Understanding a p-p collision qualitatively

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In summary, when two protons collide at the LHC and a quark from each undergoes a weak interaction to form a W/Z boson, the remnants of the protons can either continue being themselves or lead to jets, depending on whether the weakly interacted quark was a sea quark or a valence quark. The final state will still contain two protons to conserve baryon number. The process of W/Z boson formation involves the emission of a gluon, which turns into down and down-bar quarks. The down-bar quark then combines with an up quark from the other proton to emit a W+ boson. This can result in a proton and a neutron, but there are
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MarekS
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If two protons collide at the LHC and a quark from each undergo a weak interaction together to form a W/Z boson, then what happens to the remnants of the protons?

I think that if the weakly interacted quark was a sea quark, then the proton can continue being itself, but may lead to jets. If, however, the weakly interacted quark was a valence quark, then the remnant of the proton must lead to jets since a valence u or d is missing. Ultimately, the final state will still contain two protons to conserve baryon number.

Is this correct?

Also, are the two quarks that form the W/Z "ripped out" of the proton or rather one proton enters the other so that the interaction could occur? That is to say, a volume of space normally occupied by one proton is temporarily occupied by two protons and also the newly created W/Z boson?
 
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There are many ways this can happen, so let's describe just one. A W boson couples to the weak current, which for baryons derives from quark-quark bar. Each proton contains three quarks: up, up and down. So say one of the up quarks emits a gluon, which turns into down and down-bar. At this point we have a total of four ups, three downs and a down-bar.

The down-bar combines with one of the up quarks from the other proton, emitting a W+. What we now have left is three ups and three downs. Minimally this could result in a proton and a neutron.

In reality there will be many other processes going on, and numerous other particles produced.
 
  • #3
MarekS said:
I think that if the weakly interacted quark was a sea quark, then the proton can continue being itself, but may lead to jets. If, however, the weakly interacted quark was a valence quark, then the remnant of the proton must lead to jets since a valence u or d is missing.
You cannot point to a quark and say "this is a valence quark!". If you take any quark and let it interact with some parton in the other proton, you always change the quark content, and hadronization has to care about that afterwards.

There are elastic collisions - collisions where one or both protons stay protons. But those correspond to a small momentum exchange, I would be surprised to see a heavy boson produced in an elastic collision. Usually, they form jets.
 
  • #4
The proton remnants go down the beam pipe. They form hadrons, and as you guessed, global baryon number is conserved.
 

1. What is a p-p collision?

A p-p collision is a type of particle collision that occurs between two protons. Protons are subatomic particles found in the nucleus of an atom and they have a positive charge. When two protons collide, a large amount of energy is released and this energy can be used to create new particles.

2. How is a p-p collision studied?

P-p collisions are studied using particle accelerators, which are large machines that accelerate protons to very high speeds before colliding them. These collisions are then observed and analyzed using various detectors to understand the particles and energy produced.

3. What can we learn from understanding p-p collisions?

Studying p-p collisions can help us understand the fundamental building blocks of matter and the forces that govern their interactions. It can also provide insights into the evolution of the universe and the conditions that existed in the early universe.

4. What is the role of quantum mechanics in understanding p-p collisions?

Quantum mechanics is a branch of physics that describes the behavior of particles at the subatomic level. Understanding p-p collisions requires an understanding of quantum mechanics because it governs the interactions between particles and the energy released during collisions.

5. How does understanding p-p collisions contribute to scientific advancements?

Understanding p-p collisions has contributed to many scientific advancements, including the discovery of new particles and forces, and the development of technologies such as medical imaging and cancer treatment. It also helps us improve our understanding of the universe and its origins.

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