Recent content by Kyleric

I'd like to know if creation and annihilation operators are involved in a free trajectory of a particle from point A to point B. If it's the case, how so? If there is a detector at A, and another one at B, mathematically speaking, can it be said that the particle is annihilated at A, and...

True for numbers, but the components of the Lagrangian are operators. Yes that's what I was thinking also. But they took the approximation as a step towards a discussion about spontaneous symmetry breaking in QCD, so it was very well motivated.

Ok nevermind, it's just from the Dirac equation.

Say we have a Lagrangian \mathcal{L}=\bar{u}i\kern+0.15em /\kern-0.65em Du+\bar{d}i\kern+0.15em /\kern-0.65em Dd-m_u\bar{u}u-m_d\bar{d}d, where u and d are fermions. In Peskin&Schroeder p. 667 it says that if m_u and m_d are very small, we can neglect the last two terms of the Lagrangian. I'd...

I did it at Université de Montréal, in Canada. Yes it's possible to fail. I sent another e-mail to a professor and apparently the evaluation in all these courses will be done on the basis of an oral presentation. That makes the ordeal somewhat less scary.

I've been accepted in the M2 (2nd year of master's) program in high energy physics at Ecole Polytechnique, in Paris. I looked at the compulsory courses I'd have to take. Here they are: -Beyond the standard model, supersymmetry and supergravity; -The standard model - weak and strong...

Great, thanks. For those interested there's a very informative thread about this subject at https://www.physicsforums.com/showthread.php?t=252102

How do you know that it describes particles of spin 1? From experiment, or is there are mathematical proof?

"Experimental evidence like the hydrogen fine structure and the Stern-Gerlach experiment suggest that an electron has an intrinsic angular momentum, independent of its orbital angular momentum. These experiments suggest just two possible states for this angular momentum, and following the...

Before coming to the initiation at the start of the major in physics we had to do a quiz measuring "how much of a physicist are you". For each question we'd answer yes or no and get points for each 'yes'. At the initiation we had to wear a name tag with our score on it. One of the questions was...

I applied to three universities to enter a PhD program in string theory (I know, it's not much). All three rejected me. One of them rejected me purely for financial reasons. Since I am motivated, I bargained with it to start my PhD without financial support and got accepted. It's possible I...

I fell into depression during my last undergraduate year and had to stop for a whole year. My problem was that I went into a tunnel vision, was studying 7days/week, sometimes 10h/day. I put all my energy into academic work, and neglected the small things in life, and some big ones. I think...