# Recent content by noamriemer

Thank you!
2. ### What is the meaning of a basis?

Hi! There is a concept I don't understand and would love to have is cleared... What is the meaning of a lattice with a basis? What do I need it for? Say I have a honeycomb structure. (fig 1) and a basis as mentioned there (did I understand it right? is it the basis? ) why does it become...
3. ### Transistor circut analysis

Thank you both for your great help!
4. ### Transistor circut analysis

Hi there! I'm having trouble understanding the transistor circuit analysis. Hope you could help me :) First I need to find the active region of the transistor. What I saw in the solutions was an assumption that the transistor is in saturation region and then: VBB=IbRb+Vbe+IeRe...
5. ### Mathematica Mathematica help

Hi! I hope this is the right forum... I am having trouble with Mathematica: Maybe someone could help out of his experience ? I created w[x]:=RandomReal[NormalDistribution[0,1],x] I got it's plot. Now I want to integrate it: I wish to receive another graph, which is the plot of the...
6. ### Notation problem

I will take advantage of your kindness and ask another thing: For m^2<0: W^\mu=\frac {1} {2} \varepsilon^{\alpha\beta\gamma\delta}M_{\beta\alpha} p out of it we will get both L's and K's, meaning the algebra is not close in su2. so, there is no finite way to write the states you can get...
7. ### Notation problem

Thank you so much for a wonderful reply!
8. ### Notation problem

I don't know... an adjoint term maybe?
9. ### Notation problem

Hi! I can't understand something in field theory and need your assistance: I wish to understand why a particle of mass m^2<0 can't exist. For a massive particle, in its reference frame, one would write: p_\mu=(m,0,0,0). I understand that. But for m=0, why is: p_\mu=(p,0,0,p) And for m^2<0...
10. ### Understanding definitions

Thank you! But why does p_{\mu}=(0,0,0,m) relate to m^2<0? And likewise, p_{\mu}=(p,0,0,p) relate to m=0? I understand why p_{\mu}=(m,0,0,0) relate to massive particle, My logic here is p_0=E and E\approx m and \vec{p}=0 (because we are looking at the reference frame) But...
11. ### Understanding definitions

Hi guys! There is something I would like to get your help with... I am looking at the equation: W^{\mu}=-\frac{1}{2} \varepsilon^{\mu\nu\lambda\sigma}M_{\nu\lambda}p_{\sigma} Which is, if I understand correctly,a Casimir Operator. Now, I wish to look at a particle in its rest reference...
12. ### Commutators, etc.

I will never get used to this type of writing.... and to think it was invented to make things simpler... I'd rather just write the whole thing. I am sorry but there is something I fail to understand. What are the relations between M_{\alpha\beta} and M^{\alpha\beta}? Why can't I switch the...
13. ### Commutators, etc.

Oh... then there's a problem here... what do I do when I am given M_{\alpha\beta} and what I need is M^{\alpha\beta}? I have an exercise in which I have to prove that : [M^{\alpha\beta},P^{\gamma}]=0 and I need to use M_{\alpha\beta}
14. ### Commutators, etc.

Is it correct to write: M_{\beta\alpha}=g_{\alpha\alpha}g_{\beta\beta}M^{\alpha\beta}
15. ### Commutators, etc.

Wow... thank you so much for this wonderful reply...I am still trying to understand the whole thing... :)