Time passed quietly.
Soon, the news that Xiao Yi was going to hold a report spread among Institute of High Energy Physics. After all, it was the director Tang Yifang who arranged the matter, so the news spread relatively quickly.
Various discussions immediately occurred inside Institute of High Energy Physics.
"Xiao Yi actually came to our research institute to give a report?"
"Xiao Yi actually came to our research institute?"
"Xiao Yi... Who is it?"
"The village hasn't been connected to the internet yet."
"It was arranged by Director Tang, and the director requested that all researchers in the institute and Associate Researcher should temporarily put aside their work to participate. As for others, it is recommended to participate."
"Ah? Why? Is his report so important that so many of us have to go?"
"Who knows? Didn't he study mathematics? Now he has made achievements in our high-energy physics?"
"Ahem, after all, our high-energy physics and mathematical physics are closely related. Maybe they really have something important?"
"But then again, what is the theme of his report called?"
"It seems to be called... well, it feels a bit strange. It's called: Experimental Error Analysis and Data Processing?"
"What is it? Error analysis... and data processing? In other words, it has a lot to do with mathematics?"
"Hiss... it seems to be true?"
"Ah!!! Why mathematics!"
For a time, many people showed pain.
Although experimental error analysis and data processing are very important in their field, the accuracy of many results is related to this.
However, it is too painful for them to learn this kind of thing!
However, there is no way, the director has made a request, and researchers like them or Associate Researcher have to participate, so what else can be done?
We can only wait for the report day to arrive.
The time came to the day before the report.
On this day, two banners were posted at the door of Institute of High Energy Physics, one in Chinese and one in English.
The above all means: [Welcome Professor George Parisi and his team from CERN to visit Institute of High Energy Physics for exchange and learning!]
At ten o'clock in the morning, a bus stopped at the entrance of the institute. As the door opened, foreign faces got off one after another.
The leader was an old professor who looked very Italian.
This is George Parisi, the giant of Theoretical physics community and the candidate of Nobel Prize in Physics. At the same time, he has won almost all other awards in physics. Just in the first half of this year, he also won the Wolf Prize in Physics, which is second only to the Nobel Prize in gold content.
According to some situations in previous years, the Wolf Prize is the benchmark for the Nobel Prize. Maybe in October this year, he will become the Nobel Prize in Physics winner.
It can be said that it is a very rare thing to be able to invite him to Institute of High Energy Physics for exchange and learning.
In front of the car door, Tang Yifang and all the leaders of Institute of High Energy Physics were already standing here waiting. When they saw the big boss coming down, they all went up to greet him.
"Professor Parisi, welcome!"
Tang Yifang stepped forward and shook hands with George Parisi.
George Parisi nodded. "Hello, Professor Tang, I am very happy to come to China Institute of High Energy Physics to communicate with you."
While chatting, they introduced each other to each other, and finally, everyone from CERN was welcomed into the institute.
Tang Yifang began to explain some of the next exchange arrangements with George Parisi: """Today I will mainly introduce you to some of the internals of our Institute of Physics, and then there is BEPC, and then..."
Before he could say what was coming next, George Parisi interrupted him and said, "There's no need to say too much about this. Your BEPC collision energy is too low, and you can't do any high-energy experiments."
"I'm more interested in what you told me about tomorrow's report yesterday."
George Parisi asked, "That mathematical genius Xiao Yi, tomorrow's report may involve a very important discovery?"
Tang Yifang was stunned for a moment, thinking that this was the matter that concerned him the most.
Then he smiled and nodded and said, "Yes, Professor Parisi, you should also know that Xiao Yi is a mathematical genius, so he provided a brand-new error analysis and processing method for the experimental errors of our particle collisions."
"According to his new method, after processing a type of data, he discovered something that was inconsistent with the current theoretical data."
George Parisi was immediately surprised. "It's not consistent with the current theoretical data? Is this sure?"
Tang Yifang nodded and said, "According to Xiao Yi's calculation results, that's it."
George Parisi couldn't help but think.
