Recent content by sgd37

I'd be careful here because the RHS gives \frac{\partial}{\partial x^{\mu}}\delta^4(x-y) whilst the LHS gives you \frac{\partial}{\partial y^{\mu}}\delta^4(y-x) if you set t=x-y and use the identity you gave above you can see that \frac{\partial}{\partial...

Forgive me what I should have said is you don't have to transfer the space-time derivative. You are free to do so

Use the defining equations for the center of mass R and relative position r

You don't use integration by parts to transfer the spacetime derivative onto PsiBar since \; \dfrac{\delta \psi_i(x)}{\delta \psi_j(y)} = \delta_{ij} \, \delta^{(4)}(x-y) = \dfrac{\delta \bar\psi_i(x)}{\delta \bar\psi_j(y)} you have the choice over which delta function you integrate first...

Do you mean the Hopf map http://mathworld.wolfram.com/HopfMap.html

Have you checked if (\star(e\wedge e)+\frac{1}{\gamma}e\wedge e)|_{\Sigma} obeys the so(1,3) algebra commutation relations

I think there is a sign error somewhere because all you're showing is that \partial (\psi^*\partial\psi)+\frac{ie}{\hbar c}\partial\psi A \psi is real i.e. z-z^*=2Im(z) which is not a trivial statement for complex fields

Homework Statement Hi I need to regularize \sum_{r \in Z+1/2} r In my opinion there are two ways of going about it either re-express it as \sum_{r \in Z+1/2} r = \sum_{r =1} r - \frac{1}{2} \sum_{r =1} = \zeta (-1) - \zeta (0) = \frac{1}{6} or \sum_{r \in Z+1/2} r =...

Ok by intend I mean I am applying for PhD's sorry for the ambiguity. All of them require a Research Proposal and without a concrete project to apply for I am at a loss as to what to put in the proposal. If anyone who has successfully obtained a Mathematical physics (string theory super sym...

Hi I intend to apply for a PhD in Mathematical physics My question is how does one write a research proposal without an in-depth understanding of the subject or its research possibilities. Can I ask the potential supervisor for assistance in writing it thank you

Unfortunately my BSc project was the only bad mark I had and I chose not to do one at Part III (mistake in retrospect) so I have only my grades. I have considered the 4 year PhD's and had applied to some with no success (Durham). The main attraction of an european master's is the dissertation at...

I've had more hard looks at myself since I left uni than I care to mention. I've even tried to abandon it all and do something completely unrelated. It seems that physics is the only thing I'm remotely good at. The only thing I may be trying to prove is that the Part III grades don't represent...

thanks for the reply and perspective Although I agree that a bad partIII + MSc (a good one I hope) will not trump the part III distinctions, they still are a limited number of those each year joining the pool. My hope is that a good MSc from a good European institution with an interesting...

Hi I would be grateful for some advice I graduated two years ago from Cambridge with a Pass (nowhere near high marks) in PartIII and I finished my Bsc with first class honours. I've tried getting a PhD placement at several universities in the UK with no success. I am thinking about trying...

this is a problem in anti commutation. Anti commute the annihilation operators past all the other operators so that they may annihilate the vacuum, in other words you have to normal order the operators