Great Country Academician

"Little brother, this experiment is over, why are you still analyzing the data?"

At the desk, Xu Chuan raised his head when he heard the voice, and saw Senior Brother Qi Xishaoqi standing aside.

"Brother Qi."

Xu Chuan said hello, and then said: "No, the arrangement on the tutor's side has been completed, and I am tossing about my own things here, not looking for Tang Chuan coupling data."

Hearing this, Qi Xishao was stunned for a moment, and asked curiously, "Huh? Then what are you analyzing?"

He thought that Xu Chuan was trying to continue to search for traces of the coupling between Higgs and Yu Chuan, the third-generation heavy quark, but he didn't expect it to be so.

"Do an analysis and see if you can deduce from these data the ideal search channel for the Higgs boson's most likely decay."

Xu Chuan said casually, and his eyes fell on the Dalitz picture again.

Perhaps he should change his thinking, analyze from the angle of his original habits, and then use mathematical methods to verify, so that he may be able to find something.

He is not a very stubborn person. When one method fails to work, letting go of it for a short time and starting from another method or angle can sometimes have a completely different effect.

To engage in scientific research and academics requires the spirit of digging into the horns, but practical actions cannot be trickling into the horns.

"Finding the ideal search channel for the most likely decay of the Higgs boson?"

Qi Xishao looked at Xu Chuan with a strange expression, and continued, "Are you referring to the Yuchuan coupling level between Higgs and the third-generation heavy quark?"

"If this is the case, it has been predicted in the standard model. In experiments below the collision energy level of 13Tev, it will be about 34fb~56fb at the proton-proton center of mass energy, and the final state of llbb decay is in transverse dynamic equilibrium. The system makes a restrictive fit of "

"You should know these things, right?"

Qi Xishao looked at Xu Chuan, and briefly stated the Standard Model's prediction of the Higgs particle's decay.

As a physics researcher, and also a particle physics researcher, there's no reason why I don't know this.

Xu Chuan stared at the Dalitz diagram and said without turning his head: "I know these things, but from the prediction of the standard model, the range of its prediction is a bit large. I wonder if I can narrow these things down."

"In this way, it will be more efficient to find the Yuchuan coupling between Higgs and the third-generation heavy quark. If we can lock the most ideal search decay channel, then we will be able to find it in the next collision experiment."

Hearing this, Qi Xishao shook his head and persuaded: "Then it's up to you, but I suggest you give up."

"It's not like no one has done this work before, but no one has ever been able to shrink the predictions of the Standard Model. It's just too hard."

"Moreover, even if you make it, you won't get any big rewards. At most, it will shorten the time for the discovery of the Yukawa coupling phenomenon between Higgs and the third-generation heavy quark."

"Although this may save CERN millions or tens of millions of meters of gold in collision funds, CERN will not give you a special award for this."

After knowing that Xu Chuan was not continuing to study the data on the coupling between Higgs and Tang Chuan, the third-generation heavy quark, Qi Xishao let go of his worries.

However, he is not optimistic about Xu Chuan's attempt to lock the most ideal search decay channel for the coupling of the Higgs and the third-generation heavy quark Yu Chuan.

As he said before, this job is too difficult.

CERN has also studied this aspect before. After all, this can save a lot of money, but no one has ever been able to do it.

But as long as this little junior doesn't get into a corner and falls into a state of being hit, other things don't matter.

If he wants to study, he can study it. Anyway, if there is no result in the end, he will naturally give up.

Qi Xishao left, but Xu Chuan didn't care, his attention was still on the Daritz map in front of him.

After contemplating for a while, he picked up the ballpoint pen from the table and started to work on the manuscript paper laid out.

In a while, it will be difficult to sort out these things from a mathematical point of view, but he can sort out these things from a physical point of view first.

