The thing with physicists is that they love discovering something unexpected, strange or exotic. This mindset is what makes physics, and indeed all science disciplines, awesome. But in light of the grand announcement of the probable discovery of the elusive Higgs boson in July, it looks like the particle that was discovered is likely a “standard” Higgs boson. As in, it’s a little bit boring.
Of course, “boring” is a relative term. The story of the hunt for the Higgs — the ‘exchange particle’ that endows matter with mass — reads like a Dan Brown novel, culminating in the construction of the biggest, boldest and most complex machine mankind has ever conceived: the Large Hadron Collider (LHC). There’s more twists, turns and subplots than you can shake a lepton at.
But the famous Higgs boson, that until recently has been purely a theoretical particle only appearing in equations, looks like it comes from the Standard Model of physics and not something more exotic.
The Standard Model is a set of equations and particles that underpin our known Universe. It’s a recipe book of sorts and works like this: If you collide particle A with particle B you get particle C plus some energy — we know what will come out of a particle interaction even before the interaction takes place. There’s nothing unexpected in this recipe book; so it doesn’t work like this: If you collide particle A with particle B you get particle Q and — what the #$%@?! — a small elephant playing with a black hole!
The latter scenario would violate our known laws of physics, suggesting something more exotic is going on. In that case, there would be some kind of new physics, something beyond the Standard Model at play — perhaps an exotic result from the LHC would provide evidence of “supersymmetry.” One interpretation of supersymmetry suggests there may be an entire family of Higgs bosons that cannot be explained by the Standard Model. However, supersymmetry has recently been dealt a “hospitalizing” blow.
So particle physicists have been wondering, is the signal of the Higgs representative of a Standard Model Higgs (i.e. a particle that is completely predicted by the equations described by the Standard Model) or are some exotic physics at play?
In new results presented at a particle physics conference in Kyoto, Japan, on Wednesday, physicists of the ATLAS and CMS experiments at the LHC revealed that there’s little strange or unexpected with the behavior of the Higgs boson they have detected in their data. This is basically confirmation that the equations formulated by Peter Higgs and his colleagues over 50 years ago correctly describe the Higgs boson. Few signs of exotic physics have, so far, been detected.
“The (Higgs boson) is still there, and it’s certainly staying consistent with the Standard Model,” said Joe Incandela, lead physicist of the CMS detector team.
In July, when LHC physicists initially made their announcement, there were signs that the particle they’d detected could have some exotic properties.
The Higgs boson is naturally very unstable — one of the reasons why it has been so elusive. When it decays, the Standard Model predicts that it should produce a certain number of tau particles (heavy cousins of the electron). But the data suggest an excess of gamma particles were being generated. At the time, this discrepancy was too small to make any conclusions, so more experiments were carried out. Wednesday’s announcement didn’t modify this slight discrepancy, but, again, no conclusions can be drawn.
Therefore, the Standard Model still holds true for the Higgs, but there is a tiny element of weirdness going on that might reveal some exotic physics and the Higgs may not be quite acting as it should.
“The Standard Model still rules OK, but the main test will come when the gamma rates are updated,” said John Ellis, theoretical physicist and former head of theory for CERN.
But in this grand game of cat and mouse in the quantum world, discoveries of new physics (or confirmation of tried and tested physics) take years or even decades to confirm, so we might be in for a long wait. Although there are indications that the Higgs particle is born from the Standard Model, the quest to understand its true nature is anything but “boring”; it’s one of mankind’s most profound challenges.
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