Recent content by ppedro

How can I anti-commute with something that's in the exponent?

I don't see it... Do you mean I should use that in (i) while also applying BCH's formula?

Consider the Dirac Lagrangian, L =\overline{\psi}\left(i\gamma^{\mu}\partial_{\mu}-m\right)\psi, where \overline{\psi}=\psi^{\dagger}\gamma^{0} , and show that, for \alpha\in\mathbb{R} and in the limit m\rightarrow0 , it is invariant under the chiral transformation...

What do you mean? Cavity dumping doesn't make use of the kind of mechanism that I was wondering about the possibility of existence. I was wondering if it is possible to control the resonant stability of the cavity to somehow reduce or event prevent lasing and then turn it on at some point to...

Does anyone know if there's any q-switching technique that makes use of an unstable resonant cavity (or some kind of switching of the cavity between stable and unstable) to achieve the pulse output?

Thanks for the input. Yes, that definition gives the computed answer. However, the textbook does not strictly define the area of the spot nor gives a reason for that choice in this particular problem. There are several possible definitions and my answer is the one using ##I=e^{-2}I_{max}##.

Hi friends! I solved the problem 8.3 of ``Problems in Lasers Physics'' book (by Cerullo, Longhi, Nisoli, Stagira and Svelto) but I think there's a mistake on the solution presented in this book in page 196. This is a problem book with problems and solutions that follows closely the laser...

Thanks @jedishrfu !

Hi friends, I have to do a semester project (analytic, computational, or both) for my second course in Statistical Physics - a graduate level course with great emphasis on phase transitions. It will be graded just 15% of the final grade (so, it is not necessary to elaborate exhaustively) and it...

I've done many exercises about inertia tensors of 3D bodies and sticks but now I have this exercise and I got stuck without any idea of how to do the integration to compute the inertia tensor. The statement is this: "Compute the inertia tensor of a cross-hanger consisting of 3 thin and linear...

Thanks TSny! It makes sense. But that would mean the answer in the solution sheet I shared is wrong, right?

Hi! I'm having an hard time with a trivial question that suddenly I can't figure out: Computing the potential between the plates of a spherical capacitor. The problem is taken from this url (first page and a half)...

I saw I made a careless mistake on the last step of my approach. I was summing the terms where they should be multiplied. So I end up with =N^{N}\left(N-n\right)^{n-N}e^{-n}=e^{-n}\frac{N^{N}}{\left(N-n\right)^{N-n}}=e^{-n}N^{n}\left(\frac{N}{N-n}\right)^{N-n} and I see that...

I'm afraid I don't know how to do it. Could you write it explicitly? Many thanks

I understand what you wrote in the first line. I have n factors involving N minus something which is to be small compared with N. But I should be able to say it formally.