If this is true, this is a very significant discovery.
After a moment, he asked, "When will the report be tomorrow?"
Tang Yifang laughed when he heard him ask this. Obviously, the other party was interested.
"Ten o'clock tomorrow morning."
"Okay! Then I'm looking forward to the report meeting tomorrow." Parisi said, "But, which theoretical data are inconsistent with the data you mentioned?"
Tang Yifang smiled apologetically, "Well... let me give it a try first. You will know when I report tomorrow."
"Oh?" George Parisi raised his eyebrows, and then said with a smile, "Okay."
The arrival of George Parisi and his team immediately made Institute of High Energy Physics lively, but it did not have much impact on Xiao Yi.
There was less than a day left before the start of the report, and during these days, in addition to further optimizing the error analysis and processing methods, he also used the optimized method to process more experimental data.
Nearly two thousand pieces of data have been processed.
And all these data show that W boson is indeed very likely to be overweight. The standard deviation difference basically reaches at least 5σ, or even more than 5σ, and quite a few exceed 6 to 7σ, or even more.
Of course, the amount of data for 2000 is still relatively small, but it is enough to make the physics community begin to doubt W boson mass in Standard Model.
"Just waiting for tomorrow's report."
According to the data calculated on the scratch paper, Xiao Yi smiled slightly and then put the papers away.
At this time, from the corner of his eye, he caught sight of several other pieces of draft paper next to the corner of the table.
Take these scratch papers, and there are a lot of physical derivation formulas written on them that look dizzying.
[L_YM=1/4FμνaFaμν...]
[Fμνa=μAνaνAμa+gf^abcAμbAνc...]
These things are all related to the Yang-Mills equation.
These days, he has also begun to study the quality gap issue.
Although the existence of the mass gap has been verified in many experiments, it has not been proved mathematically.
Only by proving it mathematically can we help physicists understand the strong interaction more deeply and ensure the internal consistency and rigor of non-Abelian gauge theories. This will provide a solid theoretical foundation for the academic community, so that internal contradictions and inconsistencies can be avoided when unifying different interaction forces at a higher level.
In particular, Grand Unified Theory attempts to unify the strong and electroweak interactions into a single gauge group at high energy scales.
Therefore, it is obvious that once the mass gap problem is proven, it will indirectly help to unify the three fundamental forces, strong, electroweak and weak.
"Well... how should we prove this?"
Looking at this question, Xiao Yi's mind fell into deep thought.
Facing this kind of physical mathematical proof, he, who had been studying pure mathematical problems before, felt a little uncomfortable.
However, this problem is not big. After all, various mathematical methods still need to be followed.
In this way, time passed slowly, and many thoughts came to Xiao Yi's mind.
However, there is still a long way to go to solve this problem.
Just like that, one day passed again.
The next day, 10 am.
High Energy Physics Research Institute, the largest lecture hall is almost full of people.
All the researchers from Institute of High Energy Physics and Associate Researcher are already there, and there are also some Assistant Researcher and Intern Researcher who came to participate because of interest. Of course, there are also other postdocs, graduate students, etc., a total of more than 150 people.
In addition to these Institute of High Energy Physics researchers, there is also the team of Professor George Parisi from CERN.
At this time, Professor George Parisi and Director Tang Yifang were sitting in the middle of the first row. On the seat next to them, Xiao Yi was communicating with Professor Parisi because the report had not officially started yet.
"I heard Professor Tang say that your research results can find a result that is inconsistent with the prediction of Standard Model, right?"
Parisi asked with a smile.
Xiao Yi nodded. "Yes, according to my calculations..."
But before he could finish speaking, Parisi reached out to stop him. "Okay, let's talk about this later when you report."
He glanced at Tang Yifang next to him with a smile, and said, "After all, yesterday, Professor Tang asked me to know from your speech in today's report, so there is no need to rush to say it now."
"Professor Tang, do you think so?"
Tang Yifang laughed, "Since Professor Parisi thinks so, then naturally we can't let you down. Xiao Yi, it will be up to you later."
