Recent content by zardiac

Homework Statement I am asked to draw a feynman diagram of K^- \rightarrow \mu \nu Homework Equations K^- consist of s\bar{u} The Attempt at a Solution I wonder what the direcion of the arrows should be, my guess is something like the attached image. edit: Ah, where the left u shoudl be an...

Homework Statement I am trying to derive the line element for this geometry. But I am not sure how to show that ds can't contain any crossterms of d\theta and d\phi Homework Equations ds must be invariant under reflections \theta \rightarrow \theta'=\pi - \theta and \phi...

Thanks, I understand it better when I plot and look at the asymptotes http://www.wolframalpha.com/input/?i=plot+%7B1%5E2%2F0.2*%28sqrt%281%2B%280.2%29%5E2t%5E2%29-1%29%2C+%28t-1%2F0.2%29%7D++from+t%3D0+to+100 I can see why the lines won't cross if t is too large. But even if it is easy to...

Well it is problem 3.9 in D'inverno Introducing Einsteins relativity. I agree that it seem impossible but the problem statement is that if you get a large enough headstart the light won't catch up.

Homework Statement You start at t=0 at rest on Earth and accelerate with uniform acceleration a away form earth. Find a point in time t_0 such that when a beam emitted from Earth at t>t_0 won't catch up. Homework Equations x(t)=c^2/a(\sqrt{1+\frac{a^2}{c^2}t^2}-1) The Attempt at a...

Ah of course, there are some elements that are zero. I don't know why I didn't checked that first. Thanks for quick replies, I think I got it right now :)

Homework Statement Compute 21 elements of the Riemann curvature tensor in for dimensions. (All other elements should be able to produce through symmetries) Homework Equations R_{abcd}=R_{cdab} R_{abcd}=-R_{abdc} R_{abcd}=-R_{bacd} The Attempt at a Solution I don't see how 21...

Really? I guess I am not used to the einstein notation contention. How can you see what indexes are free and which ones are dummy? I thought since I was to determine L_v(u_a) then a was a free index, and thus if I change in one of the terms I have to change in all of the terms. (Which would not...

Homework Statement Derive L_v(u_a)=v^b \partial_b u_a + u_b \partial_a v^b Homework Equations L_v(w^a)=v^b \partial_b w^a - w^b \partial_b v^a L_v(f)=v^a \partial_a f where f is a scalar. The Attempt at a Solution In the end I get stuck with something like this, L_v(u_a)w^a=v^b...

I am not sure why (ab)^{mn} = 1 is clear. (a)^{n} = 1 and (b)^{m} = 1 but does that say anything about (ab)^{mn} ? Sorry maybe to early in the morning for this, Ill think about what you wrote during the day and see where I get! Thanks for the help

Abstract Algebra, order of ab is equal to the order of a times the order of b?? Hi! I am working on some problems in abstract algebra and I am stuck at the moment. I hope some of you guys could help me out a little. Homework Statement a and b are two elements in a group G. Assume that...

Homework Statement Assume that u is harmonic everywhere in R^2, and let v(x,y)=\int_0^y u_x'(x,t)dt - \int_0^x u_y'(s,0)ds show that f=u+iv is entire analytic. Homework Equations Maybe Cauchy Riemann: u_x'=v_y' and u_y'=-v_x' The Attempt at a Solution I have only tried to see...

Thanks a lot! I'll try to solve this now, I'll be back if I get stuck. ;)

Homework Statement Hi! I am stuck on an exercise in the complex analysis course. The problem is: "Show that the only analytic functions f that depends on only |z| must be the constant functions." Homework Equations - The Attempt at a Solution I am not sure if I undertand the...

The original function has N-1 zeros on the interval (0,pi). The minimal values for the function is 0. And F->N^2 as x->0 and x->pi Wich means, if there are (N-1) zeros then there is (N-1)-1 = N-2 maximum. So I don't have to calculate the derivative. Thanks for the help ^^