Freedom from Symmetry: Six Years of the Higgs Particle

A “cephalopod diagram” of Higgs decay, with vector boson final states in red and fermion final states in blue. Solid lines correspond to final states we’ve definitely seen, and dashed lines represent final states still being hunted. The area of a circle represents its relative rate to that of the bottom-quark final state, which is expected to represent 60% of all Higgs boson decays.

Six years ago on this date, the Higgs boson was (probably) discovered by the ATLAS and CMS Experiments at the Large Hadron Collider in Geneva, Switzerland. I say “probably” because, at the time, all we really knew for sure was that we had discovered a new particle, with a particular mass (about 126 times the proton mass, at the time), that appeared in our experiments in ways consistent with, but not unique to, the predicted Higgs particle.

Well, it’s been 6 years and 1 Nobel Prize in physics since then, and we’re all pretty darn sure it is the Higgs boson predicted in the early 1960s.

But wait. Is it? ATLAS and CMS continue to map out its detailed properties, including one of the biggest sets of prizes in the current data set being collected right now: how much the Higgs boson interacts with the top quark, the heaviest of the 6 known quarks, and the bottom quark, the second-heaviest quark. It’s an unfolding story.

Meanwhile, check out these blog posts from me back in July of 2012, and remind yourself of how glorious it is to see something no one has ever seen before.

Relive the moments before and after the announcement of the “bump” in the data from my friend, Aidan Randle-Conde, who was at the time a post-doctoral researcher at SMU and an avid blogger and science communicator:

“Reality in the Shadows (or) What the Heck’s the Higgs?” is meant to help a new audience come to discover a love of science and especially physics, or to welcome to the frontier those who already discovered that love a long time ago.

And, of course, with further hindsight and many more years of data to inform the discussion, learn more about just what the heck’s the Higgs in our book, “Reality in the Shadows (or) What the Heck’s the Higgs?” by S. James Gates, Jr., Frank Blitzer, and me!

While we know more about this particle since discovering it in 2012-2013, there are many mysteries left. Some prizes are big, but hard to claim in all the noise. For instance, only just a year ago, we spotted the first strong hints of the direct interaction of the Higgs particle and the bottom quark… despite the fact that this should be its favored method of decay! Learn more here:

UPDATE (July 6, 2018): Added the really nice “post-seminar analysis video” from Aidan and some more words about how data in the intervening years has shed light on some questions but left others open.

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