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bolbteppa

6:00 PM

Literally $1/2$ ruining everything :(

Danu

I'm not even gonna try to look at that :P

But I have a document that does the derivation, I think.

So I can send you that

bolbteppa

I'll type it up quick

Danu

Actually, scratch that

I don't have it

Sorry, you're on your own.

Jaime Gallego

I am sold

"Join hundreds of thousands of people just like you who are taking pictures of headstones all over the world!"

0celouvsky

Wow, that's my hobby!

Anonymous

6:13 PM

@JaimeGallego That seems silly at best....

Anonymous

:-P

Anonymous

What would be its use ?

bolbteppa

Let me start again:

If you set up $S = \int dt ( \dot{x}^{\mu} p_{\mu} - \frac{e}{2}p^{\mu}p_{\mu} - \frac{i}{2} \chi_{\mu} \dot{\chi}^{\mu} - \frac{ik}{2} \psi \chi^{\mu} p_{\mu})$ and eliminate the momentum via it's eom to get $p_{\mu} = e^{-1}(\dot{x}_{\mu} - \frac{ik}{2}\psi \chi_{\mu})$ and plug it in to that action, you're supposed to get $S = \int d t \frac{1}{2}(e^{-1}\dot{x}^{\mu} \dot{x}^{\nu} - i \chi^{\mu} \dot{\chi}^{\nu} - i k e^{-1} \psi \dot{x}^{\mu} \dot{\chi}^{\nu}) \eta_{\mu \nu}$
but I keep getting extra terms:

\begin{align}
S &= \int dt ( \dot{x}^{\mu} p_{\mu} - \frac{e}{2}p^{\mu}p_{\mu} - \frac{i}{2} \chi_{\mu} \dot{\chi}^{\mu} - \frac{ik}{2} \psi \chi^{\mu} p_{\mu}) \\
&= \int dt \{ \dot{x}^{\mu} e^{-1}(\dot{x}_{\mu} - \frac{ik}{2}\psi \chi_{\mu}) - \frac{e}{2}[e^{-1}(\dot{x}^{\mu} - \frac{ik}{2}\psi \chi^{\mu})][e^{-1}(\dot{x}_{\mu} - \frac{ik}{2}\psi \chi_{\mu})] \\
& \ \ \ \ \ \ \ \ - \frac{i}{2} \chi_{\mu} \dot{\chi}^{\mu} - \frac{ik}{2} \psi \chi^{\mu} (e^{-1}(\dot{x}_{\mu} - \frac{ik}{2}\psi \chi_{\mu}))\} \\

Have to be missing a $1/2$ somewhere, any thoughts?

Sir Cumference

6:45 PM

Testing

skull petrol

Litmus test?

DanielSank

Hi, everybody.

skull petrol

Hello.

How's it going?

DanielSank

good

Laying out circuit board.

It's fun.

0celouvsky

7:30 PM

@ACuriousMind what's a C* tensor category?

I was tricked into going to a "quantum topology" seminar

DanielSank

7:57 PM

@0celouvsky Did you learn about the toric code?

You might appreciate the mathematics in that.

It's extremely interesting. You can use a period lattice of 2-level quantum systems as an effective single 2-level system whose quantum coherence is preserved even when a subset of the constituent systems suffer random state changes.

This is very much not obvious.

And it's the basis of how we think you can actually build a quantum computer.

Look up Kitaev's paper on the "toric code".

0celouvsky

I did not because I don't think you told me the right paper.

bolbteppa

Driving me nuts

0celouvsky

Or I did start reading it but knew zero words so I lost interest.

bolbteppa

Q: Extra Term in Super Particle Action

If you set up the first order formulation of $$S = \int dt \frac{1}{2}(\dot{x}^{\mu} \dot{x}_{\mu} - i \chi^{\mu} \dot{\chi}_{\mu})$$ incorporating the constraints $$p^{\mu} p_{\mu} = 0, \chi^{\mu} p_{\mu} = 0$$ as a constrained Lagrangian $$S = \int dt ( \dot{x}^{\mu} p_{\mu} - \frac{e}{2}p^{\...

There is a tiny tiny reason to believe you throw away $k^2$ order stuff, but noooo

Sebastiano

good evening to everybody

can i have an general answer for this site?

Sebastiano

8:21 PM

@JohnRennie @ACuriousMind kind, it may be that this is the only site of Physics there are always problems when I ask a question after reading the instructions of how to formulate a question?

Physics Meta

8:59 PM

Q: Citation tool on Math.SE, can we get it?

I was just about to ask a question on math.se when I saw they had a new (I think) tool: From what I can tell it allows a quick way to search and include references in questions and answers: I think this would be very useful on physics.se - are there any plans for is to get it? if so when an...

feature-request citation

Q: Looking for a back end for a Physics SE literature citation button

The question Citation tool on Math.SE, can we get it? showcases a really nice feature that started as a userscript some three years ago and which has now been officially enabled on MathOverflow and Math SE, which enables direct and easy referencing to papers in the literature. Unfortunately, how...

discussion citation

Q: I am just a kid can I be on this site?

Can I a kid be on this site and ask Questions? I want to but I think they would be silly

discussion

Emilio Pisanty

9:40 PM

Go home @PhysicsMeta, you're drunk

@DanielSank this might be of interest

Nova

Hi all, I have a quick question about vapor pressure vs partial pressure

0celouvsky

10:02 PM

Vape nashe y'all

DanielSank

10:58 PM

@EmilioPisanty Woah!

0celouvsky

11:54 PM

@AccidentalFourierTransform Ok. Then you are correct. I never knew this way of thinking about the metric. I always thought of $ds^2$ as a scalar invariant interval. — Electrodynamist 2 days ago

@AccidentalFourierTransform poor guy

@ACuriousMind hola