Interaction Definition and 653 Threads

I have always been told that waves interact with objects with a size similar to their wavelength. For example: if you look at your microwave you notice that there is a grid with a size much smaller than the wavelenght (so that they can not pass over), but visible light can pass very easy because...

Hello During a simulation of light in gamma-scintillator interaction, it seems that there are a lot of Cerenkov photons. I don't know their contribution to the final intensity (it will need a long time to compute it). The textbooks usually say that the gamma ray will produce secondary...

I have a few questions: Can a u quark turn into a d quark (heavier) via the weak interaction? If so, how is the mass/energy shortfall made up? How can the (supermassive) carrier bosons (W, Z) be called into being? Where does the energy come from? Or is the energy bill unpaid because they are...

The strong interaction outside nucleons - what mediates it? Is it gluons? Is it mesons? Is it gluons within mesons? Thank you.

I'm trying to find measurements for the weak interaction at various distances. Any suggests for search terms or relevant paper would be appreciated. Thanks, Dan

Homework Statement I am trying to derive the dipole-dipole interaction derivation, which is: U=(-p1p2/4πϵ_0) (1/z^3) ((2cosθ_1cosθ_2)− (sinθ_1sinθ_2cosζ)) Where p1 and p21 are the two dipole moments, r is the distance between two dipoles on the y axis, θ_1 and θ_2 are the angles between the...

If there are two interaction terms in a single model, does that mess up the interpretation of it? For example, Gender*Weight and Gender*Height. Say the model is Y~Weight+Height +Gender +Gender*Weight+Gender*Height. Would I simply interpret it as usual? That is, "The difference in mean...

Hey all. Since gravitational waves travel at the speed of light, when they are "escaping" from mass, doe's their intensity lower? If so what mass would be needed to completely absorb a gravitational wave given the wave's properties? Any help appreciated.

Reading some of the recent info on black holes and how they ingest gas matter including stellar material... why doesn't dark matter be absorbed into the black hole and according to the article dark matter is part of black hole formation...

Recently i am reading Classical Mechanics from Gregory In section 3.3 , he provide a statement which he named " The law of mutual interaction." as follow "The law of mutual interaction" Suppose that two particles P1 and P2 interact with each other and that P2 induces an instantaneous...

Where is the electron-nucleon interaction? On the surface of the nucleus, or at the origin (R-0) ?

Is there any type interaction between neutron and matter other than strong interaction? When a neutron elastically or inelastically scattered, does the strong interaction still govern the whole process? Thank you!

Say we have a phenomenon where we want to see if x is related to y where x is continuous. Further, there is an opposite effect of x on group 1 compared to group2. Say for group 1, increasing x is associated with increasing y, for group 2, increasing x is associated with decreasing. (this is not...

Edit: Disclaimer, this post contains faulty ideas I'm a 'pedestrian' to physics trying to wrap my mind around various concepts of relativity, and one of those is a visualization of two, say, planets, say each starting at rest. By my understanding, their mass causes space to relatively...

Consider the one loop correction to a 2 -> 4 scattering process in phi4 theory.The only IPI/non snail contributions is that shown in the attachment. I have an automated package that will do all the feynman diagram generation for me and for this process it returns 15 diagrams, which means to say...

Homework Statement A tau neutrino with energy 1GeV interacts with a stationary neutron. Can the neutrino be detected via a charged current interaction? Take the mass of tau to be 1784MeV/c##^2##, 105MeV/c##^2## for the muon and 939MeV/##c^2## for the neutron. Homework EquationsThe Attempt at...

The Higgs boson can be thought of as mediating a "fifth force" that is not a gauge force but a Yukawa interaction. What is the main difference between Yukawa and gauge interaction?

Hello, I know QED and QCD as isolated theories but now I thought about particle interactions with QED and QCD processes (like fpr proton-antiproton scattering). But I'm not sure how to interpret this mathematically. As I understood my Feynman diagrams are nothing more like pictures for the...

