Register to reply

Xi decay quarks conserved but flavour not conserved

by Howlin
Tags: conserved, decay, flavour, quarks
Share this thread:
Nov13-12, 07:12 AM
P: 45

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?
Phys.Org News Partner Physics news on
Engineers develop new sensor to detect tiny individual nanoparticles
Tiny particles have big potential in debate over nuclear proliferation
Ray tracing and beyond
Nov13-12, 07:38 AM
P: 11,925
the flavours are not conserved.
Where does that come from?
Looks conserved to me.

The long lifetime (~10-10s) is suspicious.
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

Nov13-12, 08:10 AM
P: 11,925
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
Nov13-12, 08:29 AM
Sci Advisor
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.

Register to reply

Related Discussions
Why is momentum conserved but kinetic energy not conserved in an inelastic collision? General Physics 1
Do up and down quarks obey flavour quantum conservation? High Energy, Nuclear, Particle Physics 7
Dirac conserved current vs Klein-Gordon conserved current Quantum Physics 14
Jumping on a trampoline and energy conserved/ not conserved Introductory Physics Homework 1
Momentum conserved and energy isn't conserved? Introductory Physics Homework 18