[The fitted value VHbb of the Higgs boson signal intensity parameter μ is for mH=125 GeV, which is applicable to the WH and ZH processes and their combinations. The value of the individual μVHbb(W/Z)H process is independently floated by simultaneous fitting The signal intensities of the WH and ZH processes are obtained, from which the compatibility of the respective signal intensities can be calculated to be 84%. 】

【.】

[Impact of systematic uncertainty in the fitted Higgs boson signal intensity parameter μ for nominal MVA analysis of 13 TeV data. System uncertainties are listed in descending order of their effect on μ. Boxes represent changes in μ; refer to the top x-axis when the corresponding individual disturbance parameter θ is fixed to]

[Expected and observed significance values ​​(standard deviations) for independent fits of the H→bb channel and their combinations using 7 TeV, 8 TeV and 13 TeV datasets]

It took two days for Xu Chuan to sort out the Dali Zitu in his opponent's hand.

The Dalitz diagrams and corresponding information are stored in the computer and projected on the display screen.

Xu Chuan flipped through them methodically.

"Overview of systematic uncertainties in .diboson production background modeling. PS/UE denotes partial subshower/potential event. S notation is used when evaluating shape uncertainty only."

"When determining the signal intensity produced by the (W/Z)Z double boson, the normalization uncertainty is removed because the normalization is unconstrained. If it is accepted that the magnitude of the systematic uncertainty varies from region to region, then Show a range."

"If this range can be determined, it may be possible to find the fitted value H→bb of the Higgs boson signal intensity parameter μ, and the analysis data of VH, ttH and ggF+VBF used in run 1 and run 2 respectively, and combinations of them."

"If this step can be achieved, at least the ideal search decay channel for the coupling between Higgs and the third-generation heavy quark Yukawa can be narrowed down to a large extent."

"But how should I do it?"

Staring at the information on the screen, Xu Chuan fell into deep thought again.

From the point of view of particle physics, he has made sure that there is indeed a range, which can be used to find the fitted value H→bb of the signal intensity parameter μ of the Higgs boson.

But how to calculate this range mathematically, he still has no clue.

Of course, this is normal.

If it were really that easy to do, this work would have been done long ago.

For physicists at CERN, rather than studying how to narrow down the optimal search decay channel, it is better to optimize the calculation method.

Efficient calculation methods can eliminate complex QCD background interference and obtain relatively pure signals, thereby increasing the probability of finding useful signals.

As for how to narrow down the optimal search decay channel? It would be easier to find a way to ask the member states for more money and conduct more collision experiments.

Staring at the information on the monitor, Xu Chuan pinched the bridge of his nose, got up and left the office.

If you can't find inspiration squatting in the office, it's better to go out for a walk to relax.

"It's strange, you actually came out of the office."

On the lawn outside the CERN work area, Xu Chuan was sitting on a long wooden chair, and a surprised voice came from his ear.

Turning his head to look, it was Qi Xishao, Senior Brother Qi, who came over with a plastic bag in his hand, sat down on the bench, took out a bag of snacks from the bag and handed it to Xu Chuan.

Xu Chuan took it and took a look. It was a bag of spicy 'Jinzai Xiaoyu'.

"Where did you buy this thing?" Xu Chuan asked curiously. It was obviously a domestic product, and there is no Chinatown in Geneva.

"Drove to Zurich to buy it."

Qi Xishao lay lazily on the bench, opened a bag of snacks and basked in the sun while eating.

"So? You drove several hours to Zurich just for a few bags of snacks?" Xu Chuan stared at the plastic on the bench, feeling a little silly.

Qi Xishao shrugged: "That's all I have as a hobby. I might not be able to go back to China twice a year. It's not bad to be able to eat the food from my hometown."

"By the way, how is your research going?"

Xu Chuan disassembled Jinzai Xiaoyu, took a bite, and replied: "There is not much progress, and I have encountered some troubles."

"Normally, the thing you're studying is extremely difficult. Not only does it require a deep knowledge of physics, it also requires a strong mathematical ability. There are not many people in the entire particle physics world who have the ability to study this thing."

Qi Xishao was clear about this result, without any surprises.

"Instead of studying this, to be honest, you might as well study the calculation method. At least this is much easier, and an excellent calculation method can eliminate the scattering background and calculation interference, which can greatly increase the probability of finding useful information."

"As for finding the Yukawa coupling level between the Higgs and the third-generation heavy quark, just leave it to the collider under our feet."

