"Junior brother, this experiment is over, why are you still analyzing the data?"
In front of the desk, Xu Chuan raised his head when he heard the voice and saw Senior Brother Qi Xishao standing aside.
"Senior Brother Qi."
Xu Chuan said hello and then said: "No, the instructor's arrangements have been completed. I am working on my own stuff here, not looking for Yukawa coupling data."
Hearing this, Qi Xishao was stunned for a moment, and asked curiously: "Huh? Then what are you analyzing."
He thought Xu Chuan was trying to continue looking for traces of Yukawa's coupling between Higgs and the third-generation heavy quark, but he didn't expect it to be the case.
"Do an analysis to see if we can deduce from these data the ideal search channel for the most likely decay of the Higgs boson."
Xu Chuan said casually, his eyes falling on the dalitz picture again.
Maybe he should change his thinking, first analyze it from the perspective of his original habits, and then use mathematical methods to verify it, so that he might be able to find something.
He is not a very stubborn person. When one method doesn't work, temporarily giving up and starting from another method or angle can sometimes have completely different results.
Engaging in scientific research and academic pursuits requires a sharp-edged spirit, but actual actions cannot be sharp-edged.
"An ideal search channel for the most likely decay of the Higgs boson?"
Qi Xishao looked at Xu Chuan with a strange expression, and then said: "Are you referring to the Yukawa coupling energy 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 llbb decay final state will have a transverse dynamic equilibrium
The system makes a restrictive fit as..."
"You should know these things, right?"
Qi Xishao looked at Xu Chuan and briefly explained the Standard Model's prediction of the decay of the Higgs particle.
As a physics researcher, and also a researcher of particle physics, there is no reason why I don’t know this.
Xu Chuan stared at the dalitz diagram and said without looking back: "I know this, but judging from the predictions of the standard model, its prediction range is a bit large. I am wondering if I can narrow these things down."
"This way, it will be more efficient to find the Yukawa coupling between Higgs and the third-generation heavy quark. If we can lock the optimal search decay channel, then we can find it in the next collision experiment."
Hearing this, Qi Xishao shook his head and advised: "That's up to you, but I suggest you give up."
"This work has not been done before, but no one has ever been able to shrink the predictions of the Standard Model. It is too difficult."
"Moreover, even if you make it, you won't get any big reward. At most, it will shorten the time for the discovery of the Yukawa coupling phenomenon between Higgs and third-generation heavy quarks."
"Although this may save millions or tens of millions of dollars in collision funds, it will not give you a special award for it."
After knowing that Xu Chuan was not continuing to study the Yukawa coupling data between Higgs and third-generation heavy quarks, Qi Xishao was relieved of his worries.
However, he is not optimistic about Xu Chuan's attempt to lock in the optimal search decay channel for the Yukawa coupling of Higgs and third-generation heavy quarks.
As he said before, this job is too difficult.
This aspect has been studied before. After all, it can save a lot of money, but no one has ever been able to do it.
But as long as this junior fellow student doesn't get into trouble and fall into a state of being attacked, other things don't matter.
If he wants to study, he can study it. In the end, he will naturally give up if there is no result.
...
Qi Xishao left, and Xu Chuan didn't care. His attention was still on the Daliz picture in front of him.
After pondering for a while, he picked up the ballpoint pen from the table, laid out the manuscript paper, and started working.
For a while, it was difficult to clarify these things from a mathematical perspective, but he could sort them out from a physical perspective first.
[The fitted value vhbb of the Higgs boson signal intensity parameter μ is for mh=125 gev, applicable to wh and zh processes and their combinations... The value of the individual μvhbb(w/z)h process is obtained by
It is obtained by simultaneously fitting the signal strengths of the independently floating wh and zh processes. From this, it can be calculated that the compatibility of each signal strength is 84%.】
【......】
[Effects of systematic uncertainties in the fitted Higgs boson signal intensity parameter μ applied to nominal mva analysis of 13 tev data. System uncertainties are arranged in descending order of their effect on μ. Boxes represent μ
Change; refer to the top x-axis, when the corresponding individual interference parameter θ is fixed to...]
[Expected and observed significance values (standard deviation) of h→bb channels and their combinations independently fitted using 7 tev, 8 tev and 13 tev data sets...]
After spending two days, Xu Chuan completed sorting out the Daliz pictures in his hands.
The dalitz pictures and corresponding information are saved in the computer and displayed on the display screen.
Xu Chuan read through it in an orderly manner.
"....An overview of systemic uncertainties in modeling diboson production backgrounds. ps/ue stands for parton shower/potential event. When only shape uncertainty is evaluated, the s notation is used."
"When determining the (w/z)z double boson production signal intensity, since the normalization is unconstrained, the normalization uncertainty is eliminated. If it is accepted that the magnitude of the system 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, as well as the vh, tth and ggf vbf analysis data for run 1 and run 2 respectively, and
A combination of them.”
This chapter is not finished yet, please click on the next page to continue reading the exciting content! "If we can achieve this step, we can at least reduce the ideal Yukawa coupling between Higgs and the third-generation heavy quark to a great extent.
Searching for decay channels."
"But, how should I do it?"
Staring at the information on the display screen, Xu Chuan fell into deep thought again.
