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Xi decay quarks conserved but flavour not conserved

by Howlin
Tags: conserved, decay, flavour, quarks
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Howlin
#1
Nov13-12, 07:12 AM
P: 45
Hi

I have been looking into particle physics and i came across this question but i can not find the answer,

the quetsion is as follows:

the xi particle decays into the following
[itex]\Xi -> \wedge + \Pi^{-}[/itex]
dds -> sud + [itex]\overline{u}d [/itex]
the quark numbers are conserved but the flavours are not conserved.

I cannot understand why the flavours are not conserved. Can anyone help me?
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mfb
#2
Nov13-12, 07:38 AM
Mentor
P: 11,576
the flavours are not conserved.
Where does that come from?
Looks conserved to me.

The long lifetime (~10-10s) is suspicious.
Howlin
#3
Nov13-12, 07:53 AM
P: 45
It says on it why isnt it conserved and is it decayed by strong or weak forces.
I would say weak because flavours are not conserved but by looking at it, it seems to be conserved

mfb
#4
Nov13-12, 08:10 AM
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P: 11,576
Xi decay quarks conserved but flavour not conserved

Well, it is easy to draw a diagram for the strong interaction.

The long lifetime indicates that those diagrams are problematic in terms of parity, or cancel each other partially, or something else.

Edit @Bill_K's post: Oh, that explains everything. And ##\Sigma^-## with dds is too light to decay into ##\Lambda + \pi##
Attached Thumbnails
decay.jpg  
Bill_K
#5
Nov13-12, 08:29 AM
Sci Advisor
Thanks
Bill_K's Avatar
P: 4,160
The Ξ- (aka cascade particle) is not dds, it's dss. The decay is weak because it does not conserve strangeness.


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