Recent content by AdeBlackRune

Homework Statement Let us consider a fully connected Ising model with four-spin interaction in a transverse field Write the mean field Hamiltonian. Homework Equations none The Attempt at a Solution I know that the mean value of the product of two spins is equal, in the thermodynamic limit...

Thanks! So such a defect introduce a non zero reflection amplitude and unlukily it is not the answer i hoped to hear :( The real problem I'm trying to resolve is to physically justify the introduction of a global phase factor in the S-matrix. I hoped that such a defect could help me but, as you...

no one has a little suggestion ç_ç?

Hi, i would ask you an opinion about a (maybe stupid) doubt. Let us think of a 1D lattice whose sites distant from each other "a"; a plane wave in the lattice is given by e^{ikja} where k is the momentum and j an integer label for each site. Now, we modify the lattice in this way: between...

Hi, i'm studing the divergent/convergent behavior of some feynman diagrams that emerge from the study of luttinger liquid. One of this diagrams has a loop inside it and loop-integrals has the following form: \int_{-\Lambda}^{+\Lambda}dQ\int...

Hi, I'm reading ad article of Lal et al (junction of several weakly interaction quantum wires: a renormalization group study). It's quite cleare but there are some row I'm not good to understand. Could someone help me to understand how obtain equation (6) from equation (4)? I don't know how to...

Hi, this is my question: suppose that at time t' our system is in the state | \psi(t')\rangle The probability for the system to be in the state | \phi\rangle at the time t'' is the norm of \langle \phi| \psi(t'')\rangle This in the Schrödinger picture. But how i can write the same thing in...

I suppose that raising or lowering indices leaves unchanged the number of indipendent components, but i was not able to find a confirm of that. I thought that, given the metric tensor, the Rikml are (linear?) functions of the Rrkml component. So, can 20 indipendent quantities generate more than...

Hi, thanks for the attention and excuse for my bad english. I'm studying general relativity and I have a doubt about the number of indipendent component of the riemann curvature tensor. We have two kind of riemann tensor: type (3,1) Rikml type (4,0) Rrkml There are also some symmetry...