From the perspective of particle physics, he has determined that there is indeed a range that can be used to find the fitting value h→ bb of the Higgs boson signal intensity parameter μ.
But he still had no idea how to calculate this range mathematically.
Of course, this is normal.
If it were that easy to do, this work would have been done long ago.
For physicists, instead of 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, thus increasing the probability of finding useful signals.
As for studying how to narrow down the optimal search decay channel? It would be easier to find ways to ask each member state for more money and conduct more collision experiments.
........
Staring at the information on the screen, Xu Chuan pinched the bridge of his nose, stood up and left the office.
If you can't find inspiration while squatting in the office, you might as well go for a walk and relax.
"It's strange that you actually came out of the office."
On the lawn outside the work area, Xu Chuan was sitting on a long wooden chair, and a surprised voice came to his ears.
Turning around, he saw that it was Senior Brother Qi Xishao 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 saw a bag of spicy 'Jinzi Xiaoyu'.
"Where did you buy this?" Xu Chuan asked curiously. This is obviously made in China, and there is no Chinatown in Geneva.
"Drove to Zurich to buy it."
Qi Xishao lay lazily on the bench and opened a bag of snacks while eating and basking in the sun.
"So? You drove several hours to Zurich just for a few bags of snacks?" Xu Chuan stared at the plastic on the bench and felt a little stupid.
Qi Xishao shrugged: "This is my only hobby. I may not be able to go back to the country twice a year. It's not bad to be able to eat food from my hometown."
"By the way, how's your research going?"
Xu Chuan opened the Jinzi fish, took a bite, and replied: "There is not much progress, we encountered some troubles."
"Normally, the thing you are studying is extremely difficult. It not only requires a deep foundation in physics, but also strong mathematical abilities. There are not many people who have the ability to study this thing. There are not many people in the entire particle physics community."
Qi Xishao was fully aware of this result and was not surprised at all.
"Instead of studying this, to be honest, you might as well study the calculation method. At least this is much easier, and excellent calculation methods can eliminate scattering background and calculation interference, which can greatly increase the probability of finding useful information."
"As for the search for the Yukawa coupling level between Higgs and third-generation heavy quarks, just leave it to the collider at our feet."
"As long as it is started 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 go find your mentor, Edward Witten."
"If there is anyone who can help you in this regard, it might be him."
Hearing this, Xu Chuan's eyes suddenly lit up.
Maybe there is someone who can really 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 his research on particle physics is not that in-depth.
However, there is someone related to Witten who has done very good research in this area.
That is Edward Witten’s mentor, or his master, David Gross.
David Gross, now chairman of the board, is 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 freedom phenomenon of quarks', making him one of the top names in physics.
According to statistics, he is now an academician of at least ten countries, including China. In 2011, he was elected as a foreign academician of the Chinese Academy of Sciences.
This shows how awesome this guy is.
However, he is not very familiar with David Gross now, so 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 finished the Jinzi Xiaoyu in his hands, 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 was in front of the computer? Or maybe his email was set to follow. Anyway, this time, he didn't 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 via email first, so as to avoid wasting time. Professor Gross's email address is *******."
Regarding Xu Chuan's request, Professor Witten did not delay at all and contacted David Gross on his behalf after receiving the email.
Of course, this is nothing.
After all, David Gross is still Xu Chuan’s ancestor in name only.
"Thank you, tutor, I will sort out the problems first."
After receiving Witten's reply, Xu Chuan quickly sorted out his research and data analysis results these days, then packaged and compressed them into files and sent them to Professor David Gross.
...
The next day, at two o'clock in the afternoon, Xu Chuan arrived at the Nuclear Research Center building.
As the chairman of the board of directors, David Gross works here basically all year round.
According to the location in his memory, Xu Chuan successfully found David Gross's office.
After knocking on the wooden door, a voice immediately came from inside.
"Please come in."
Xu Chuan opened the door and walked in. In the office, an old man wearing rimless glasses was looking at him with a smile.
"Welcome to your arrival. The reports you will host in the first two months will be quite exciting."
While talking, David Gross stood up with a smile, made a cup of tea for Xu Chuan, and said, "I heard that Chinese people all drink tea, and I happen to have some tea here given by others."
"Thank you." Xu Chuan quickly took the tea cup with both hands.
After making a cup of tea for Xu Chuan and a cup of coffee for himself, David Gross looked at Xu Chuan and slowly said:
"Sit down, I don't have much time. I have a meeting later."
"I have read the email you sent me last night. I have to say that your idea is very unique and it may be difficult to implement it. However, I have some ideas here. Maybe you can refer to it...
."
Seeing that the topic was entering, Xu Chuan also became serious and listened attentively.
After chatting for a while, David Gross looked at Xu Chuan and said: "How to use mathematics to narrow down the optimal search decay channel for the Yukawa coupling of the Higgs and the third-generation heavy quark? I don't know how.
Do."
"But from the perspective of particle physics, all particles are composed of quarks. Maybe you can try to study them from the two aspects of quarks' asymptotic freedom phenomenon and 'quark confinement'?"
Start studying the phenomenon of asymptotic freedom of quarks and ‘quark confinement’?
Hearing the old man's words, Xu Chuan fell into deep thought.