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Alas, the Large Hadron Collider didn't find a new particle after all

Alas, the Large Hadron Collider didn't find a new particle after all


We won't be rewriting physics books just yet

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At the end of last year, physicists working with the Large Hadron Collider thought they may have discovered a brand-new type of particle that could completely change our understanding of physics. But it looks like our understanding of physics won’t be drastically altered today. In new LHC measurements, the data that pointed to this new exotic particle have vanished, indicating that the initial measurements may have just been a fluke, New Scientist reports.

Our understanding of physics won’t be drastically altered today

The hubbub started in December when two scientific collaborations at CERN — ATLAS and CMS — both found similar statistical blips in their LHC data. The LHC is the world’s most powerful particle accelerator, where high-energy beams of protons and ions slam into each other at close to the speed of light. The goal is to study the debris created from these collisions to get a better understanding of the particles that make up our Universe.

Last year, both CMS and ATLAS saw some strange products from these particle collisions: a bunch of proton-pairs with a combined energy of 750 gigaelectronvolts (GeV). The data was tantalizing, as it pointed to the existence of a massive new particle. The idea was that LHC collision produced a particle weighing 750 GeV, which then decayed into two protons of the same energy, according to Nature. If that was the case, the particle would have been the largest particle discovered to date.

There were many reasons to be excited by the data

There were many reasons to be excited by the data. First, the results were found by two different scientific collaborations, which helped to strengthen the argument that these weren’t just statistical anomalies. Additionally, the findings appeared as bumps in the CMS and ATLAS data, and a similar data bump pointed to the existence of a 125 GeV particle back in 2012 — the famous Higgs boson. However, scientists had been expecting to find the Higgs boson because its existence had been predicted by the Standard Model, which describes all the different ways that particles can interact. This new 750 GeV particle didn’t quite fit into that model, which means its existence would have completely rewritten the rulebook.

But now, new data from the CMS collaboration no longer supports the 750 GeV particle. The bump that was seen before is completely gone from the new data. "So — it seems that what we saw in those December plots was a fluke," wrote Matt Strassler, a theoretical physicist and visiting professor at Harvard, in a blog post. "It happens. I’m certainly disappointed, but hardly surprised. Funny things happen with small amounts of data."