Interaction Definition and 713 Threads

Does anyone have a good derivation of the Electron-Phonon Interaction Hamiltonian? I've found a few in various books (specifically B. Ridley and others that cite him) and on the internet, but all of them seem to skip some non-trivial steps or introduce quantities that I've never encountered...

Hi... Consider a neutrino with a Dirac mass m_\nu and the weak interaction {\cal{L}}=\frac{g}{2 \sqrt{2}} \sum_l[{W_{\mu}^+ \cdot \bar{\psi}_{\nu_l} \gamma^{\mu}(1-\gamma_5)\psi_l + W_{\mu}^- \cdot \bar{\psi}_{l} \gamma^{\mu}(1-\gamma_5)\psi_{\nu_l} }\right{]} + \frac{g}{4...

Hello: I've heard that Yukawa's interaction could explain the nuclear force, but I also heard that the strong nuclear force is explained by QCD, Could you please explain me more about it ? Thanks a Lot

weak "force" this is really just a question about terminology, so I am not expecting any overly complex answers. I am familiar with the weak interaction, but in what sense is this a force? It is unlike anything that we would consider a force.. The only sense in which I can see it being...

Hi: The electromagnetic and weak interactions were unified in what is called the electroweak interaction, but as long as I know they are different classes of interactions, what I mean is that in weak interactions, there are particles that transform in others (like neutron's beta...

Homework Statement Homework Equations U=-uz*B=ml*(e*h/2*m)*B uz=-(2.00232)*(e/2*m)*Sz The Attempt at a Solution I thought this was very simple until I re-read it after solving. In the n=1 state for an electron isn't ml equal to 0? so U=0*stuff = 0 but then part b says is there...

Hello, This is something that's puzzled me for a while, but I haven't been able to find any conclusive answers anywhere. What I'm wondering is, how far would an electron beam (such as that found in a TV) travel in the atmosphere before it lost its kinetic energy or bonded with the air...

dear all, I am eager to read the "Gauge Theories of the Strong and Electroweak Interaction" wriiten by Manfred Böhm,Ansgar Denner,Hans Joos. But in my country, there's no the book. If you have the ebook or know the web sites to download it, please send it to my email(wuleihnu@yeah.net). Thank...

And would the potential be equal in magnitude yet opposite in sign? If you were to approximate a yukawa potential for some baryon and had it "near" its antiparticle, what would the potential look like. The same for a baryon and another baryon but opposite? This would just be like a...

Just wondering whether there's any interaction, where the t-channel is prohibited, only the s-channel ?

Is weak interaction invaraint under CPT Symmetry? Why?

Quote from Organic Chemistry, L.G. Wade, Jr.: "Not all molecular vibrations absorb IR radiation." "One of the component of an electromagnetic wave is E field. This field alternately stretches and compresses a polar bond." "If this alternate stretching compressing of the bond occurs at the...

Homework Statement Consider two dipoles with moments u1 and u2 arranged as in the following diagram. Each dipole is depicted as two charges of equal magnitude separated by a distance d. The centre-to-centre separation of the two dipoles is the distance r. The line joining the two dipole...

Homework Statement (a) Consider a system composed of two electrons with orbital angular momentum quantum numbers l_1 = 4 and l_2 = 2. Give all the possible values of (i) the total orbital angular momentum quantum number L, (ii) the total angular momentum quantum number J. [8] (b) Explain...

Homework Statement Assume that the current flowing into the loop is 0.500A . If the magnitude of the magnetic field is 0.300 T, what is torque , the net torque about the vertical axis of the current loop due to the interaction of the current with the magnetic field? the loop is initially...

If you were to amplitude modulate a laser such the helium-neon with a microwave signal for instance at 10 GHz, and if you were to shine that laser into a tuned 10 GHz resonant cavity, would the modulated laser excite the cavity? That is would the rise and fall of intensity of the laser beam...

