How Do You Calculate Flavor-Spin Wavefunctions in Quantum Chromodynamics?

In summary, the two papers take their operation from a text that does not explicitly show how they get it or what wavefunctions they use. I assume this is because it is ELEMENTARY, but everytime I try to find this information I get different wavefunctions using different approaches. I'm wondering where should I start. I feel like this should be a simple multiplication, but everytime I try it I don't get their answers.
  • #1
Hepth
Gold Member
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I'm having a little trouble recreating some things from a paper and it is due to my lack of knowledge of working with Flavor-Spin wavefunctions.
I'm trying to show that :
[tex]
\left\langle \Lambda \left|b_s^{\dagger }b_b\right|\Lambda _b\right\rangle =\frac{1}{\sqrt{3}}
[/tex]
and
[tex]
\left\langle p \left|b_u^{\dagger }b_c\right|\Lambda _c^+\right\rangle =\frac{1}{\sqrt{2}}
[/tex]

These two papers both take their operation from the same text, but none of it explicitly shows how they get it or what wavefunctions they use. I assume this is because it is ELEMENTARY but while searching around, many books/articles give different wavefunctions using different approaches.

I'm wondering where I should start. I feel like this should be a simple multiplication but everytime I try it I don't get their answers.

From you guys, do any of you know offhand know the flavor-spin states for a lambda and p (both in s=1/2)? One paper gives both octet proton flavor wavefunctions as :
[tex]p'=\frac{1}{\sqrt{2}}(\text{udu}-\text{duu})[/tex]
[tex]p\text{''}=\frac{1}{\sqrt{6}}(2\text{uud}-\text{duu}-\text{udu})[/tex]

Which is right? Or is it that only in a linear combination with some spin states to make the total flavor-spin function symmetric :
[tex]\left.|56,S=\frac{1}{2},8\right\rangle =\frac{1}{\sqrt{2}}(p'\chi '+p\text{''}\chi \text{''})[/tex]

where the spinors are pretty much the same as the protons function but with spin arrows up and down instead of "u u d".

Am I on the right track?
 
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  • #2
Also, if I get something like:

[tex]u^{\dagger } u^{\dagger } d^{\dagger } u c^{\dagger } d u c[/tex]

and I believe its the trace of this (since i summed over spin states?)
Is there a way to simplify? I know I can cyclically permutate traces to simplify, but that doesn't help this one.
Since I'm summing over spin, and this is merely the flavor representation, can I interchange any two operators freely? Or it would add the (-1) because its not symmetric as just the flavor representation in s=1/2?

If that's the case, then this would simplify to:
[tex]- u^{\dagger} u u^{\dagger} u d^{\dagger} d c^{\dagger} c[/tex]

Which is just -1?

If I follow that method, I get something that isn't what they have. Or am I way off?
 
  • #3
Ok, so no responses. Let me clean up my questions then.

From Appendix A (Page 25&26) of http://arxiv.org/PS_cache/hep-ph/pdf/9304/9304286v1.pdf

I have, in their choice of wavefunctions for a proton and a lambda_c:

[tex]p=\frac{1}{\sqrt{3}}\left[u u d \chi _s +(13)+(23)\right][/tex]
[tex]\Lambda _c^+=\frac{-1}{\sqrt{6}}\left[(u d c- d u c) \chi _A +(13)+(23)\right][/tex]
[tex]\chi _s=\frac{1}{\sqrt{6}}\left[a^{\uparrow } b^{\uparrow } c^{\downarrow }-a^{\uparrow } b^{\downarrow } c^{\uparrow }-a^{\downarrow } b^{\uparrow } c^{\uparrow }\right][/tex]
[tex]\chi _A=\frac{1}{\sqrt{2}}\left[a^{\uparrow } b^{\downarrow } c^{\uparrow }-a^{\downarrow } b^{\uparrow } c^{\uparrow }\right][/tex]

Where (13) is just the permutation.

I'm trying to show that:[tex]N_{\text{fi}}=\, _{\text{flavor} \text{spin}}\left\langle \Lambda \left|b_s^{\dagger }b_c\right|\Lambda _c^+\right\rangle {}_{\text{flavor} \text{spin}}=\frac{1}{\sqrt{3}}[/tex] (in http://arxiv.org/PS_cache/hep-ph/pdf/9502/9502391v3.pdf, bottom of page 13, same author)

and
[tex]N_{\text{fi}}=\, _{\text{flavor} \text{spin}}\left\langle p\left|b_u^{\dagger }b_c\right|\Lambda _c^+\right\rangle {}_{\text{flavor} \text{spin}}=\frac{1}{\sqrt{2}}[/tex] (page 18, same article)I've tried working it out by hand, I don't htink I'm doing it right because I keep getting 3/Sqrt[6] for the proton one, and I get 1 for the lambda_c to lambda.

I know I shouldn't get one, I think I'm doing the operator wrong.

What would I do for the 2 quark flavor spin operator here? Does it replace all c's with u's? Or does it affect spin in any way? Etc. I know its killing off the c, and creating a u, but how does that individually affect "u c d" parts of the wavefunction?

Please help guide me, I just can't seem to do it correctly. ANY help will be amazing.

-hepth
 
Question 1:

What are flavor spin wavefunctions?

Flavor spin wavefunctions are mathematical functions used to describe the properties and behavior of subatomic particles known as quarks. These functions take into account the spin and flavor of the quarks, which are two important characteristics that determine their behavior.

Question 2:

How are flavor spin wavefunctions used in particle physics?

Flavor spin wavefunctions are used to describe the behavior of quarks and other subatomic particles in particle physics experiments. They provide important information about the properties of these particles, which can help scientists understand the fundamental forces and interactions at play in the universe.

Question 3:

What is the relationship between spin and flavor in flavor spin wavefunctions?

Spin and flavor are two independent properties of subatomic particles, but they are closely related in flavor spin wavefunctions. Spin refers to the intrinsic angular momentum of a particle, while flavor refers to its identity or type (such as up, down, charm, etc.). Flavor spin wavefunctions take into account both of these properties in describing the behavior of particles.

Question 4:

How do flavor spin wavefunctions contribute to our understanding of the Standard Model of particle physics?

The Standard Model is a theory that describes the fundamental particles and forces that make up the universe. Flavor spin wavefunctions play a crucial role in this model by providing information about the properties and behavior of quarks, which are one of the building blocks of matter according to the Standard Model.

Question 5:

Are there any limitations or challenges in using flavor spin wavefunctions?

Like any mathematical model, flavor spin wavefunctions have their limitations and challenges. For example, they may not accurately describe particles under extreme conditions or in certain interactions. Additionally, there are still many unanswered questions and mysteries surrounding the behavior of quarks, which may require new or modified flavor spin wavefunctions to fully understand.

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