Chapter 629 Look what we found? (Part 2)
More than half an hour ago.
Xu Yun was still feeling a little emotional that Zhao Zhongyao and Gell-Mann missed each other. After all, these two people were actually quite compatible.
And although Xu Yun didn't like Gell-Mann as much as he did Weinberg, he couldn't say he disliked him - among the many big guys, Gell-Mann was considered one of the more friendly to China.
For example, he often comes to China to give lectures, and he only talks about academics and not politics, nor does he belittle the Chinese scientific community.
There are other physicists who have been to China more often than him, but firstly, their status is not as good as his, and secondly, these people are basically foreign academicians from China.
And there are many so-called foreign academicians.
Not to mention that they are all just for money.
At least except for R. Clough and David Gross, two foreign academicians who hardly ask for anything but have been donating to China, the rest of the foreign academicians basically want something.
For example, they are either the link between universities to maintain relationships, or they have cooperation with certain institutions, or they are simply mascots in name only.
Only Gell-Mann is neither a foreign academician nor has any business in China. He often comes to China to give lectures to impart some knowledge and then leaves - and the appearance fee is really not high.
For example, when he came to China in 2012, he only charged US$5,000 for a lecture, which was cheaper than his lectures at Ivy League schools.
Therefore, Xu Yun's view of Gell-Mann has always been neutral and friendly. Especially after Gell-Mann's death, the halo of the deceased gave Xu Yun a little more respect.
But what Xu Yun didn't expect was.
Now it seems that Mr. Gelmangai in this timeline may not be able to reach the heights of the original timeline.
After all
The concept proposed by Zhu Hongyuan is infinitely close to the quark model.
That's right.
Quark model - and some concepts independent of the stratoton model.
As everyone knows.
The strong force between quarks and gluons becomes weak not only over tiny time and distance intervals, but also over huge changes in energy and momentum.
These two behaviors are two aspects of asymptotic freedom. Later QCD uses quantum mechanical equations to deduce one from the other.
Rare and huge changes in energy and momentum will lead to the emergence of an astonishing phenomenon. This phenomenon was even recognized as a major feature of ultra-high energy interactions in Xu Yunlai's later generations.
That is.
The jet injection phenomenon is called jet in English.
Not an exaggeration.
The jet phenomenon reveals the essence of QCD, demonstrating quarks, gluons and the basic interactions between them in an extremely intuitive and visible form.
Students who have watched "Into Unscience" should know this.
Neutrons are made up of two down quarks and one up quark.
Pi mesons are composed of up quarks, down quarks and their antiparticles.
The proton is made up of two up quarks and one down quark.
In some high-speed collisions, the quarks may break away from their accustomed environment, gain a large amount of energy and momentum, and then leave the proton.
However, isolated quarks cannot persist because all quarks carry a "color charge" - which can be understood as a physical quantity similar to electric charge.
This non-zero color charge disturbs the balance of the color gluon field, so the quarks radiate the gluons, releasing energy and momentum.
These radiated gluons will in turn radiate other gluons, or quarks and antiquarks.
This way.
The initial stimulus eventually leaves behind a chain of quarks, antiquarks and gluons, which in turn condense into protons, neutrons and other hadrons.
This is a very complicated process, a bit like a mother giving birth to a daughter, and the daughter giving birth to a mother - this is the chaotic structure brought about by asymptotic freedom.
Then in this case.
All particles in a jet tend to move in the same direction.
Finally, the accelerator's detection equipment will observe the trajectories of many particles in a narrow cone-shaped space. This image is a jet - to put it bluntly, it is the shape of Splatoon after eating too much Wallace.
And because energy and momentum are conserved, the energy and momentum of all particles in the jet add up to the energy and momentum of the initial quark.
Jets are a perfect gift for physicists because they encode information about the energy and momentum of the initial particle.
In a sense, the jet is the embodiment of these particles.
in the original history.
The discovery of the three-jet injection was made by Mr. Ting Zhaozhong, more than ten years later.
