Chapter 169 An Overweight Particle?

"Strange?" Approaching, Senior Brother Yan stared at the computer screen for a while, his brows slightly frowned, "...it's really strange, isn't the experiment we conducted a collision in the 1-10GeV energy range? What about the data? Have you all gone to 1TeV?"

As he spoke, Senior Brother Yan cast a questioning look at Professor Greer.

The conversion between TeV and GeV is 1:1000, which is equivalent to the particle beam in the collider tunnel, and the energy of the collision has reached 1000GeV. As for the collision energy needed to find pentaquark particles, 6GeV is enough.

In order to find a particle located in the 6GeV energy region, the collision energy is set to more than 1000GeV. This is no longer a cannon hitting a mosquito, but a rocket hitting a fly.

However, upon hearing Yan Xinjue's question, Professor Greer laughed and explained in a nonchalant tone.

"As I said, the current state of the test track is not a formal experiment. As for why it is so big, you have to understand CERN's love for this new toy. If it is not for the limited budget of this experiment, they are even going to give it to You colleagues, show collisions above the 10TeV energy region."

To put it bluntly, it is to show off.

And it's Chi Guoguo's kind of showing off.

Imagine that theoretical physicists and high-energy physics laboratories all over the world are focusing on this place. If you don't take this opportunity to show off, wouldn't it be a waste of the billions spent on expanding the track?

If you don't let the collider spin the particle clusters inside, how can you let others know how awesome your machine is?

However, CERN does have the capital to show off. It is said that under extreme conditions, the expanded Hadron Collider can even perform 14TeV collision experiments. That is to say, each particle running in orbit will carry 7TeV of energy.

How terrifying is this energy?

In many cases, this energy unit (according to the mass-energy conversion formula) is also used to describe the mass of particles. For example, the mass of a hydrogen atom is about 1GeV, while the Higgs particle discovered in 2012 is 125GeV.

Comparing horizontally with peers, the limit of the Shangjing Electron Positron Collider is about 5GeV, which is an order of magnitude away from the energy unit of TeV.

If you want to catch up with this energy unit, you can only look forward to the completion of CEPC in Qindao, but that will be ten years later.

"...I don't mean that the energy section of the experiment is strange," Lu Zhou's finger almost touched the computer screen, "Didn't you notice it? There is an abnormal impact phenomenon here near 750GeV."

"It's not called a collision phenomenon, it's just a single two-photon signal, but it's a bit strange why it appears in the 750GeV energy region." Professor Greer touched his chin, "But it's strange, it's not uncommon for this to happen. , we can always observe some special signals on the ATLAS detector, but the data reflected in the statistical image may be just a 'noise'."

"Is this kind of situation very common?" Staring at the abnormal point on the screen, Lu Zhou couldn't help asking.

"It's quite common," Senior Brother Yan nodded, "We understand less than 1% of all the signals generated by proton beam collisions. So we usually speculate on conclusions and then verify them through experiments. If you stay here often will get used to it.”

High-energy physics itself is a very metaphysical thing.

Since the existence below the atomic level cannot be "directly observed", in order to determine the real existence of a particle, a very important indicator - confidence level will be involved.

This is a statistical concept.

In high-energy physics experiments, less than 3 times the standard deviation is called "sign", more than 3 times is called "evidence", and more than 5 times is called "discovery". Although words such as "breakthrough progress" and "significant discovery" often appear in the news, in fact, most cases are just "signs".

Based on this accepted theory, when the confidence level reaches 3sigma, it can barely be counted as a "sign".

A temporary characteristic peak does not mean anything.

Only through repeated experiments and multiple observations of a particle on different detectors and different colliders, so that the confidence of the particle on multiple detectors reaches 5sigma or more, the particle can be confirmed for "discovery".

Hearing Senior Brother Yan say this, Lu Zhou didn't say anything else.

Soon, the experiment continued.

A series of green dots spread densely on the image, and most of the dots are concentrated in the area below the dividing line of 125GeV.

However, Lu Zhou still couldn't let go of the point where 750GeV appeared, and his attention was still tied to that energy zone.

Then at this moment, another point suddenly jumped to the position of 750GeV energy region.

At this moment, Lu Zhou's heart suddenly moved. He looked at Professor Greer next to him and asked, "Where's the data on the CMS detector?"

There are many detectors in one orbit, among which ATLAS and CMS are the two detectors with the highest sensitivity, and have even been used to search for dark matter.

There is a very simple way to test whether the anomaly he discovered is an illusion, that is, the same phenomenon is observed by two detectors at the same time.

Hearing Lu Zhou's question, Professor Greer was slightly stunned, and replied with a puzzled expression.

"...The data collected by the CMS detector is in charge of the upstairs laboratory. If you are curious, I can take you there after the experiment is over, but I can't leave now."

Lu Zhou then asked: "Will the impact data measured during these test runs be recorded?"

Professor Greer nodded: "Generally, it will be archived, but it doesn't have much reference value. I can make a copy for you if you need it. It's not confidential anyway. But I have to remind you that this future Public experimental data, if you want to cite it in the paper, it is impossible."

Standing by the side, Senior Brother Yan asked curiously, "What did you find?"

Lu Zhou thought for a while, and finally insisted on his point of view, and said: "I always feel that there is something wrong with the data in the energy region of 750GeV. Even if it is explained from a statistical point of view, this obvious bulge is described as random. Events always feel a little far-fetched."

Senior Brother Yan joked, "From the perspective of a mathematician?"

Lu Zhou: "That's right."

Brother Yan sighed and said: "I know that your research direction is mathematical physics, but I have to remind you that although mathematics is an important tool for studying theoretical physics, not all physical phenomena must conform to mathematical laws. From theoretical physics From a scientific point of view, the number of 750GeV... is too heavy. You must know that the Higgs particle is only 125GeV. Maybe you think you have discovered a new particle, but in my opinion it is just a two-photon signal, and there may even be no collision at all."

Patting Lu Zhou on the shoulder, Senior Brother Yan continued, "Don't worry about the energy range after 10GeV, we are looking for pentaquark particles this time. If it is because of obsessive-compulsive disorder, you can rest assured that in the experiment later , you will never see the 750GeV phenomenon again."