"Of course no problem."
Xiao Yi smiled and nodded.
At this time, the time for the speech had officially arrived. He stopped talking nonsense and walked directly to the stage.
The lecture hall quickly fell silent.
Standing on the podium facing so many physicists present, Xiao Yi bowed lightly, and then said with a smile, "Hello everyone, I am very happy to be able to share my recent results with you here at Institute of High Energy Physics."
"First of all, I would like to thank Director Tang for arranging such a report for me. At the same time, I would also like to thank Professor Parisi for being willing to attend my report."
"Honestly, although I have done a lot of reports, this is my first time doing a physics report, so please forgive me if there are any shortcomings later."
"Well, without further ado, let's get to the point."
Xiao Yi Click on the multimedia, the PPT lights up, and the theme of this report also appears on the screen.
[Experimental error analysis and data processing]
"For any experiment, limited by technical means, various errors will inevitably occur when measuring data, and these errors will greatly affect our judgment of the results."
"This is especially true for high-energy physics. After all, what we are observing is particle collisions with speeds reaching 99.99...% of the speed of light, and the events that occur may even disappear in just a few microseconds, so the final data becomes even more inaccurate."
"In this regard, we have to use more advanced error analysis methods to help us analyze which part of an experimental data is error and which part is real, and then use data processing methods to retain the real data."
Xiao Yi smiled, "It is said that the relationship between mathematics and physics is close, and I think it can be proved from this point."
The people present laughed.
"What I bring to you in this report is a more sophisticated error analysis and processing method, which can help us further extract effective information from the data."
"Next, I will directly use a set of experimental data as an example."
As soon as the PPT moved, a set of data appeared on it.
"This is a set of signal data about the lepton decay mode of W boson."
"We all know that W boson can decay into a lepton and a neutrino, where the lepton can be an electron, a muon, or a tauon."
While talking, Xiao Yi also came to the blackboard next to him and wrote on it: [W±→±+ν].
"The set of data I chose is the combination of W boson decaying into high-energy electrons and neutrinos. The electrons are detected by the electromagnetic calorimeter in the detector. The electron energy given here is 45.38GeV."
"Since neutrinos will not be directly detected, their existence is manifested by the missing transverse momentum. The missing transverse momentum we obtained here is 35.31 GeV."
"Okay, now, we use traditional methods to analyze and process the error."
"First consider the energy resolution error of the detector and calculate the measurement error of electron momentum and MET..."
"Then we calculate it through the error propagation formula."
[σM=√￣[(MσE/E)^2+(MσMET/MET)^2]]
"Finally, we calculated the partial derivative and substituted the numerical value, and the final mass obtained was 80.319±0.044GeV. According to the calculation of Standard Model, W boson mass should be 80.379, and the error is within 2 standard deviations."
Xiao Yi turned his head, looked at the people present, and said, "Obviously, whether it is the 79.319 we calculated or the standard deviation of 0.044, the gap is really big. Of course, this may also be because the confidence level of a single data volume is too low."
"But now please let me continue to borrow this data and use my new method to analyze and process it."
"First, we need to recalibrate the detector data. Here, the method I use is Maximum Likelihood Estimation. Of course, if we just use Maximum Likelihood Estimation, there will definitely still be a gap. Then, I will need to introduce some new methods here..."
Xiao Yi raised the corners of his mouth slightly, turned around, and started writing on the blackboard.
As he demonstrated a few simple steps, Tang Yifang and Parisi both narrowed their eyes in the audience.
This mathematical method...
It seems a little different?
Xiao Yi actually introduced a new algorithm to optimize Maximum Likelihood Estimation!
Among the others, some more or less saw some of the mysteries and showed surprised expressions.
"... In this way, we calibrated the data of this detector, and the final data we obtained were: electron momentum 45.84GeV, missing transverse momentum 35.65GeV."
After getting this result, Xiao Yi did not stop and continued to the next step, "The next step is to analyze the error."
"The general use of the error propagation formula here will definitely not meet our requirements."
