Understanding Branch Points for (1-z^3)^{1/2}

In summary: Hi BWV! :smile:In summary, the branch points for z=1, z=\omega and z=\omega^2 are the zeros of the function.
  • #1
BWV
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[itex](1-z^3)^{1/2}[/itex] has three branch points at [itex]z=1, z=\omega[/itex]and [itex]z=\omega^2[/itex] where [itex]\omega = e^{2\pi i/3}[/itex]

The branch points are the zeros of the function correct?

So why are not [itex]z=\omega^4[/itex], [itex]z=\omega^6[/itex], [itex]z=\omega^8[/itex] etc also branch points as they are zeros of the function?
as
[itex](e^{2\pi i/3^3})^6[/itex] =[itex]e^{2\pi i^6}[/itex] = [itex]e^{12\pi i}[/itex] = 1 so all even numbered powers of [itex]\omega[/itex] are zeros of the function

also why does the latex code move around vertically like this?
 
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  • #2
Hi BWV! :smile:

[tex](\omega^{n})^3 = 1[/tex] for any n:

[tex](\omega^{n})^3 = (e^{\frac{2n\pi}{3}})^3 = e^{2n\pi} = (e^{2\pi})^n = 1[/tex] :smile:

also why does the latex code move around vertically like this?

If you mean why doesn't it stay on the same line as ordinary text, the answer is:

:biggrin: 'cos it doesn't! :biggrin:

But you can make it stay on the line by using [noparse][itex] and [/itex] instead of [tex] and [/tex][/noparse] ("itex" stands for "inline tex") … but that has the disadvantage that it squeezes it vertically into the line, so fractions and powers get squashed. :mad:

Alternatively, you can type the whole thing in latex, enclosing each bit of ordinary text inside the brackets of "\text{}":smile:
 
  • #3
BWV said:
[itex](1-z^3)^{1/2}[/itex] has three branch points at [itex]z=1, z=\omega[/itex]and [itex]z=\omega^2[/itex] where [itex]\omega = e^{2\pi i/3}[/itex]

The branch points are the zeros of the function correct?

So why are not [itex]z=\omega^4[/itex], [itex]z=\omega^6[/itex], [itex]z=\omega^8[/itex] etc also branch points as they are zeros of the function?
as
[itex](e^{2\pi i/3^3})^6[/itex] =[itex]e^{2\pi i^6}[/itex] = [itex]e^{12\pi i}[/itex] = 1 so all even numbered powers of [itex]\omega[/itex] are zeros of the function

also why does the latex code move around vertically like this?
[itex]\omega= e^{2\pi /3}[/itex] is the "principal cube root" of 1. That is, [itex]\omega^3= 1[/itex]. We don't talk about [itex]\omega^4[/itex] because [itex]\omega^4= (\omega^3)(\omega)= (1)(\omega)= \omega[/itex]. Similarly, [itex]\omega^6= (\omega)^3(\omega^3)= (1)(1)= 1[/itex] and [itex]\omega^8= (\omega)^3(\omega^3)(\omega^2)= (1)(1)(\omega^2)= \omega^2[/itex].
 

1. What are branch points in a scientific context?

Branch points are specific locations in a scientific model or theory where there is a divergence or change in the predicted outcome or behavior.

2. How do branch points impact scientific research?

Branch points can have a significant impact on scientific research, as they can lead to new discoveries, challenges to existing theories, and further exploration of different paths or outcomes.

3. Can branch points be predicted or identified in advance?

In some cases, branch points can be predicted or identified in advance through various methods such as experimentation, data analysis, and modeling. However, in other cases, branch points may be unexpected and require further investigation.

4. How can branch points be interpreted in scientific studies?

Interpreting branch points in scientific studies can be complex and may require careful analysis and consideration of various factors such as experimental design, data validity, and potential alternate explanations.

5. Are branch points always a result of errors or mistakes in scientific research?

No, branch points are not always a result of errors or mistakes in scientific research. They can also occur naturally due to the complexity of systems and phenomena being studied, and may even lead to new and valuable insights and discoveries.

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