Hi guys, Could someone show me how can I evaluate/measure the cross section of gamma+gamma --> electron + positron I'll be thankful for your help

hi ,everyone from the microscopic view, we can simply regard the atom in the mass as a spring, which will be vibrated by the light wave (collided by the photon, could i say that?)and in this way emit some "new" light waves, but whose wavelength is shorter than the incident wave. And it is the...

Two masses A and B are accelerated to a velocity V on close “parallel” paths. They will experience gravity or free-fall toward one another. If I take the limit as mass A and B are reduced to zero and the velocity A and B is accelerated to approach the speed of light, ( I am approaching...

Hey folks, I have a pretty interesting Lagrangian setup: \mathcal{L}=-\frac{1}{4}(\nabla_a u_b -\nabla_b u_a)(\nabla^a u^b -\nabla^b u^a)-\lambda(u_au^a-v^2)-\frac{1}{2}(\partial\phi^2)-\frac{1}{2}m^2\phi^2-\frac{1}{2\mu^2}u^au^b\partial_a\phi\partial_b\phi My term u^a is a spacelike 5...

Hello I attach a question (PDF-file) which I found in an old physics book, I printed the question and re-generated the drawing which were a bit hard to scan. Can anyone answer the attached question, I think I know the answer but I want to be sure. Thanks Lory

Suppose I have n identical quantum mechanical systems \mathcal{H} isolated from each other. It is a postulate of quantum mechanics that the states of this composite system are described by rays in the tensor product space \mathcal{H}^{\otimes n}. If the states are not allowed to interfere...

Hi all, I'm trying to teach myself high energy physics and was wondering if anyone knew a good reference site on calculating cross sections. I'm specifically trying to calculate the cross section for \nu _{\mu} + e^- \rightarrow \mu ^- + \nu_e using the 4-fermi interaction. Are there any good...

Could anybody tell me, if there is anything that can distract magnetic field, but not in the way diamagnetics do. I.E. when I put two magnets on table N|S S|N they will start repulsing themselves, and i want to know, what can i put between them, to avoid reaction of repulsing, so there will be...

Not sure what the technical term for that in but could you inject mice cells (heart, liver etc) into humans without killing/harming the human?

Homework Statement A teenager has a car that accelerates at 3.00 m/s2 and decelerates at -4.50 m/s2. On a trip to the store, he accelerates from rest to 16.5 m/s, drives at a constant speed for 5.00 s, and then comes to a momentary stop at the corner. He then accelerates to 18.0 m/s, drives at...

Homework Statement I have already solved almost all of the following questions.Just want to check them and improve reasoning.So, please do not blame me for asking you to do it for me. Check if the following interactions are possible or forbidden and indicate the interactions when...

Hi all, sorry if this has been asked before but i can't find a thread with the info I'm after. I'm doing an access course at lvl3 (AS/A2) which includes biology and I'm stuck on the following question as part of an assignment I'm to hand in next week. Q: Suggest an explanation for the fact...

In some QFT books it is written that the generating functional Z[J]=\int \mathcal{D}\phi e^{i\int d^{4}x(\mathcal{L}_{o} +V(\phi) +J\phi) } can be expressed in equivalent form: Z[J]=e^{i\int d^{4}xV(\phi)} \int \mathcal{D}\phi e^{i\int d^{4}x(\mathcal{L}_{o} +J\phi )}. The only argument...

Hi, i just need to get together all the conservations/violations that the weak interaction conserves/violates. I know about parity, charge conjugation and basic properties such as charge and lepton number but i was wandering if anybody could think of any more. No mathematics please! Thanks.

What would the concequence of 2 black holes moved to a certain distance appart with one being say double or triple the mass of the other. Would the force (or could the force) be strong enough to warp space back so that it 'destroys' the event horision therefore returning the black hole to...

four fermion interaction?? The four fermion interaction proposed by enrico fermi to learn weak interaction postulates that four dirac fields interact via the interaction hamilton J1^{}u*J2_{}u where J1^{}u=phi_d(x)*y^{}u*phi_c(x) but by question is this is the bilinear form taken...

