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Posted on 10/29/2021 5:05:04 AM PDT by Kevmo
New Force of Nature? Tantalizing Evidence for New Physics From CERN’s Large Hadron Collider
University Of Cambridge By HARRY CLIFF, UNIVERSITY OF CAMBRIDGE OCTOBER 26, 2021
Particle Accelerator Physics Concept
The Large Hadron Collider (LHC) sparked worldwide excitement in March as particle physicists reported tantalizing evidence for new physics — potentially a new force of nature. Now, our new result, yet to be peer reviewed, from CERN’s gargantuan particle collider seems to be adding further support to the idea.
Our current best theory of particles and forces is known as the standard model, which describes everything we know about the physical stuff that makes up the world around us with unerring accuracy. The standard model is without doubt the most successful scientific theory ever written down and yet at the same time we know it must be incomplete.
Famously, it describes only three of the four fundamental forces – the electromagnetic force and strong and weak forces, leaving out gravity. It has no explanation for the dark matter that astronomy tells us dominates the universe, and cannot explain how matter survived during the big bang. Most physicists are therefore confident that there must be more cosmic ingredients yet to be discovered, and studying a variety of fundamental particles known as beauty quarks is a particularly promising way to get hints of what else might be out there.
Beauty quarks, sometimes called bottom quarks, are fundamental particles, which in turn make up bigger particles. There are six flavors of quarks that are dubbed up, down, strange, charm, beauty/bottom and truth/top. Up and down quarks, for example, make up the protons and neutrons in the atomic nucleus.
LHCb Experiment Cavern The LHCb experiment at CERN. Credit: CERN
Beauty quarks are unstable, living on average just for about 1.5 trillionths of a second before decaying into other particles. The way beauty quarks decay can be strongly influenced by the existence of other fundamental particles or forces. When a beauty quark decays, it transforms into a set of lighter particles, such as electrons, through the influence of the weak force. One of the ways a new force of nature might make itself known to us is by subtly changing how often beauty quarks decay into different types of particles.
The March paper was based on data from the LHCb experiment, one of four giant particle detectors that record the outcome of the ultra high-energy collisions produced by the LHC. (The “b” in LHCb stands for “beauty.”) It found that beauty quarks were decaying into electrons and their heavier cousins called muons at different rates. This was truly surprising because, according to the standard model, the muon is basically a carbon copy of the electron – identical in every way except for being around 200 times heavier. This means that all the forces should pull on electrons and muons with equal strength – when a beauty quark decays into electrons or muons via the weak force, it ought to do so equally often.
Instead, my colleagues found that the muon decay was only happening about 85% as often as the electron decay. Assuming the result is correct, the only way to explain such an effect would be if some new force of nature that pulls on electrons and muons differently is interfering with how beauty quarks decay.
The result caused huge excitement among particle physicists. We’ve been searching for signs of something beyond the standard model for decades, and despite ten years of work at the LHC, nothing conclusive has been found so far. So discovering a new force of nature would be a huge deal and could finally open the door to answering some of the deepest mysteries facing modern science.
New results While the result was tantalizing, it wasn’t conclusive. All measurements come with a certain degree of uncertainty or “error.” In this case there was only around a one in 1,000 chance that the result was down to a random statistical wobble – or “three sigma” as we say in particle physics parlance.
One in 1,000 may not sound like a lot, but we make a very large number of measurements in particle physics and so you might expect a small handful to throw up outliers just by random chance. To be really sure that the effect is real, we’d need to get to five sigma – corresponding to less than a one in a million chance of the effect being down to a cruel statistical fluke.
To get there, we need to reduce the size of the error, and to do this we need more data. One way to achieve this is simply to run the experiment for longer and record more decays. The LHCb experiment is currently being upgraded to be able to record collisions at a much higher rate in future, which will allow us to make much more precise measurements. But we can also get useful information out of the data we’ve already recorded by looking for similar types of decays that are harder to spot.