At that time, Ding Zhaozhong led a team to discover a new elementary particle at Apuchin National Bluhaven Laboratory. This new particle is very unique, uncharged, and has a lifespan 1,000 times longer than the new particles discovered one after another in recent years.
So Ding Zhaozhong named it J particle. The word J is very close to Ding, and its meaning is self-evident.
When this particle was discovered, it also verified the correctness of the quark model proposed by Gell-Mann in 1964.
Also, it's a coincidence.
On the same day, the Richter Group at the Stanford Linear Accelerator also discovered a new particle, named the ψ particle.
What's even more interesting is that these two kinds of particles are actually the same thing, but both groups are humbly unwilling to compete for ranking and naming rights. Instead, they call the new particle after the other party's name.
Therefore, this particle is still called the "J/ψ meson" and is the only particle with two letters. Ting Zhaozhong and Richter also jointly won the Nobel Prize in Physics in 1976.
In addition, since meson is mentioned, here is another very funny joke:
If you search on Baidu for the question "Is the meson a fundamental particle?", you will find that the answer is "yes".
What’s even funnier is that when you click on the answer, you can see a sentence hanging at the front:
[Mesons are composed of a quark and an echoing antiquark, which are connected together through strong interactions to form this composite particle] - Don’t you find these last four words dazzling?
These days, a certain browser is really getting more and more outrageous, rogue and anti-intellectual, and is almost on par with Visual China.
His eyes returned to reality.
Of course.
The J particle collision energy level discovered by Ting Zhaozhong is 3.1 GeV, which far exceeds the level of the current tandem electrostatic accelerator.
Therefore, now Zhu Hongyuan and others will definitely not be able to find specific particles, they can only discover phenomena.
But don’t forget.
Zhu Hongyuan and others already had the prototype of the stratotron model at this time.
Although he did not see the actual J particles, he would definitely connect the particles he imagined with the stratoton model, that is, quarks.
In other words.
This phenomenon can be a strong support for the stratoton model!
This is much more important than J particles. After all, J particles are just subatomic mesons, not even elementary particles.
The stratoton model affects the entire basic particle framework!
Which is more important, a bed or a foundation, even a fool can tell the difference.
And just as Xu Yun was thinking.
Zhao Zhongyao on the side also spoke. He touched his chin thoughtfully and asked Zhu Hongyuan:
"Comrade Hong Yuan, do you mean that there is a smaller particle beneath the hadrons?"
Zhu Hongyuan pondered for a moment, but did not say anything too absolute:
"How can I say that if it is smaller than a hadron, it must not have escaped - after all, it was knocked out from the inside of the proton, and the proton is also a kind of hadron."
"But how much smaller it is than ordinary hadrons is unknown. What is certain at present is that its state must be very unstable."
"Either it cannot exist independently for some reason, or it will decay in a very short time - even at the particle level, it is still very short."
"Of course, the premise of the above speculations is that the particle is not a imaginary virtual object. In short, I personally think that this probability is very high - it just fits in with some concepts discussed in the group at the Institute of Atomic Energy at the beginning of the year."
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Upon hearing this, Zhao Zhongyao and Wang Ganchang looked at each other, and then asked Zhu Hongyuan:
"Comrade Hong Yuan, are you referring to the review of the metahadron model submitted by the Institute of Atomic Energy this year?"
Zhu Hongyuan nodded calmly. This question did not allow him to be conservative, and he admitted simply:
"That's right, it's the meta-hadron model."
Zhao Zhongyao was silent for a moment.
The Yuanqiangzi mentioned by Zhu Hongyuan and Zhao Zhongyao is the stratotron model that Xu Yun is familiar with. However, at this time, it has not been renamed as Stratum. The name verbally and in documents is called "Yuanqiangton".
Tell the truth.
Zhu Hongyuan's explanation is not supported by any data, and is more of a theoretical derivation.
But at least from Zhao Zhongyao's perspective, this statement can indeed explain the injection phenomenon.