I have a proton and an antiproton scattering, via a pion exchange. The matrix element has the form: M=g*(\bar{u}_{1}\gamma ^{5}u_{2})\frac {1} {q^2-m^2}( \bar{v}_{1}\gamma ^{5}v_2) Wher g is my coupling constant, and q the 4-momentum of the pion. The problem is that when I compute the...

http://www.wdc.rl.ac.uk/wdcc1/papers/nature.html It would be interesting to find out just what this doubling effects if anything. http://www.wdc.rl.ac.uk/wdcc1/papers/nature.html may be this. http://www.economist.com/world/displaystory.cfm?story_id=9071007 or this?

Homework Statement Is it possible for pair production to occur without interacting mwith matter? Homework Equations E+ + E- = E(gamma) - 2*m_e*c^2 The Attempt at a Solution In the Coulomb field of nucleus (or electron), the incident photon energy can be converted to the...

Is it possible to attract stray ions by aiming a laser upwards into the ionosphere?

I've noticed the metallic package seals on some bottles of isopropyl alcohol and other products tend to flake into the bottle when trying to remove it. This doesn't seem like a good thing. Could the substance used in the seal interact with common skin care ingredients, such as benzoyl peroxide...

Hi, Can someone explain to me why do we actually need the Interaction/Intermediate representation? In my past, each course in QM touched it only for a few minutes and then it got... forgotten. Can someone please give me an example as to how (and when) it is used (and a good reason why)...

What does it mean to say to say that the electroweak interaction is described by a gauge field theory based on the SU(2)_{L}\timesU(1)_Y symmetry group? I know that SU(2) is a group of unitary matrices and U(1) is the circle group but I don't really see what the sentence means. I haven't taken...

Hi, It is generally not my style to ask for this type of help... But I am now summarizing my PhD thesis, and I feel that I desperately need a quote by a famous scientist who say something like that: The whole solid state physics is based on throwing photons on matter and studies of humps...

Let me start by saying I know nothing and just come seeking knowledge. I hear that a graviton has never been discovered, only theorized. True? If so, I was thinking of how we might find one. When planets get nailed by asteroids isn't the energy from the momentum of the asteroid getting...

Hello, I am trying to make a very rough computer model of the clumping of matter into galaxies in the large scale structure of the universe. As a starting point, I'm randomly distributing particles across a rectangle and then letting all the particles (about 22500 particles) interact via the...

All the information is in the attachment. The problem I'm having is that I can't seem to satisfy the equations correctly, and I can't figure out why. Am I doing this right?

I am writing an essay for a course regarding the history and philosophy of science. The topic is: "During the 17th century, there was intense interaction between science and religion. Using examples, mount an argument that takes a position on this interaction. In other words, with reference...

I am trying to find more information on the above subject. Can anyone point me in the right direction? Also: What formula do you use to work out the volume of the material? Any help, greatly appreciated :smile:

There is this characteristic time associated with the decay of particles; ~10^-16s for electromagnetic decay, ~10^-23s for strong decay and >10^-13s for weak decay. Now I know that the decay time is to first order inversely proportional to the coupling constant squared (from a first order...

Hi all, I got asked a question recently which I really should know but wasn't able to answer to my satisfaction. When an x-ray is emitted by an ionizing process, typically an inner electron is ejected and an electron from a higher orbit ``falls'' into its place. In the process an x-ray is...

I was wondering if you excite a inner electron in a multi electron atom to a outer cloud what is the effect on filling the hole. So if you excite a inner electron and it jumps to a open space in the valance/conduction cloud (so it does not leave the atom) in the ~10^9 second of excitement...

Does gravitational waves participate in gravitation interaction?? Does gravitational waves participate in gravitation interaction?? When gravitational waves pass through the sun ,it will deflect?? Thank you in advance!

hi, i used stata to regress these two models, the problem is about gender and wage descrimination and stuff like that. experience and gender are the predictors for salary. so here are the multiple regression results, also gender is a dummy variable with 1 = male and 0 = female: model 1...