"As long as it is activated enough times, it will be found one day."

Xu Chuan smiled and said, "Maybe, but I still want to try."

Seeing that Xu Chuan still didn't want to give up, Qi Xishao shook his head slightly and said, "Then I suggest you find your mentor, Edward Witten."

"If there is anyone who can help you in this regard, it may be him."

Hearing this, Xu Chuan's eyes suddenly lit up.

Perhaps there was someone who could indeed help him in this regard.

Of course, this person is not Edward Witten. Witten specializes in quantum field theory, string theory and related topology and geometry, but the research on particle physics is not so deep.

However, there is a person related to Weiteng who has done a lot of research in this area.

That is Edward Witten's mentor, or his master, David Gross.

David Gross is now the chairman of the CERN Council and one of the founders of quantum chromodynamics, particle physics and string theory.

He has conducted in-depth research in gauge field theory, particle physics and superstring theory.

In 2004, he won the Nobel Prize in Physics for his discovery of the "asymptotic free phenomenon of quarks", and he belongs to the top of the physics world.

According to statistics, he is now an academician of at least ten countries, including Hua Guo, who was elected as a foreign academician of the Hua Guo Academy of Sciences in 2011.

It can be seen how awesome this person is.

But now he is not very familiar with David Gross, and the best way to ask him for help is through his mentor Edward Witten.

After throwing a "thank you" to Senior Brother Qi, Xu Chuan ate up the Jinzai Xiaoyu in two bites, then returned to his hotel room, and sent an email to Edward Witten, who had returned to the Institute for Advanced Study in Princeton, requesting He helped introduce David Gross.

Maybe Professor Witten is in front of the computer? It might also be that his email was set as a follow, anyway, this time, he didn't have to wait long before he received a reply.

"I have already contacted Professor Gross, he will be waiting for you in his office at two o'clock tomorrow afternoon, but you don't have much time, only one hour."

"You can sort out the questions you need to consult first, and send them to him by email first, so as to avoid wasting time. Professor Gross's email address is *****."

Regarding Xu Chuan's request, Professor Witten contacted David Gross for him without any delay after receiving the email.

Of course, this is nothing.

After all, in name, David Gross is Xu Chuan's patriarch.

"Thank you tutor, I will sort out the problem first."

After receiving Weiteng's reply, Xu Chuan quickly sorted out his research and data analysis results these days, and then packed and compressed them into a file and sent it to Professor David Gross.

The next day, at two o'clock in the afternoon, Xu Chuan came to CERN's nuclear research center building.

As the chairman of the CERN Council, David Gross basically works here throughout the year.

According to the location in memory, Xu Chuan successfully found the office of David Gross.

Knocking on the wooden door, a voice came from inside immediately.

"Please come in."

Xu Chuan pushed open the door and walked in. In the office, an old man wearing rimless glasses was looking at him with a smile.

"Welcome to come. The report you chaired in the first two months will be very exciting."

While talking, David Gross got up with a smile, made a cup of tea for Xu Chuan, and said, "I heard that people in Huaguo drink tea, and I happen to have some tea leaves from others."

"Thank you." Xu Chuan quickly took the teacup with both hands.

After making a cup of tea for Xu Chuan and another cup of coffee for himself, David Gross looked at Xu Chuan and said slowly:

"Sit down, I don't have much time, and there will be a meeting later."

"I have read the email you sent me last night. I have to say that your idea is very unique. It may be difficult to achieve it. But I have some ideas here. Maybe you can refer to it."

Seeing that he was getting to the point, Xu Chuan also became serious and listened carefully.

After chatting for a while, David Gross looked at Xu Chuan and said, "I don't know how to use mathematics to narrow down the optimal search decay channel for the coupling between Higgs and the third-generation heavy quark Yu Chuan." Do."

"But from the perspective of particle physics, all particles are made of quarks. Maybe you can try to study them from the two aspects of 'quark asymptotic freedom phenomenon' and 'quark confinement'?"

Should we start with the study of 'Asymptotic Freedom of Quarks' and 'Quark Confinement'?

Hearing the old man's words, Xu Chuan fell into deep thought.