Interaction Definition and 653 Threads

Homework Statement Write out: H_{SE}(\left|\right\beta,i_{\beta}\rangle\otimes\left|\right e_{j}\rangle) and exp(-iH_{SE}t)(\left|\right\beta,i_{\beta}\rangle\otimes\left|\right e_{j}\rangle) Where...

This is going to be a very elementary question, but I am having a hard time wrapping my head around it for whatever reason. In static equilibrium, like a book on a table, I have no problem seeing that the force exerted on the table by the book is equal and opposite to the force exerted on the...

I've had trouble understanding how the weak interaction could be field based, like classical gravity, or electromagnetism. My limited understanding of the interaction so far had been that left handed leptons and quarks would have an event spontaneously happen to them (such as decay). I thought...

Please see the diagram attached, I don't understand how my lecturer is resolving the E-field in the perpendicular case. He obtains: E_i = \bold{y} e^{-i\omega(t - \frac{n_1}{c} (-xsin \theta_i - z cos \theta_i))} How has he obtained the (-xsin \theta_i - z cos \theta_i) part from that...

I (moderately) understand the basics of the electromagnetic and weak nuclear forces, but I recently heard of a combined electro-weak theory. It apparently states that two forces are different manifestations of a single force at very high temperatures. Does this mean that the photon...

simple eg: negatively charged van de graaff generator top and a magnet. Put magnet near top. Would the magnetic field push the electrons of the charged surface to the sides and deeper into the metallic top?

I have 2 questions... I was told that the transmutation of Li-7 to Be-8 by proton collisions at energies below the classical barrier verifies the QM description of the weak interaction cross section. Firstly, I found the leap in logic very confusing - does the weak force have a role in...

Hi, Im currently writing a theory section for the W and Z bosons mini thesis type project, I am looking to fully cover the main topics in this area and am wondering if i am missing any or need to re-order things: Overview of elementary particles Symmetry and conservation laws Gauge...

I've seen dozens of examples of well-made games and demonstrations that seem to handle this concept perfectly well, and yet I can't find a documented method to approaching it. Basically, a tire on an incline will begin to roll rather than slide down the slope, but a spinning tire dropped on a...

I wonder about gravitational interaction between two bodies of any shape (not necessarly symmetrical). I would like to predict the motion of their centers of mas if they don't interact with any other bodies. Can I assume that mass of each body is located only in the center and compute the...

Say we have two real fields, R(x,t) and S(x,t), which satisfy the 3-dimensional wave equation. Now let there be an interaction potential between the fields R and S of the form, V = m(R-S)^2. Suppose the "motion" of the fields is either symmetric or anti-symmetric, that is R(x,t) = + or -...

Hi In almost every reference I have found the phonon part of the frohlich electron phonon interaction hamiltonian is given by (b_{q}+b^{\dag}_{-q}) notice the +, where b_{q} is a phonon creation operator and b^{\dag}_{-q})is the destruction operator of a phonon. however in a paper on...

Can an electron traveling near the speed of light knock a proton or neutron out of a nucleus?

Hi again :) I need some help in a not difficult question (I hope). I would like to know how other planets can interfere in the system Earth-Moon - I suppose it is mainly gravitational force acting. However, is this interaction from other planets big enough to cause changes in the route of...

Question concerns the existence of the interaction in boost operator in the instant form of relativistic dynamics. (referring to "Relativistic quantum dynamics" after E.V.Stefanovich, http://arxiv.org/abs/physics/0504062) From the existence of interactions in boosts (e.g., in instant form...

Hi I was reading about interactions. It is about the third law, action and reaction. but, If molecules just act on each other in just automatic ways, then how can things emerge? How does emergence happens? It must be special ways of interaction, not simple interactions but complex...

I have been trying to find out how to calculate a number of things in a system involving liquid and gas. In the attached diagram there is a U-bend with gravity acting down on it. If one side is sealed with a plunger and the other side is filled with a fluid (L) we would end up with the...

If you fire energetic ionising particles, like electrons or protons, at a stationary target, the important interactions are ionisation, nuclear reactions and scattering. But if the incoming particles are traveling at high speed, will they not generate a high magnetic field? Why is such a...

Hi all: One system consists of two neutrons. both spin magnetic moments are 1/2. At a instant time, neutron 1 locates position 1 and neutron 2 is in position. As we know, spin magnetic moment is kind of dipole moment. They can generate magnetic field (not electric field). The interaction can be...

I really don't get the difference between the two. What is the difference between Inertia and Interaction? Cite examples. Homework Equations The Attempt at a Solution

Is there a minimum time interval for two fundamental particles to interact, or is the interaction instantaneous? For example, if a photon excites an electron, is there a time period required for this interaction to take place? When a billiard ball hits another one there is obviously a time...

The electron-lattice interaction potential is given by V(r)=\sum_{i} Q_{i}\nabla V_{ei} \left( r- R_i\right) where i is a summation over lattice sites, Q_i is the lattice site displacement, and V_{ei} is the coulombic interaction Now According to Mahan's book Many particle physics...