Lets suppose that I have a magnetic dipole moment at (0,0,0) pointing to the Z axis, and in the position (X,Y,Z) in the space, I have a Hydrogen atom, I would like to know the exact interaction between the magnetic field created by the magnetic dipole moment in (0,0,0) and the magnetic fields of...

Hello. I have studied about DWBA (distorted wave born approximation). But, I do not know the physical meaning of "DWBA without spin-orbit interaction". I think, I can not understand about meaning of spin-orbit. How can I understand "without spin-orbit intertaction". Thanks.

Homework Statement [/B] Consider two charged particles 1 and 2, each of them able to translate (move from place to place) and to spin.Homework Equations I can not completely think of relevant equations at the moment. The Attempt at a Solution [/B] I am a bit confused on how charged particles...

Hello, From my understanding, the weak interaction only acts of Left-Handed Chiral Particles, and Right-Handed Chiral Anti Particles. There have been observed fermions (other than neutrinos, where all observed neutrinos are Left Handed Chiral) where some are left handed and some are right...

Hi All, My question goes as follows: Suppose that, we charge a conducting very thin spherical shell in 'empty space' with a charge equivalent to 16 electrons. The radius (R) of the shell is 20 light years. We wait 20+ years for the electrons to reach equilibrium. Then, we approach one electron...

I would like to consider the interaction terms in the Standard Model which allow the following decay process: The only interaction terms in the Standard Model which allow this decay process are contained in the charged current interactions: $$\mathcal{L}_{cc} =...

I am reading Cohen-Tannoudji's Atom photon interactions (2004 version), in the Appendix he explains that for atom-light interaction, the electric dipole Hamiltonian (d.E form) is got from the original, "physical" (in line with his language) p.A form Hamiltonian by a time-independent unitary...

Homework Statement I am given the following interaction, $$\pi^-+p\rightarrow \pi^++\pi^-+n,$$ and asked to draw the Feynman (quark flow diagram). Homework Equations None; just baryon number conservation, quark flavor conservation, etc. The Attempt at a Solution First, as baryon number and...

Bhobba said "Decoherence usually requires interaction with something macroscopic and an environment". I assume decoherence still occur to the atoms and molecules inside any object because they are exposed to the thermal vibrations and CMBR. Let's say for sake of discussion we can freeze an...

Hi, My question is that can one interaction term represent two vertices? For instance, can the lagrangian interaction terms L = eψγμψAμ represent a feynman diagram like these: or should there be two terms in the lagrangian to construct such diagrams? Thanks!

Dear all, I'm curious to know how to calculate an interaction. I'm a chemist and I'm not really used to practice Maxwell equations, so I don't have the complete background for that, but I think it may be trivial even for a physicist student. Let's say we have two surfaces, one has a total...

Hi ! I'm not sure to post my question in the right place so I'm sorry if I'm wrong...! I have a particle associated with a certain spectrum in energy S (differential cross section). When the particle interacts I use this distribution to have the energy lost. Now, if my particle interacts 2...

The hydrogen is placed in the external magnetic field: $$ \textbf{B}=\hat{i}B_1 cos(\omega t) + \hat{j} B_2 sin(\omega t) + \hat{k} B_z ,$$ Using the relation ## H = - \frac{e\hbar}{2mc} \mathbf \sigma \cdot \mathbf B ##, then I got the form $$ H = H_0 + H' , $$ where $$ H'= - \frac{e...

Hi everyone, I have the following question When a positive pion interacts with a proton, a kaon can be produced, along with another strange particle, as shown in this equation \pi^++\textrm{P}\longrightarrow \textrm{K}^++\textrm{X} Circle the type of interaction shown...

Homework Statement Suppose that a hypothetical fermion ##\psi## interacts with the Higgs field ##h## obey the Lagrangian $$\bar{\psi}(i\gamma^{\mu}{\partial_{\mu}}-y\nu)\psi-y\bar{\psi}h\psi-y_{\mu}\bar{\psi}_{\mu}h\psi_{\mu} +...

