Mounting evidence for a 95 GeV Higgs boson
arxiv.org
arxiv.org
There is a very strong experimental support for the "old" Higgs Boson discovered in 2012 that has a mass of 125Gev, and there is some recent weak experimental support for another "new" Higgs Boson with a mass of 95GeV. (For comparison, the mass of a proton is ~0.9GeV.)
In this preprint, they propose that there is a family of tree Higgs Bosons. The "old" one, the "new" one and a third one yet to be detected. The structure of the family forces some of the properties of the bosons and how they interact with the other particles.
The hard part is tweaking the properties of the family of Higgs Bosons so they predict the results of the experiments where the 125GeV and 95GeV are seen, but they don't cause weird results in all the other thousands of experiments where the Higgs Bosons have a negligible effect.
I thought the Higgs was what gave other particles mass?
How can it be heavier than the particles it gives mass to?
By the way, here's a metaphor I like for how a field gives a particle mass. Compare throwing a ball at a given speed underwater vs in the air. In the water it will sink more for a given horizontal distance. The horizontal distance is like motion in space; the vertical distance is like motion in time. For less dense particle, the particle falls more over a given distance in space (because it is slowed down a lot). That's basically what mass means: moving through the field forces you to spend time (vertical distance in this case) to cover space (horizontal distance). Whereas a 'massless' particle would be one that doesn't interact at all with water, and passes through it unaffected.
(It's not a perfect model. There's nothing like 'gravity' acting on particles in this way. But I think it's a reasonably intuitive idea of what a 'field giving a particle mass' could mean.)
Sorta yes, but it's more complicated.
> How can it be heavier than the particles it gives mass to?
There are a few bad explanations about the Higgs boson floating around. I hate all of them. I wish I can write a good one, but it's very difficult task.
One of the explanations is the "prime minister" analogy, that says that the usual particles are like a prime minister, and the Higgs bosons are like the press reporters that follow the prime minister around. So even if the prime minister has no mass, the big bundle of the prime minister and the journalist has mass. In this explanation it's difficult to imagine why the mass of the bundle is smaller than the mass of each journalist. [Did I already said that I hate this explanation?]
Oversimplifying toooo much:
The idea is that the usual particles have something that look like mass because they bounce against the Higgs boson. They don't absorb the Higgs boson. They are not surrounded by Higgs bosons. They just bounce against a Higgs boson from time to time, and that somehow cause that they look like particles with mass. It's weird, very weird. The analogy does not give an intuitive explanation, but this can be formalized and the equations model the experiment accurately.
But actually, the usual particles are not bouncing against Higgs boson, they are bouncing against the non-zero vacuum expectation value Higgs field. What is the Higgs field? What is the vacuum expectation value? Why it is not zero like in most fields? Those are hard questions!
I watched the video in Encyclopædia Britannica linked in the sibling comment, and it's quite good. I hope it makes thing more clear than my explanation.
What's your opinion on the PBS spacetime explanation?
https://www.youtube.com/watch?v=kixAljyfdqU
I've discovered the channel only recently, and have been binge-watching since.
I'll compare this video with https://www.britannica.com/video/185531/explanation-field-Hi... that was linked in a sibling comment by harshreality.
The PBS video:
* Has more technical stuff, so I'd recommend to see the other video first.
* I like that it explain chirality. It's very important for this subject.
* I don't like that they say that massless particles "experience no time". It's a common idea floating around, but it cause more misinterpretations than what it helps in the explanations.
* They explain hypercharge. It's really important, but I'd hide under the carpet because there are too many things to explain.
* In particular the circle in 5:22 is misleading/wrong. IIRC it's not a circle (aka U(1)), it's a magic double sphere (aka SU(2)). A circle is a nice representation, but they put a "real" and a "imaginary" axis in the graph, as it were actually the circle in the complex plane. This part is also important, and specialist love it because spontaneous symmetry breaking is so unusual and weird, but I'd just hid it under the carpet too.
* The idea that the "spin constantly flips back and forth" is wrong. The spin is stable. For example the left handed (L) version of the electron and the right handed (R) version have spin 1/2. If you take a particle with spin +1/2 in one direction, the L and R version "flips back and forth" but when you measure the spin again in the same direction you still get +1/2, because the spin does not change.
What "flips back and forth" is the direction. The idea is very similar to what is explained in the video in Britannica. If you mix different amounts of L and R with spin +1/2 in one direction, you can get a particle that has spin +1/2 in that direction and any speed you like because the speed is something like the average of both speeds. The Higgs field somehow keep the L and R version together, instead of them flying away in oposite directions. For this part I strongly prefer how it is explained in the video in Britannica.
It's a nice video, but they should fix the part about spin flipping. (And perhaps hide the some details, but this is a personal preference.)
https://www.britannica.com/video/185531/explanation-field-Hi...
What is the field?
Some boats have sleek hulls and so the water doesn't slow them down too much. These are particles without much mass.
Some boats have a few barnacles on their hulls. These are particles with more mass.
The analogy is imperfect: if you give a boat a single push it will come to a stop, losing energy to the water; if you give a particle a push through the Higgs field it keeps going, it is not possible to give your momentum to the vacuum.
These don’t sound like “risky predictions” at all! We already know everything that the model should output?
Popper is spinning in his grave. And a real theoretical physicist would have been able to tell you “95GeV” before seeing it.
The fist graph shows how many times an experiment produced a pair of photons. The x axis is the energy of the photons, and the y axis is the number of events (I'm not sure about the scale here).
The dashed line is the theoretical result without the second boson IIUC. The green zone is the range of a difference of ±σ. The yellow zone is the range of a difference of ±2σ.
The continuous line is the experimental data. As expected, the experimental data is close to the theoretical result, but it is not exactly equal. It moves most of the time in the green zone of ±σ. Sometimes it moves in the yellow zone of green zone is the range of a difference of ±2σ. The interesting part is that in some parts it goes outside the yellow some. For those energies the theoretical model is too different of the experimental data.
Back to your objection, the idea in the paper is to make a model with a few parameters, and then optimize the parameters until the curve of the new model fits the experimental data as much as possible.
It's not enough to say 95GeV, the model has more parameters and also they must verify that the new model modifies the range of energies where the difference is big, but does not modify too much the other ranges.
At this point, there is basically nothing to see here. You will do yourself a favor by just moving along.
Isn't the fact that they were explicitly hunting for it a reason to take it more seriously? In contrast, if this signal was discovered after trawling the huge dataset for a hundred possible hypotheses, that would be a reason to discount it, Bayes-wise.
There are a lot of alternatives that involve more Higgs Bosons https://en.wikipedia.org/wiki/Higgs_boson#Alternative_models and the models have some internal parameters to adjust, but it's very difficult to guess which one is the correct (or if the correct one is the simplest one) until more Higgs bosons are discovered (or someone has an extraordinary brilliant idea).
It's a lot like: two atoms can always exchange a low-energy photon, say, and move an electron between orbitals... but they could also exchange a _super high energy photon_ instead. It's just very highly unlikely. Nevertheless the fact that they can do that contributes to the physics, at least a little bit. But that virtual high energy photon (which shows up in the Feynman diagrams) isn't destroying anything either, for the same reason the Higgs isn't.