Hypothetical new particle could solve two major problems in particle physics

September 8, 2016 by Lisa Zyga, Phys.org feature
Using constraints from previous experiments, the physicists identified two regions, A and B (dotted), to search for the new particle in proposed experiments. Credit: Liu et al. ©2016 American Physical Society

(Phys.org)—Although the Large Hadron Collider's enormous 13 TeV energy is more than sufficient to detect many particles that theorists have predicted to exist, no new particles have been discovered since the Higgs boson in 2012. While the absence of new particles is informative in itself, many physicists are still yearning for some hint of "new physics," or physics beyond the standard model.

In a new paper published in Physical Review Letters, physicists Yu-Sheng Liu, David McKeen, and Gerald A. Miller at the University of Washington in Seattle have hypothesized the existence of a that looks very enticing because it could simultaneously solve two important problems: the puzzle and a discrepancy in muon measurements that differ significantly from predictions.

"The new particle can account for two seemingly unrelated problems," Miller told Phys.org. "We also point out several experiments that can further test our hypothesis."

The physicists describe the hypothetical new particle as an "electrophobic scalar boson." Currently there are five bosons in the standard model, only one of which is a scalar (the Higgs), meaning it has zero spin. All five bosons have been experimentally confirmed, and all are force carriers that play a role in holding matter together.

One of the distinct features of the new hypothetical particle is that, although it is predicted to bind to protons and neutrons, it would bind very weakly or not at all to electrons, making it "electrophobic." The scientists showed that this electrophobic property would allow the particle to solve both the proton and muon problems.

In the proton radius puzzle, the problem is that the proton radius seems to have a different size depending on what type of particle is orbiting it. Experiments have found that the proton radius is slightly larger when it is orbited by an electron than when it is orbited by a muon, which is identical to the electron except for being 200 times heavier. Assuming that the discrepancy is not due to measurement error (which it very well may be, considering how difficult it is to measure a particle that is less than a femtometer [10-15 meters] across), the results may point to the existence of a previously unknown fundamental force that pulls protons and muons closer together, but does not act between protons and electrons.

"The principle of lepton universality is a pillar of the standard model," Miller said, referring to the idea that all leptons, including electrons and muons, should behave in the same way. "Our particle violates this principle, because interactions with muons and electrons are different."

The second problem involves the muon's anomalous , which is a measure of how quantum effects contribute to the magnetic moment of a particle. So far, the most precise measurement disagrees with the standard model by more than three standard deviations. Once again, physicists think that the discrepancy may indicate physics beyond the standard model, or else more accurate measurements are needed. If the answer is new physics, then the new particle suggests that the proton and muon problems may be related.

"The proton radius puzzle can be explained if there is a new additional attractive interaction between the muon and proton," Miller said. "Such an interaction must also contribute to the muon anomalous magnetic moment. The proton radius puzzle (contribution to the Lamb shift) determines the strength of the interaction that contributes to the muon anomalous magnetic moment. The new contribution is just large enough to account for the current disagreement between theory and experiment. The equations in our paper allow us to obtain definite numbers, and these numbers can work out to be just right to account for both puzzles. New experiments will determine whether this is true physics or just a coincidence."

The physicists emphasize that they make no assumptions about the hypothetical particle other than that it could explain both of these puzzles. By constraining the mass of the using data from previous experiments, the physicists predict that its mass would lie somewhere between 100 keV and 100 MeV.

Although previous experiments have already explored part of this predicted range, the physicists have identified two unexplored regions that may be ideal places to look. They expect that future high-precision experiments involving protons and muons may be able to search for the particle in these regions.

"We constrain the parameter space (mass and couplings) of this new particle in a finite range (except for the coupling of electrons)," Liu said. "So experimentalists can discover or exclude it by looking at a specific place, instead of measuring zero more and more accurately, like in the electron experiments."

In the meantime, the physicists are also looking forward to improved measurements of the anomalous magnetic moment—if the discrepancy remains, the results will offer further support for the existence of the new particle. The scientists also plan to apply some of the methods they developed here to look for other new .

"Our work on this has allowed us to develop new theoretical tools to aid in the search for other kinds of bosons with different quantum numbers," Miller said. "We will be applying those tools. Another direction is to develop a deeper theory that accommodates our new boson."

Explore further: New measurement with deuterium nucleus confirms proton radius puzzle is real

More information: Yu-Sheng Liu, David McKeen, and Gerald A. Miller. "Electrophobic Scalar Boson and Muonic Puzzles." Physical Review Letters. DOI: 10.1103/PhysRevLett.117.101801. Also at arXiv:1605.04612 [hep-ph]

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27 comments

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NoStrings
1.3 / 5 (12) Sep 08, 2016
You mean fantasized? Have to publish paper on something, don't they? Publish or perish.

And here comes one more - to bite the dust next.
ursiny33
1 / 5 (4) Sep 08, 2016
You only have the tools to measure the dominant charge in particle mass , thats only part of a story of the particle, and if the particle even has a magnetically bonded smaller mass charge on it
Benni
1 / 5 (8) Sep 09, 2016
Come on, come on, just come on & knock it off pussy footing around with this meaningless nonsense about discovering some new feature about the "muon anomalous magnetic moment" & find the rest of the Universe for us.