Homework Statement Hello, I'm asked to show the equivalence of the given Hamiltonian below which describes the interaction between an electron and a nucleus and the following Hamiltonian The Attempt at a Solution [/B] I've simply written down each Hamiltonian as a sum of four tensor...

I'm having a hard time understanding the mechanism of J coupling in NMR. Why is coupling information only transmitted through bonding electrons with nonzero s-character? For example, why can't coupling information be transmitted through a bond with no s-character, e.g. a retrodative bond...

The (classical, relativistic) Lagrangian for electrodynamics contains the field energy density -FμνFμν/4 and the interaction term -Aμjμ. I understand the maths of that - for one thing, the equations of motion turn out right if you plug this into the Euler Lagrange equantion. Now I recall having...

Hey everyone, For my studies I have to read a part about approximation methods in Quantum Mechanics. Unfortunately I'm having difficulties understanding some concepts. If I'm correct, for describing a multi fermionic system of n electrons, the Hartree Fock (HF) method uses a Slater determinant...

Homework Statement A(n) 8.5-kg object is sliding across the ice at 2.34 m/s in the positive x direction. An internal explosion occurs, splitting the object into two equal chunks and adding 12 J of kinetic energy to system. The explosive separation takes place over a 0.16-s time interval. Assume...

Homework Statement A 0.70-kg basketball dropped on a hardwood floor rises back up to 66 % of its original height.If the basketball is dropped from a height of 1.4 m , how much energy is dissipated in the first bounce?( answer =3.3J). How much energy is dissipated in the fourth bounce? Homework...

Homework Statement A 0.70-kg basketball dropped on a hardwood floor rises back up to 66 % of its original height. If the basketball is dropped from a height of 1.4 m , how much energy is dissipated in the first bounce? Homework Equations U=mgy The Attempt at a Solution U=(0.70)(9.8)(1.4)...

Homework Statement Find the interaction energy ( ##\epsilon_0 \int \vec{E_1}\cdot\vec{E_2}d\tau##) for two point charges, ##q_1## and ##q_2##, a distance ##a## apart. [Hint: put ##q_1## at the origin and ##q_2## on the z axis; use spherical coordinates, and do the ##r## integral first.]Homework...

Hello everyone. What measurements have been done of the Higgs self-interaction? If nothing has been done yet, what are the relevant groups and research articles describing the progress of work in this direction? If this has been done, I would love to know the references. Thanks!

I am trying to derive the k dot p formula with the spin orbit interaction term included. I am having some trouble. I insert a bloch wave function multiplied with an unspecified spinor. But how do I treat the cross product term that comes from the SO and what is the effect of the pauli matrix...

As I understand it (e.g. from discussions around the Fermi field theory of the nuclear force), a spin 1/2 particle can emit a spin-1 particle and simultaneously flip its spin (say, spin +1/2 -> photon +1 & spin -1/2); but how does this work with spin-2 particles? Does it need to emit pairs in...

Hi all, I've read a number of posts on virtual particles (including one of my own), but I'm still confused about one aspect - the interaction between real and virtual particles. Say we have an electron moving from position A to position B. As the electron moves, there should be virtual...

Hello. Does anyone know a good book explaining light and semiconductor interaction? Namely, the processes that take place inside the material.

Homework Statement [/B] Thin rod of length l is placed with one of its ends at the center O of the (thin circular )ring of radius R as shown (Figure 1), perpendicular to the plane of the ring. The rod is charged with total charge Q that is distrubted along the rod's length with linear charge...

Homework Statement In electromagnetic interactions, the force carrier is the photon, and it interacts with anything which has electric charge. Electric charge can be represented by the integers on a single number line and photons themselves carry no electric charge. (a) In the case of the...

How a potential well is formed? Can mass of a wave creates a potential well?

klotza submitted a new PF Insights post The Interaction of Sound and Light Continue reading the Original PF Insights Post.