I(\vec{n}-\vec{m})=\frac{1}{N}\sum_{\vec{k}}I(\vec{k})e^{i\vec{k}(\vec{n}-\vec{m})} I(\vec{n}-\vec{m})=\frac{1}{\sqrt{N}}\sum_{\vec{k}}I(\vec{k})e^{i\vec{k}(\vec{n}-\vec{m})} In which cases is better to use first and in which second relation? N is number of knottes of lattice. And when I can...

Hi, I've got a strange doubt.I model an elastic diaghfram that move water in piping system (a simple pump) so I've got used the 3D FSI multiphicis. Note that in Comsol's examples is the fluid that move the solid structure: i use the same procedure but for the opposite case. I create a simple...

I have just read a book. It said that: "if symmetry is exact, interaction is a long range". Could you explain me more detailed? Thanks!

I would like to understand more about refraction phenomenum from the point of view of interaction of photons with matter. I know that refraction phenomenum can be explained by change of speed of light when it passes through a transparent material medium. We are accustomed to study interaction of...

Gluon is massless particle ,why strong interaction is short-range force?

As we know:Gravitation is attractive force, electric force is attractive and repulsive force. Weak and strong interaction are attractive or repulsive force?

There are 2 identical rods of mass "m" and length "l" separated by a distance "l" in such a way that the 2 rods are in a straight line. Find the Gravitational force between these two rods. Homework Equations The Attempt at a Solution I'm unable to analyse a...

Hi In the case of a moving ramp/oscillating flap at supersonic speeds(m=2.8-3), we get a shock wave boundary layer interaction which is although mentioned in most research papers but no solid literary piece is found on it.( as i checked out) Can anyone help me in this direction? Something to...

Can someone explain how one derives the 4-point Fermi interaction from the full Standard Model? I understand you set up a cutoff \Lambda, and the cost of this is that the coefficients of all terms in your Lagrangian become functions of this cutoff, and you also have an infinite number of new...

the strong interaction's range is 10-15m, but because gluons are massless shouldn't it be infinite? is it something to do w/ confinement?

(correct me if i state anything wrong) the weak interaction only works on left handed particles and right handed antiparticles; so if there was a right handed muon what would it decay into? and is it possible for a left handed particle to become a right handed particle? (not just a change of...

Hi. in my notes the interaction energy is simply stated as being W=\int dV \rho(\vec{r}) \phi_{ext}(\vec{r}) however no explanation is given as to where this comes from. is it simply a fact or should i be able toderive this from somewhere?

--- THREE MAGNETS (N-dipole-body problem) --- imagine 3 bar magnets sitting on a table randomly spaced. they are fixed and can not translate, only rotate around their centers , it is 2D situation. there is no gravity, no friction and only forces are magnetic forces. here is a picture where "x"...

I am having some difficulty understanding the concept of colour charge. I realize that protons and neutrons are made up of a different number of quarks, and this is how they have the charges +1 and zero. I then realized that different quarks have color charge and that in a hadron (protons...

I have a simple question. Are EMR(electromagnetic radiation) waves deflected/affected by magnetic fields or charged particles? I think don't EMR is deflected by either, because radiation is not affected by either magnetic of electric fields. Am I right?

hello. I'm studying a project on Thz radiation and have to establish what material would make a good THz detector. To this end I've tried to find equations linking the aborption of THz radiation in matter and how the absorption varies with wavelength (one of the things I'd like to...

I am trying to find a clear description of what makes the convergence of the error in electronic energy with respect to orbital basis set less rapid in CI calculations than in HF calculations. Can anyone help to find the reason?

It is often stated that the transition amplitude between eigenstates of the free-field Hamiltonian H_0 is encoded by the S-matrix, defined by \langle \mathrm{f} | U{_\mathrm{I}} (\infty,-\infty)|\mathrm{i} \rangle. where U_{\mathrm{I}} is the time-evolution operator in the interaction...

Hello, Im trying to find out if, since an electron positron pair can anhillate to produce a muon-anti muon pair by the weak interaction, can the same thing occur for the production of an electron/anti-electron pair? Or would it just happen by the electromagnetic force? Or both, with the weak...

I'd like to know some informations about the interaction between carbon atomes and aluminum oxide. is there a strong interactio? a low interaction? thanks

Since a neutron has no charge and an electron is not involved in the strong nuclear force, does this mean that an electron has no interaction between a neutron? As in a very dense neutron star, would we expect that electrons could easily pass right though without being absorbed/deflected in any way?

I have measurements of some response of a gene, and two factors: the gene, g=1...G and whether the patient/subject has a certain disease, t=1,2. the full model is y_{gtk}=\mu+\alpha_g+\beta_t +(\alpha\beta)_{gt}+\epsilon_{gtk} I know that to see if genes have any connection at all...

Homework Statement When is Zeeman effect interaction 0? Homework Equations The Attempt at a Solution I was thinking that when l=0, then Zeeman effect interaction should be 0 because when l =0, we only have ml = 0. So, zeeman effect interaction should be zero. I haven't...

One of the core concepts in electric field theory is that charges exert a force on one another: a positive charge "pushes out," and a negative charges "pulls in." What is the mechanism by which charges interact with one another? How does one charge "feel" the presence of another?

Hi all I just have some questions about atom-laser interaction. Suppose that you have single two-level atom interacting with standing wave laser field with specific polarization. my questions are : How many dipole transition moment vectors can the system of a two-level have? How...

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