"Other existing systematic error analysis methods have limitations when dealing with complex data and cannot fully separate and quantify the impact of each error source."
"For this, we need to introduce an Error Matrix first."
error matrix.
In the audience, Tang Yifang heard Xiao Yi mention this, and quickly recalled the method Xiao Yi introduced to him ten days ago. It must be said that the error matrix is indeed a very subtle method.
Parisi, who was sitting next to him, didn't know when he took out the paper and pen, but started to calculate along with Xiao Yi.
Obviously he has been completely attracted by what Xiao Yi said.
At this time, when he heard the error matrix proposed by Xiao Yi, he raised his head and listened carefully.
In this way, time passed slowly, and Xiao Yi finally finished describing the error analysis framework.
"... At the end, we combine all the independent error components and then substitute them into such a new error propagation formula to calculate the overall systematic error."
"This new error propagation formula can help us divide the nonlinear relationships and interactions between various error sources in more detail."
"That way, we end up with cleaner data."
"Now, let's plug in the initial data..."
"The final result we can get is that the mass of W boson is 80.471±0.027GeV!"
Seeing this result, Parisi suddenly narrowed his eyes.
This result...
If you consider a range of 5 standard deviations, that's [80.336, 80.606].
Compared with the 80.379 predicted by Standard Model, this lower limit is already a bit dangerous!
This is almost a 4 standard deviation difference!
He suddenly realized why Xiao Yi was using W boson as an example.
Could it be...
"Of course, this result is relatively average."
"I don't see anything special. Probably the only thing worthy of attention is that the difference between it and W boson mass predicted by Standard Model is close to 4 standard deviations."
"But if we use this data method to process 2,000 sets of data, what will the final result be?"
Xiao Yi smiled slightly and revealed the answer.
As the pages on the PPT turned, finally, the results appeared.
[80.438±0.011GeV]
Just now, because Xiao Yi mentioned the standard deviation, when people off the court saw this result, they immediately calculated the five-standard deviation lower bound of this result.
80.383!
"What the hell?!"
"I bought it!"
Suddenly, the audience below all exclaimed.
"What is this?!"
"It means that the quality of W boson is higher than the predicted value of Standard Model?"
"This value really exceeds 5 standard deviations!"
"That's not true... it's just more than 4MeV, right?"
"Isn't this enough? Even if the lower realm only exceeds 4MeV, that's enough! Is this enough to publish a PRL?"
The entire lecture hall began to remember the various low voices of discussion, and the silence before turned into noisy.
How could they not be excited by a discovery beyond Standard Model?
This means new discoveries in physics!
But Xiao Yi did not stop them, after all, this was the effect he wanted.
At this time, Professor Parisi in the first row suddenly asked, "The amount of data you have is only 2,000?"
Xiao Yi nodded. "Yes, and these data are all derived from the results of a recent BEPC collision."
"The amount of data is still a bit small..." Parisi thought for a moment, and finally said, "I must say, your report did bring me a very big surprise."
"It's not just the problem of W boson being overweight. We all know that the quality of W boson was given by Higgs mechanism. So once the quality of W boson does not match the predicted value under Standard Model, it is very likely that there is a problem with Higgs mechanism, or it is imperfect."
"However, as I just said, the amount of data is still too small."
"If you can get results with a larger amount of data, I think that will help prove your results."
After listening to Parisi's words, Xiao Yi nodded.
At this time, Tang Yifang said, "Professor Parisi, we need your help. The data from the LHC may be able to help get a more accurate result."
"This..."
Parisi thought about it and finally said, "It's possible, but you also know that the recent data from the LHC will not be released in the first few years. Xiao Yi needs to come up with something that can convince CERN."
Then, he turned to look at Xiao Yi and said, "If you can write the contents of this report into a paper and publish it, I can convince CERN to provide this part of the data."
In response, Xiao Yi naturally nodded. "Of course, no problem."
"Okay." Parisi smiled and said, "Then I'll wait for you to finish the paper."