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From: Julian Bradfield on 5 Jan 2010 18:27
On the off chance that there are still some physicists lurking here -
is it possible to give an intuitive explanation of why spin 1/2
baryons with three same-flavour quarks do not exist?
A wikipedia article says "because of Pauli exclusion", but I can't see
how to use this.

On a similar note, is there a way to explain intuitively the
difference between Lambda^0 and Sigma^0 without using the word
"isospin"?

Intuitive means "suitable for a six-year old" - so no
3 \otimes \overline{3} = 1 \oplus 8 \oplus 8 \oplus 10 !
From: Androcles on 5 Jan 2010 18:44

"Julian Bradfield" <jcb(a)inf.ed.ac.uk> wrote in message
news:hi0hsk$cl1$1(a)scotsman.ed.ac.uk...
> On the off chance that there are still some physicists lurking here -
> is it possible to give an intuitive explanation of why spin 1/2
> baryons with three same-flavour quarks do not exist?
> A wikipedia article says "because of Pauli exclusion", but I can't see
> how to use this.
>
> On a similar note, is there a way to explain intuitively the
> difference between Lambda^0 and Sigma^0 without using the word
> "isospin"?
>
> Intuitive means "suitable for a six-year old" - so no
> 3 \otimes \overline{3} = 1 \oplus 8 \oplus 8 \oplus 10 !

What you need is a theoretical physicist, not a real one.
As for intuition, the Sun circles the flat Earth as any six-year-old
understands intuitively. He can see it does. Reason may say otherwise
but that clashes with his intuition. It takes a lot of careful explaining
from an early age to overcome faith and if the teacher believes
nonsense then who does the child turn to for enlightenment?


From: Mike Jr on 5 Jan 2010 23:29
On Jan 5, 6:27 pm, Julian Bradfield <j...(a)inf.ed.ac.uk> wrote:
> On the off chance that there are still some physicists lurking here -
> is it possible to give an intuitive explanation of why spin 1/2
> baryons with three same-flavour quarks do not exist?
> A wikipedia article says "because of Pauli exclusion", but I can't see
> how to use this.
>
> On a similar note, is there a way to explain intuitively the
> difference between Lambda^0 and Sigma^0 without using the word
> "isospin"?
>
> Intuitive means "suitable for a six-year old" - so no
> 3 \otimes \overline{3} = 1 \oplus 8 \oplus 8 \oplus 10  !

Does Bell's inequality make it any easier?
http://arxiv.org/abs/hep-th/9701089

--Mike Jr.
From: nuny on 6 Jan 2010 02:08
On Jan 5, 3:27 pm, Julian Bradfield <j...(a)inf.ed.ac.uk> wrote:
> On the off chance that there are still some physicists lurking here -
> is it possible to give an intuitive explanation of why spin 1/2
> baryons with three same-flavour quarks do not exist?
> A wikipedia article says "because of Pauli exclusion", but I can't see
> how to use this.

It's not obvious. The individual spins of the quarks must be added
according to a set of exclusion rules, the orbital angular momentum of
the quarks about each other also must be added according to a
different set of rules, then the spin and orbital angular momenta must
be added:

(beware link wrap)
http://en.wikipedia.org/wiki/Baryons#Spin.2C_orbital_angular_momentum.2C_and_total_angular_momentum

> On a similar note, is there a way to explain intuitively the
> difference between Lambda^0 and Sigma^0 without using the word
> "isospin"?

No.

> Intuitive means "suitable for a six-year old" - so no
> 3 \otimes \overline{3} = 1 \oplus 8 \oplus 8 \oplus 10  !

Glad to help.


Mark L. Fergerson
From: eric gisse on 6 Jan 2010 02:40
Julian Bradfield wrote:

> On the off chance that there are still some physicists lurking here -
> is it possible to give an intuitive explanation of why spin 1/2
> baryons with three same-flavour quarks do not exist?
> A wikipedia article says "because of Pauli exclusion", but I can't see
> how to use this.

You can't have Fermions (non-integer spin) share a quantum state with
another Fermion.

>
> On a similar note, is there a way to explain intuitively the
> difference between Lambda^0 and Sigma^0 without using the word
> "isospin"?
>
> Intuitive means "suitable for a six-year old" - so no
> 3 \otimes \overline{3} = 1 \oplus 8 \oplus 8 \oplus 10 !

You want the standard model of particle physics reduced to a six year old's
level of understanding? Wake me when that's been done for law.


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