Roger's Equations Blog

Roger's Equations

This blog is all about science and technology (with occasional math thrown in for fun). The goal of this blog is to try and pass on the sense of excitement and wonder I feel when I read about these topics. I hope you enjoy the posts.

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Three Generations of Fermions Are Enough

Posted November 30, 2015 8:16 AM by Bayes

I came across this interesting article which suggests it is highly unlikely there are more than the currently observed three generations of Fermions.

Here is the article:

12 matter particles suffice in nature: Limited number of fermions in standard model, physicists say

Matter particles, also called fermions, are the elementary components of the universe. They make up everything we see on earth or through telescopes. "For a long time, however, it was not clear whether we know all components," explains Ulrich Nierste, Professor at KIT. The standard model of particle physics knows 12 fermions. Based on their similar properties, they are divided into three generations of four particles each. Only the first generation of particles occurs in appreciable amount outside of particle accelerators. Among these particles are the electron, the electron neutrino, and the up-quark and down-quark. Up- and down-quarks form heavier particles, such as protons and neutrons and, hence, all elements of the periodic system. "But why does nature have second and third generations, if these are hardly needed? And are there maybe more generations of particles?," ask the main authors of the article, Martin Wiebusch and Otto Eberhardt. At least, the latter question is answered: "There are exactly three fermion generations in the standard model of particle physics!"

For their analysis, the researchers combined latest data collected by the particle accelerators LHC and Tevatron with many known measurements results relating to particles, such as the Z-boson or the top-quark. The result of the statistical analysis is that the existence of further fermions can be excluded with a probability of 99.99999 percent (5.3 sigma). The most important data used for this analysis come from the recently discovered Higgs particle. The Higgs particle gives all other particles their mass. As additional fermions were not detected directly in accelerator experiments, they have to be heavier than the fermions known so far. Hence, these fermions would also interact with the Higgs particle more strongly. This interaction would have modified the properties of the Higgs particle such that this particle would not have been detected. With the exclusion of the fourth fermion generation the first open question of particle physics is now answered by the measurements made at the new LHC particle accelerator ring of CERN.

Article Found Here

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#1

Re: Three Generations of Fermions Are Enough

11/30/2015 9:18 AM

Now if we could just build something that has no Higgs particles, we could defy gravity....

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Re: Three Generations of Fermions Are Enough

11/30/2015 2:19 PM

..."Now Petersson's team has suggested that, if supersymmetry is real, the Higgs boson may have another mode of decay, disintegrating into photons and dark matter particles. And the LHC's ATLAS and CMS experiments are on the look-out for this theorized decay mechanism."

http://news.discovery.com/space/the-higgs-boson-may-disintegrate-into-dark-matter-150203.htm

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#3

Re: Three Generations of Fermions Are Enough

12/01/2015 7:24 AM

The collider looks so common Roger, I wonder if there were any resemblance. ;)

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