Recent content by Sombrero

Dear PF, I have one question form Peskin Schroeder...could you pls help me It is very simple question... Since I don't know how to write formulas here I put my question in attachment. Thank you very much.

Sorry for bothering... How does righthand side of formula 5.94 is derived from its left handside after some approximation? Probably it is very simple question but I could't get that expression:confused: Thank u very much

Dexter I really appreciate ur quick responses that's really very helpful. Thanks So can I from two sets of generators of fundamental representation of SU(2) (from Pauli Matrices) somehow get Lorentz generators for vector transformation? The generators of a direct product representation...

Dear PF, Just recently I got book (Group Theory of Physics by Wu-Ki Tung), I had a glance through it. I have a question: SU(2)*SU(2) is isomorphic to Lorentz group (Let symbol “*” be a direct product), so to know everything on Lorentz group it is sufficient to be familiar with SU(2). Let...

Dear dextercioby thanks for your reply, Could you advise me some books about this issue? Thank you in advance

Hello everyone, In wikipedia when searching Lorentz representations, there is given that (1/2,0)*(0,1/2) corresponds to Dirac spinor representation and (1/2,1/2) is vector representation, but in P.Ramond's book "Field Theory - A Modern Primer" I read (1/2,0)*(0,1/2)=(1/2,1/2), obviously I...

Not "correct" question... :(

Dear PF, I have very simple question, it is due to my poor understanding of group theory. WhY in antisymmetric 5*5 representation of SU(5) (there are 10 states) one puts quarks and leptons, since having product of two SU(5) fundamental representations we get a composed antisymmetric ten...

Gents I have one question: If I have expresion for amplitude of some process and this amplitude has pole, I say I have particle caryring such features (suppose mass that makes this pole), if I change some parameters in expression for amplitude and if I get another pole, I say in this case...

One help needed please Gents, I am not familiar with physics and that's why my questions may seem stupid for you, but could you pls help me and explain the Idea of formula 7.27 in attached file from Halzen F., Martin A.D. Quarks and leptons. Does not the e_R tends to infinity when M^2 goes to...

Nobody answers? :( and also could anyone answer thread: https://www.physicsforums.com/showthread.php?t=106533 Thank you

When was reading about renormalization I did no understand the main Idea of the last :(:confused: It has been considered photon propagator with virtual pair of electron/pozitron. Takeing that loop integral the M^2 cuttoff is introduced, which tends then to ininifity, M^2 is "sopped up" in...

Dear Gents, I have one question: Can I say that if I I have some currents, charges form these currents (integrals over time components) and these charges form a close algebra of some group SU (N), then I say that the particles sitting in these currents (all possible incoming/outgoing...

Hola everybody, this is my first visit to PF. Can anyone help me please...my question is from QFT textbook phi(x)|0> is creation of particle at position x, being in superposition of momenum states - - - - correct? <0|phi(y) is birth of particle at position y. So if I consider both expressions...