Seeing that many people at the scene had blank expressions, Zhu Hongyuan coughed lightly and took the initiative to introduce the meta-hadron model:
"Comrades, I wonder if you understand the eight-fold method proposed by Mr. Gell-Mann and Mr. Neiman at the beginning of this year to classify hadrons using the SU(3) symmetry of the strong interaction?"
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"Eight-fold method?"
Lao Guo on the side was slightly startled when he heard this, then thought of something and recalled:
"Is that the method of assigning different singular numbers to different particles and combining eight particles to form a stable state?"
"If I remember correctly, there is a paper on this concept in the batch of foreign literature we got back from Guide County."
Zhu Hongyuan nodded towards Lao Guo and said:
"Yes, that's the method."
"Gong Guo, our Atomic Energy Institute got this paper in February this year. According to discussions among the team members at that time, everyone thought it was a very interesting concept."
"So we had free discussions based on this idea, and finally we came up with a model that, well, is a bit like an onion that can be peeled off layer by layer."
"Don't we have a concept of yuan in Chinese culture - for example, people have vitality and so on, so we called this model yuan hadron."
Mentioned earlier.
The foreign language documents that Lao Guo and the others retrieved back then were as large as an iron box. The accumulation of these documents took a certain time span, that is, they would only be "shipped" after a certain amount was reached.
Therefore, although these materials are precious, they lack some timeliness.
As for Zhu Hongyuan and his atomic energy institute, which was located in the capital, it was not difficult to get one or two journals in time through some scattered connections in Mao Xiong.
So before Lao Guo and the others received the foreign journal, Zhu Hongyuan and the others had already seen Gell-Mann's paper and even brainstormed.
Eightfold method.
This is a theory of strong symmetry of action proposed by Gell-Mann at the beginning of this year based on the idea of symmetry.
He pointed out that strongly interacting particles should satisfy SU(3) symmetry, which corresponds mathematically to the SU(3) group.
Taking into account the reading needs of some stupid students who come here to master knowledge, here is a brief explanation of the concepts of several groups:
in particle physics.
The three groups SU(1), SU(2), and SU(3) are the foundations that must be mastered.
SU(1), SU(2), and SU(3) are all Lie groups from a mathematical point of view. From a physical point of view, they apply a transformation to the system so that the system has some invariance under this transformation. .
Mathematically, these three groups are their own geometric structures as Lie groups. It can be imagined that they are all smooth geometries with their own dimensions.
From a mathematical point of view, this dimension is the dimension of the tangent space and can be calculated specifically. For example, SU(2) is 3-dimensional and SU(3) is 8-dimensional.
This dimension has a very clear physical meaning, which is the dimension of the mediator in the interaction, or the type of mediator.
For example, the only kind of mediator of electromagnetic interaction is photon, so its corresponding gauge field is U(1).
There are three types of weakly interacting mediators: W+, W-, and Z, so it can be inferred that the gauge field it corresponds to is SU(2), because SU(2) is three-dimensional.
That is.
The electromagnetic force corresponds to the U(1) group, the weak interaction force corresponds to the SU(2) group, and the strong interaction force corresponds to the SU(3) group.
In the SU(3) group, there is another 8-dimensional representation, that is, eight generators.
Therefore, the eight-fold method means that every 8 particles with similar properties can be filled in the 8-dimensional representation of the SU(3) group. It divides strongly interacting elementary particles with similar properties into a family, and considers that each family member should have 8.
The meson octet and baryon octet in particle physics are all within the scope of the octet, and later expanded to the tenth state.
So the X sub-X double state you see is essentially a derivative of the eight-fold method.
Of course.
At this time, the Eightfold Method is still very controversial, so experts soon put forward different opinions:
"SU3 group? Comrade Hong Yuan, according to you, the so-called Yuanhadrons are not one or two, but eight?"
"If there are so many so-called metahadrons, how can we solve the CP violation property? - The simplest question. In this situation, wouldn't the core of homomorphic mapping have to be two to one in mathematics? ”
The scholar who spoke was called Wang Zhuxi. He was also a well-known physicist in China and one of the first members of the academic department in China.
