Recent content by jennyjones

Homework Statement I am making an old exam of a particle physics course, and i know how to calculate the cross section for example for bhabha or moller scattering. now one of the questions on the old exam is: Explain why e-+ e+ -> γ is zero, but i am not sure why this is, can someone explain...

thanx!

can some tell me why the second line follows from the first in the attachment thank you

So the function is analytic in a domain if it is differentiable at all points of the domain.

(z*) is the complex conjugate If i look at the Lim (z->0) z/z* i would say that it does not exist because if i look let z approach 0 on the real axis i get 1, and if i let z approach 0 on the imaginary axis i get -1. but now i think i have to look at the lim(z->0) z^n/(z*)^m and am not...

Homework Statement I have to proof for a homework assignment that f(z) = z^(n)(z*)^(-m) where n, m ≥ 1 (are natural numbers) is in no point analytic. Homework Equations binomial function The Attempt at a Solution I found this wikipedia page, were they state that: a...

thanks so much for the help! i think i know how to solve the problem now! F = dp/dt = - h/λτ F = - 6.6* 10 ^-34/(589 * 10^-9 * 16 * 10^-9) = -7 * 10^-20 a = F/m = -7 *10^-20/ 3.8 * 10^-26 kg = -1.8 *10^6

Homework Statement I want to calculate the average force and acceleration on an sodium atom, if a laser bundle shines on it which has I>>>> I(sat). I(sat) is the saturation intensity of the 589nm 3s-3p transition in sodium. 3p lives 16 ns Homework Equations c = 3 * 10 ^ 8 m...

Can someone maybe explain me(or has a good link to a page where this is explained) why scattering in perpendicular direction is suppressed by destructive interference for large particles. i'm trying to understand mie and rayleigh scattering and don't really get why there is no scattering in...

yes, i know but the problem is that i still don't really get why the sky is paler near the horizon! i don't see how a thicker layer of atmosphere makes the light appear white. then light has to travel longer trough the atmosphere, so the blue light is almost scattered out, and red and green...

thanx, but why then does it appear reddish?

I think i get this problem: if the sun is going down it has to pass trough a thicker layer of atmosphere. The blue light is almost scattered 'out' when it reaches our eyes, while the green and the red are not yet. The most red is left(longest wavelength), so the sky appears reddish. (a mix of...

i would think that this would make the sky appear more reddish, since less blue is reaching your eye

sure i have this is something i found As you look closer to the horizon, the sky appears much paler in color. To reach you, the scattered blue light must pass through more air. Some of it gets scattered away again in other directions. Less blue light reaches your eyes. The color of the sky...

I was practicing for my upcoming optics exams, by making an old exam. And got stuck on some problems that seem so silly. 1. Why is the sky blue? My answer: To answer this problem I first need to mention Rayleigh Scattering, a form of scattering which has a very large wavelength...