Overview of processes

We are now trying to understand from a birds eye view the different processes.

First, we can see that the beam is coming from the bottom of the page and then moving upwards. We can say this, because looking top down, we had to assume that two particles unite to one. 

Second we have to know that the beam of incoming particles is a beam of K- particles. We cannot know this. The experimenters have to tell us.

The K- now collides with a proton. For an explanation of the difference between a collision and a decay, click here. The collision process is the following:

After a short while, the decays into a pair of and .

To see that this interpretation is right, we have to ensure, that the following rules are holding:

The first two are subject to careful interpretation of the course of the particles. The final criterion is the total momentum of the outgoing 4 particles, which have to be the same as the momentum of the incident K- particle. If they do not match, then we have either a particle, which we did not find, or the interpretation of the interaction is wrong.

The other conservation laws are easier to prove, as shown in the table.

Property/Particle		p	->	p
Q	-1	+1	=	+1	-1	0
B	0	+1	=	+1	0	0
S	-1	0	=	0	0	-1

In this table you can see, that the conservation of charge and baryon number holds.

But as the particle is not visible in the original bubble chamber photo, we might wonder how just to name it?

One typical indicator is the VEE, pointing to the point of interaction. Such a VEE comes up, when a K0 particle or a Lambda particle or its antimatter counterparts decay to a pair of charged particles of opposite charge (Click here for details).

The  decays of these particles are:

• <- Click for Feynman diagram
• <- Click for Feynman diagram
• <- Click for Feynman diagram
•  

We see that the first two decays end up in the same pair of particles so we cannot really distinguish between these two kaons.

Additionally, these two kaons undergo transitions to each other. So in the end, you cannot say whether the two emerging pions result from a or a . We choose the because in this case the corresponding Feynman Diagramm is easier to understand.

But at a first glance we would assume that the two lambda decays are not so like because proton or antiproton are assumed to leave a strong track with a different curvature than the pion. The quantum numbers give us a short proof, which holds, because the collision interaction of the K- with the proton is a strong interaction.

Property/Particle		p	->	p
Q	-1	+1	=	+1	-1	0
B	0	+1		+1	0	+1
S	-1	0	=	0	0	-1

Property/Particle		p	->	p
Q	-1	+1	=	+1	-1	0
B	0	+1		+1	0	-1
S	-1	0		0	0	+1

So this overview over these quantum numbers exclude the lambda particles from being the ones who decay.

A final proof nevertheless must always be the comparison of the sum of momentum and energy of the outgoing particles towards the momentum and energy of the incoming particle. We do get these data only by interpretation of the tracks data.

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