Recent content by WarnK

Take two identical of those nice NASA space shuttles and at the same time as you launch one you drop the other from its orbit around earth. What happens first? Do the one going up reach orbit before the one falling hits the ground? There's a nice little thread about the shuttles acceleration...

Hi! I want to find the Fourier transform of \int_{-\infty}^t f(s-t)g(s) ds . The FT \int_{-\infty}^t h(s) ds \rightarrow H(\omega)/i\omega + \pi H(0) \delta(\omega) is found in lots of textbooks. So if I let h(s) = f(s-t)g(s), I need to find the FT of h(s) H(\omega) =...

I read on http://cern-discoveries.web.cern.ch/cern-discoveries/Courier/HeavyLight/Heavylight.html that to find the W and Z bosons they used beams with 270 GeV of energy per beam. But the W and Z bosons have a mass of about 80/90 GeV, how come so high-energy beams was needed?

Assumeing F(x) = -V_x and makeing an ansatz P(x,v) = C_1 exp(C_2 x + C_3 V(x) + C_4 v + C_5 v^2) I get these conditions on the constants C_i (2BC_5+A)C_5=0 (4BC_5+A)C_4-C_2+(C_3+2C_5)F(x)=0 (BC_4-F(x))C_4+2BC_5=0 in the second eq we can put C_3=-2C_5 and get rid of F(x) there, but it's...

Homework Statement Homework Equations Find a solution to the PDE B P_{vv} - v P_x + (A v - F(x)) P_v + A P = 0 where A and B are constants, P = P(x,v) The Attempt at a Solution I have no idea how to even guess a solution to this.

<0|T\big( -i\int d^4x \frac{\lambda}{4!}\phi(x)^4 \big)|0> is only one kind of diagram; a disconnected one with no external legs. And that doesn't contribute to any scattering?

Homework Statement Compute the S-operator to first order in the coupling constant lambda. Homework Equations The given Lagrangian density is L = : \frac{1}{2} (\partial_{\mu} \phi)^2 - \frac{1}{2}m^2\phi^2 + \frac{1}{2}\frac{\lambda}{4!}\phi^4 : where phi is a scalar field. The...

So a lorentz transformation from the lab frame to the CM frame would be \left[ \begin{array}{cccc} \gamma & -\beta \gamma & 0 & 0 \\ -\beta \gamma & \gamma & 0 & 0 \\ 0 & 0 & 1 & 0 \\ 0 & 0 & 0 & 1 \end{array} \right] with \beta = ||\vec{u_{CM}}|| and \gamma = (1-\beta^2)^{-1/2} ? It...

Anyone?

Which Lorentz transformation takes the lab system to the CM system? Lab system: p_a = (E^{lab}_a, \vec{p}_a) and p_b = (m_b, \vec{0}) CM system: p_a = (E^{CM}_a, \vec{p}) and p_b = (E^{CM}_b, -\vec{p}) For a binary reaction a+b->c+d, the textbooks I have say quite a lot about the...

If the particle number increases, the sums might have a few more terms, how does that reduce the number of particles?

Homework Statement Homework Equations (this is ~Fetter & Walecka Quantum theory of many-particle systems problem 1.2b) Homogeneous system of spin 1/2 particles, potential V. Expectation value of Hamiltonian in the non interacting ground state is E^{(0)} + E^{(1)} = 2 \sum_k^{k_F} \frac{\hbar^2...

Homework Statement Homework Equations Show that the KG propagator G_F (x) = \int \frac{d^4p}{(2\pi)^4} e^{-ip.x} \frac{1}{p^2-m^2+i\epsilon} satsify (\square + m^2) G_F (x) = -\delta(x) The Attempt at a Solution I get (\square + m^2) G_F (x) = - \int \frac{d^4p}{(2\pi)^4} (p^2-m^2)...

I'm not going to give up on this! The question asks to calculate the mean position of the particle, so if I do that: <x> = \sqrt{\frac{\hbar}{2m\omega}}<n|a^{\dagger}+a|n> = 0 That's just zero, haveing nothing to do with energy eigernstates or size of a? Sure I could calculate the...

Noone have any ideas on this?