energy of the vacuum fluctuations in QCD, the theory of the strong interactions, using the quark-antiquark vacuum condensate that is supposed to exist everywhere, gives a value of 10^45 times bigger than the observed Lambda. Brodsky and colleagues argue that such a condensate does not exist when you look at a simple light cone frame way to calculate the vacuum diagrams, and that they in fact give zero to Lambda.
He also argues that the zero point energy in the standard model Higgs theory of unified weak and electromagnetic interactions comes from the vacuum expectation of the Higgs being present everywhere. If the Higgs is really a bound state of technicolor constituents as in a model with another strong color interaction of very heavy technicolor quarks, then again the Higgs vacuum does not fill all space, and the vacuum energy of that is zero, instead of 10^56 times the observed Lambda.
I didn’t get his solution to a quantum gravity theory with Lambda equal to the fourth power of the Planck mass, giving the 10^120 times the observed Lambda, but we don’t yet have a definitive theory of that. He speculated that the actual observed Lambda may have its origin in gravitational interactions.
