All Questions
Tagged with standard-model conservation-laws
132
questions
22
votes
2
answers
2k
views
Have all the symmetries of the standard model of particle physics been found?
Background
The standard model of particle physics is entirely determined by writing down its Lagrangian or, equivalently, writing down the corresponding system of PDEs.
Every set of PDEs has a ...
- 323
5
votes
2
answers
612
views
Is the number of electrons in the universe always the same?
My teacher just said the number of electrons in the universe always stays the same, that's not how I understood weak force interactions and electron capture. Is there some rule that states that the ...
- 341
0
votes
1
answer
90
views
How to determine the charge of a $W$ boson in a Feynman diagram?
As the title says, I am not sure in what situations there is a W$^+$ boson and when there is a W$^-$ boson. My lecturer explained to me that you can view it either as the $W$ boson supplying a charge ...
- 1
5
votes
3
answers
199
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What is the connection between matter in the universe and the baryon number not being conserved?
Towards the end of "Quarks, the Stuff of Matter", the author discusses the implications of the proton is not stable and ultimately decays. He states, that if the proton decays, then the ...
- 2,706
1
vote
1
answer
98
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Possible orbital angular momentum values in the weak decay of $B_s \rightarrow J/\psi+\phi$
So $B_s$ has $J=0$, and both the decay products have $J=1$. $J$ is conserved, so the joint final state must also have $J=0$, and I'm told the final joint state can have orbital angular momentum values ...
- 33
0
votes
1
answer
123
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Is spin conserved in a reaction between elementary particles?
I was making an exercise where I had to check if a decay is possible, so I checked if the baryon number, charge, energy, Lepton numbers, and spin are conserved. One of the decays is this one:
$\Sigma^...
- 27
-2
votes
1
answer
52
views
Isn't weak interactions necessarily violate strangeness?
The electron-proton elastic scattering process $$e^-+p^+\to e^-+p^+$$ can take place either via a photon exchange (electromagnetic interaction) or via $Z^0$ exchange (weak interaction). But isn't weak ...
- 11.8k
0
votes
1
answer
45
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A very basic question about particle (leptons, hadrons) interactions
Suppose a particle reaction $A+B\to C+D$ is allowed in nature. Then, the reactions,
\begin{align}
A&\to \bar{B}+C+D,\\ \bar{C}+\bar{D}&\to \bar{A}+\bar{B},\\ B&\to\bar{A}+C+D,\\& \...
- 11.8k
0
votes
2
answers
136
views
EM force or Strong force?
$$
e^- + p \rightarrow \Delta^{++} + e^- + \pi^-
$$
Apparently this reaction is mediated by the EM force. My question is: how do you know it isn't the strong force?
Yes, all the particles have ...
- 101
0
votes
2
answers
274
views
$\Sigma^0$ particle decay
I was asked to evaluate whether the following reaction is possible or not:
$$\Sigma^0 \rightarrow \Lambda + \pi^0$$
I have evaluate all conservations law that could prevent it to occur, but i haven't ...
- 980
2
votes
0
answers
71
views
What happens to spin when bosons exchange bosons?
I understand that spin is a conserved quantity, I also understand that gluons can exchange gluons, and $W$ bosons exchange photons. However, when I try to combine these concepts, I can't figure out ...
2
votes
1
answer
226
views
How to check whether particle interaction is allowed and how to classify interactions?
My question would be (as I couldn't find a website summarising it) to have a comprehensive list of how to check whether a particle interaction is allowed and if so, what interaction it is (or it would ...
- 23
1
vote
1
answer
217
views
How to determine where a gluon should be emitted in a Feynman diagram?
I have been learning how to draw Feynman diagrams for various decays. I just came across an interesting video where they draw the following diagram for $K^+ \to 2\pi^++\pi^-$:
My question is as ...
- 179
-1
votes
1
answer
201
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Can an elementary particle truly be destroyed?
Much like the title above, can they be created (from absolute nothing) or destroyed (into absolute nothing), with nothing in this case being nonexistence. Taking into account the idea of quantum ...
- 3
0
votes
1
answer
160
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What are the symmetries of standard model and its conservation laws? [closed]
Is there like a list of symmetries in the standard model with associated conservation laws?
- 11