Higgs and the Amazing Technicolor Dreamcoat

Recently, I watched the documentary Particle Fever at Cine, a local theater here in Athens, GA. (The film is streaming on Netflix also.) It was a great look into the hoard of people at CERN that got the Large Hadron Collider running. It also highlighted the discovery of the Higgs boson, the elementary particle in the Standard Model that gives everything mass. Before the discovery of the Higgs, there were two competing theories: the Standard Model and the Multiverse. The Standard Model expected the Higgs boson to have an energy of about 115 GeV, while the Multiverse theory expected the Higgs boson to have an energy around 140 GeV. The LHC detected a signal at around 125 GeV, right smack dab in the middle. For reasons I don’t understand, the Standard Model won the battle, though many prominent scientists (Brian Greene, Stephen Hawking, Michio Kaku, NdGT, to name a few recognizable names) have supported the hypothesis and cashmoney prizes have been given to purveyors of the Multiverse theory (Alan Guth, Andrei Linde, and Alexei Starobinsky).


A simulated Higgs boson signal made by the collision of two proton beams.

Either way—whether you support the Standard Model or the Multiverse—everyone’s happy that the Higgs boson was found. That is, everyone except a team of researchers from the University of Southern Denmark. They’ve come to rain on the parade. In a new paper in Physics Review D, beautifully named “Technicolor Higgs boson in the light of LHC data”, they claim that the signal at 125 GeV could instead be the TC Higgs, the weird cousin of Higgs that was named after his uncle but everyone kind of forgets is there until Christmas when they’re reminded of his tie-dye shirts, sock-filled sandals, and suspiciously bloodshot eyes. The TC Higgs (TC = technicolor) belongs to a model one step past the Standard Model that is actually much less interesting (to us non particle physicists) then the name would lead one to believe. It has something to do with electroweak gauge symmetry breaking and how that makes mass.

“The current data is not precise enough to determine exactly what the particle is. It could be a number of other known particles,” Mads Toudal Frandsen, the PI of the work, said in a press release.

This new analysis doesn’t debunk the Higgs finding, it just politely states that maybe the evidence isn’t as strong as we might think. The 125 GeV signal fits other theories, so maybe we shouldn’t be so quick to jump on the Higgs train. Frandsen hopes more data from the LHC will help distinguish between the Higgs and TC Higgs. The LHC is set to resume research in early 2015, so we’ll have to be on the lookout for new happenings there. Whatever the LHC discovers, Peter Higgs and Francois Englert will be secure in the knowledge that their Nobel Prize comes with a no-takebacksies clause.

Simplify the Universe

Particle interactions calculated with a single term all done by hand?! That’s crazy. In case you have nothing to base calculating particle interactions in quantum field theory on, just imagine having thousands of puzzle pieces scattered everywhere to suddenly, without all the pesky pieces, having a single, unified picture. All it takes is some new thinking and a little geometry.

In this new model, physicists describe the universe by an amplituhedron, an infinite-dimensional geometric object. The volume of this object is equal to the scattering amplitude—the holy grail of particle physics—which physicists at the Large Hadron Collider use to describe particle interactions. In some amplituhedrons the amplitudes can be calculated directly. In others diagrams called “twistors” are needed.

What’s more, they’ve found the solution to everything. The volume of an infinite-sided “master amplituhedron” represents the amplitudes of all physical processes. The italics are supposed to impress you. Interactions between a finite number of processes, what us humans normally consider, are contained on various faces. Interesting to me, but probably not to anyone else, is that the master amplituhedron simplifies to a circle in 2D.


Amplituhedron representing an 8-gluon particle interaction, which normally needs ~500 pages of algebra.

The amplituhedron removes locality and unitarity. Particles that aren’t near either other in space or time can interact (what?) and the sum of the probabilities for all possible particle positions doesn’t have to be 1 (what?!). That works out for gravity though, which explodes—yes, explodes—in equations with locality and unitarity. Connecting gravity to particle physics is a big deal—no one’s been able to do it yet. Jacob Bourjaily, one of the researchers, described this method as “a starting point to ultimately describing a quantum theory of gravity.”

Nima Arkani-Hamed, the lead author (the main man, the head honcho), gave a talk about amplituhedrons at the SUSY 2013 conference, which is posted online. Warning: the talk is very technical, but interesting nonetheless (if only to watch a man in shorts and a shirt two sizes too large give a spitfire professional talk). Although, in the talk he says amplituhedrons can be “explained to a smart junior high school student,” which left me feeling like a stupid graduate student.