However, Wang Zhuxi's previous work was mainly in education, and his interaction with Zhu Hongyuan was not that deep.
Hearing Wang Zhuxi's question, Zhu Hongyuan smiled slightly:
"Comrade Zhuxi, I can answer your question."
I saw him picking up paper and pen from the table beside him, and quickly wrote on the table while explaining:
"Comrade Zhuxi, the essence of homomorphic mapping is actually the mapping verification of unitary matrices. As long as it can be proved that the elements of the SO(3) group can be mapped to the 2X2 matrix D1/2(α, βγ) with determinant 1, then That’s it.”
"According to the definitions of SU(2) group and SO(3) group, SO(3):={O∈GL(3, R)|OTO=13, det(O)=1}, SU(2):= {U∈GL(2,C)|UU=12, det(U)=1}. ”
"Then find a three-dimensional vector vv=(v1, v2, v3), and you can use the Pauli matrix to map it into a 2×2 unscented Hermitian matrix, that is, vv→rr=viσi=(v3v1iv2v1+iv2v3). This mapping The inverse mapping is vi=12tr[σirr], and there are det(rr)=|vv|2, and 12tr(rr2)=|vv|2”
"This unsigned Hermitian matrix can represent the algebra on the SU(2) group, then the adjoint effect of the SU(2) group on this algebra is rr=urru. where u∈SU(2)"
"Then a representation in the three-dimensional real vector space is induced, v′i=12tr(σirr′)=12tr(σiuσju)vj, v′i=Rji(u)vj, therefore, Rji(u)=12tr(σiuσju) ”
"In this case, we only need to prove that R(u)∈SO(3), our idea is."
Looking at Zhu Hongyuan who was writing so eloquently, Xu Yun couldn't help but reveal a hint of subtlety on his face.
Is this a coincidence?
To know.
In later generations of Chinese quantum field theory, the main "operator" of the proof of group theory in homomorphic mapping was none other than Zhu Hongyuan
However, Zhu Hongyuan compiled that set of books in the mid-1980s. Now it seems obvious that this is another achievement that was buried due to the international blockade.
More than ten minutes later.
Under the gaze of everyone, Zhu Hongyuan wrote the last paragraph:
"According to the definition of kernel space, the kernel of this homomorphic mapping is H={u∈SU(2)|R(u)=13}. Therefore, urru=rr is required, which is true for any rr."
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"According to Schur's lemma, u=λ12, where λ is a constant, and because det(u)=1, so λ=±1. Since R(u)=R(u), and the core of this mapping is { 12, 12}, it can be proved that this homomorphic mapping is mathematically two to one. ”
"."
Looking at the calculation results in front of him, Wang Zhuxi also fell into silence.
Zhu Hongyuan actually deduced it?
And looking at this situation, it seems that he had a specific calculation idea a long time ago?
However, after being quiet for half a minute, Wang Zhuxi couldn't help but touched his chin and said:
"Comrade Hong Yuan, I don't mean to be arrogant. It's just that we are engaged in physics research. It seems that it is not enough to simply deduce the truth from mathematical results, right?"
"If there are no clearer experimental results, I will still maintain my opinion on your meta-hadron model."
Hearing this, Zhu Hongyuan also showed some embarrassment on his face.
He naturally knew that Wang Zhuxi was not targeting him. After all, mathematics and physics were indeed two subjects.
Although there is a saying that everything is number, the essence of this is that it is logically self-consistent, but mathematics is also logically self-consistent.
At least for now, Zhu Hongyuan does not have enough evidence to support his theory.
However, there was a moment of silence at the scene.
A voice suddenly sounded from a table not far away from the crowd:
"Ah, it's so strange." Note:
I was coding in an Internet cafe late at night, and the big guy next door took off his shoes and socks and kept his feet bare (it didn’t smell like anything and he didn’t raise it to the table). I hesitated for a while but didn’t do it because of my personal image
(End of chapter)