What the hell, for almost a hundred years now, we've gotten these unending narratives about 80-95% of the Universe being MISSING, and all they can come up with for the future of Particle Physics is some dumb idea to research anomalous magnetic moments of muons?

When I look in a mirror, I want to know what the rest of my 80-95% Missing Mass looks like. Huh? Can you get your priorities straight?

tinitus
Sep 09, 2016
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tinitus
Sep 09, 2016
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tinitus
Sep 09, 2016
This comment has been removed by a moderator.
Benni
1.3 / 5 (6) Sep 09, 2016
OK Tin,

It's nice you have found all the Missing Mass. Now would you please report it to the researchers who are the subjects of this article? I mean, it is just the most unproductive thing imaginable that they continue aiming their Collider Beams in the wrong direction & miss coming up with the rest of the particles that make up 80-95% of the Universe.................in short Tin, I want to know what the rest of Phys 1 may look like.
Hyperfuzzy
1 / 5 (3) Sep 10, 2016
OK, so if we don't know, anything we imagine will do. Not my logic or science. I always begin with what is known then explain the energy spatial and time distribution, i.e. only measure the field response using stuff we know exist. Juz say'n
Hyperfuzzy
1 / 5 (3) Sep 10, 2016
OK Tin,

It's nice you have found all the Missing Mass. Now would you please report it to the researchers who are the subjects of this article? I mean, it is just the most unproductive thing imaginable that they continue aiming their Collider Beams in the wrong direction & miss coming up with the rest of the particles that make up 80-95% of the Universe.................in short Tin, I want to know what the rest of Phys 1 may look like.

Try defining mass with what we know. Maybe you might see that nothing is missing.
nikola_milovic_378
Sep 10, 2016
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nikola_milovic_378
Sep 10, 2016
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Benni
1 / 5 (5) Sep 10, 2016
Try defining mass with what we know. Maybe you might see that nothing is missing.
.........Asstro-physicists don't know how to do this, their education is so short on Nuclear Physics that if they actually got into the subject matter they would soon be "lost in space".
RNP
3.4 / 5 (5) Sep 11, 2016
@Benni

Try defining mass with what we know. Maybe you might see that nothing is missing.
.........Asstro-physicists don't know how to do this, their education is so short on Nuclear Physics that if they actually got into the subject matter they would soon be "lost in space


How many Asstro-physicists [sic] do you know? How familiar are you with their educational histories? You're not are you? You just invented this didn't you? Just because it fits your deluded view of science. Besides, NUCLEAR physics has nothing to do with it.
tinitus
Sep 11, 2016
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tinitus
Sep 11, 2016
This comment has been removed by a moderator.
tinitus
Sep 11, 2016
This comment has been removed by a moderator.
tinitus
Sep 11, 2016
This comment has been removed by a moderator.
RNP
1 / 5 (2) Sep 11, 2016
@tinitus
WOW!!!!! I can only admire your ability to produce such copious amounts of unmitigated nonsense.
Hyperfuzzy
1 / 5 (4) Sep 11, 2016
I see many sets of 2 unique diametrical spherical field centers, never created, never destroyed. I deny any other creation other than an event in the field of a group of any of these with a defined state, i.e. known physics, not GR, not SM, not DM, not BB, not SS, maybe QM & not quanta. So no particles!
RNP
1 / 5 (2) Sep 11, 2016
The crazies are out in force tonight!
Hyperfuzzy
1 / 5 (2) Sep 11, 2016
The crazies are out in force tonight!

Maybe you are right, how do you define your measurements?
Benni
1 / 5 (5) Sep 11, 2016
How many Asstro-physicists [sic] do you know? How familiar are you with their educational histories? You're not are you? You just invented this didn't you? Just because it fits your deluded view of science.


In my field of Nuclear/Electrical Engineering we have a very succinct definition of an Asstro-physicist as someone who knows everything there is to know about anything that doesn't exist.

Besides, NUCLEAR physics has nothing to do with it.
.........that's for sure, Albert Einstein was a Nuclear Physicist, tired zany Zwicky & Schwarzschild along with his Black Hole Math were Asstro-physicists.........do that math.

RNP
5 / 5 (2) Sep 13, 2016
@Benni
.........that's for sure, Albert Einstein was a Nuclear Physicist, tired zany Zwicky & Schwarzschild along with his Black Hole Math were Asstro-physicists.........do that math.


Wrong on most counts:

Albert Einstein was not a "Nuclear Physicist".

Schwarzschild was not an astrophysicist, he was a physicist who just happened to also worked in astrophysics.

Just inventing things to match your delusions will not wash here.
Koen
1 / 5 (1) Sep 13, 2016
"electrophobic scalar boson", what a politically correct type of scalar boson that is. It is probably one of those useless new particles. As if we do not know how much impact a scalar field that interacts with the electric field can have on our economy.
Hyperfuzzy
1 / 5 (2) Sep 13, 2016
The problem with particle physics is that a particle has no definition. I propose that the particles we call protons and electrons, are not particles at all. They are the field, the centers we've named, but ignored the beautiful body, everywhere, for all time with a center, defined. Nothing else. All particles are created from these, not the other way around.
optical
Sep 16, 2016
This comment has been removed by a moderator.
Hyperfuzzy
not rated yet Sep 16, 2016
An https://imgs.xkcd...xion.png for contemporary physics..

What does that mean?

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