This is what my colleagues and I have done. Strictly speaking, we never actually study beauty quark decays directly, since all quarks are always bound together with other quarks to make larger particles. The March study looked at beauty quarks that were paired up with “up” quarks. Our result studied two decays: one where the beauty quarks that were paired with “down” quarks and another where they were also paired with up quarks. That the pairing is different shouldn’t matter, though – the decay that’s going on deep down is the same and so we’d expect to see the same effect, if there really is a new force out there.
And that is exactly what we’ve seen. This time, muon decays were only happening around 70% as often as the electron decays but with a larger error, meaning that the result is about “two sigma” from the standard model (around a two in a hundred chance of being a statistical anomaly). This means that while the result isn’t precise enough on its own to claim firm evidence for a new force, it does line up very closely with the previous result and adds further support to the idea that we might be on the brink of a major breakthrough.
Of course, we should be cautious. There is some way to go still before we can claim with a degree of certainty that we really are seeing the influence of a fifth force of nature. My colleagues are currently working hard to squeeze as much information as possible out of the existing data, while busily preparing for the first run of the upgraded LHCb experiment. Meanwhile, other experiments at the LHC, as well at the Belle 2 experiment in Japan, are closing in on the same measurements. It’s exciting to think that in the next few months or years a new window could be opened on the most fundamental ingredients of our universe.
Written by Harry Cliff, Particle physicist, University of Cambridge.
This article was first published in The Conversation.The Conversation
“Have any astronomers actually proven this stuff exists?”
Their model is a continually shifting bag of assertions that change when new data is discovered to change the model.
I don’t see any beauty quarks on her…..
I wonder how long it’s going to take the Chicoms to get their hands on that collider.
Upton quark?
Since it started out as the Bottom Quark instead of calling it the Beauty Quark, shouldn’t they call it the Booty Quark?
I think this is just bad physics terminology like spin not really meaning spin. Any time a particle changes into other particles the physicists call it decay.
# Have any astronomers actually proven this stuff exists?
No. It is inferred. Personally, I don’t buy it.
In the very beginning expansion phase of our universe, many things were faster than light. The universe itself expanded faster than light, primarily because matter wasn’t yet matter and light wasn’t yet light.
In fact, there is evidence that light itself was faster than light, that it is a decaying function — well after the initial expansion phase. https://freerepublic.com/focus/news/2270920/posts
Stay on the path and search for new God created forces.
***Yes, well said. I wonder how soon we’ll see the discovery of the force that holds dark matter in its place.
Indeed! I love science. The search for Dark Matter always draws my attention.
"To get there, we need to reduce the size of the error, and to do this we need more data."
Translation:
Probably another of those "famous" disappearing discoveries...
Please keep giving us those billions of euros so we can fiddle around with old data some more...
We do need a bigger version of the LHCb...
We looked at the data and broke out in the particle-physics song: "You are so beautiful"...
In my day, we'd have used the term GIGO...
Kate confounds scientists by being simultaneously an beauty/bottom, innie/middle and beauty/top characteristics.
It is not as in the old days when you could remember the author of a paper. The authors from the LHCb collaboration are listed in small print on pages 17 - 20 https://arxiv.org/pdf/2110.09501.pdf
OK, thanks. I didn’t realize that. So could it be that when that quark decays into an electron (about 200 times lighter than a muon), that electron is moving very fast as opposed to a muon it would change into? To “make up” for the missing mass, so to speak?
BTW, it turns out that due to the uncertainties of quantum mechanics that the number of possible particle transformations is infinite leading to infinities showing up in a lot of the equations. These pesky infinities have to be "normalized" out of the equations in order for them to be useful. This is still a somewhat controversial procedure to this day. So QM is still on somewhat shaky ground despite its seeming ability to be very accurate in certain situations.
Somewhere there is probably a list, or better yet diagram, that shows all of the ways that particles can change into other particles.
***I saw an interaction chart like that once, when Antony Garrett’s e8 theory was being discussed. But I can’t find it now...
https://en.wikipedia.org/wiki/An_Exceptionally_Simple_Theory_of_Everything
These pesky infinities have to be “normalized” out of the equations in order for them to be useful.
***Does that mean our universe is a deforming mathematical lie group?
https://arxiv.org/pdf/1506.08073.pdf
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