Particles Definition and 1000 Threads

One of the important predictions of relativity theory is that particles with mass can't reach speed of light in vacuum and will always be slightly slower. I wanted to know more about the maximum speed which can be reached by particles with mass and looked for relevant experiments. But to my...

I have two questions, but the second is only worth asking if the answer to the first is yes: Are the spin matrices for three particles, with the same spin, σ ⊗ I ⊗ I, I ⊗ σ ⊗ I and I ⊗ I ⊗ σ for particles 1, 2 and 3 respectively, where σ is the spin matrix for a single one of the particles? I...

I'm reading a paper these days, How can I get 2.28? It seems for a D-dim SO(2) gauge field, we have spin2, spin1, as well as spin0 particles?

Hi, I have learned about how to find the 4 spin states of 2 spin 1/2 particles, and how to find them by using the lowering operator twice on |1/2, 1/2> to find the triplet, then simply finding the orthogonal singlet state, |0, 0>. I started to attempt finding the states of 3 spin 1/2...

I was thinking about the double slit experiment and I know that if you let electrons go through one slit on the other it'll produce a pattern like a particle and if you let it go through both it'll act like a wave. I also know that if you observe the electron at the hole, the ones you observe...

I'm interested in learning about standard model, and particles. What's a good book to learn from? I have taken some college physics classes. Thanks!

Assuming no interactions, and the energy levels ##\epsilon_j## for a single particle state, the occupation number for this state for a system of particles is given by: à ##n_j=\frac{1}{exp(\frac{\epsilon_j-µ}{kT}) - 1}## (1) (Here comes argument 1) We conclude that the maximal value that µ...

Hello everybody, I have a new thread to post,it is very important to find a solution for this : -Imagine a box full of air particles.The particles are forced to move to a point A on the edge of the box.My question is now,how can I mathematicly describe the movement of these particles toward...

what might be the speed of subatomic particles ? The problem arises from all the interactions of subatomic particles are known to be super fast . thus wish to know how fast they are . Does time have anything to do with subatomic particles ? ( Relativity ) " am a science enthusiast just out of...

Homework Statement So I'm given a spin 1/2 particle in a rotating magnetic field in the (x,y) direction and a constant field, B_0, in the z direction and am asked to find the S matrix describing it. Given is: B(t) = [B_1 \cos(\omega t), B_1 \sin(\omega t), B_0] Homework Equations H = \sum...

i found that in the 3 W-W exchange of 4-fermion interaction of weak decay of Neturon beta-decay process and also this happens in scattering process,is there will be a gap or a channel between two particles?

I've got a question for you all. if there is a wave-function for a single particle, such as a photon.. and there is a wave-function for an electron.. "A wave function in quantum mechanics describes the quantum state of an isolated system of one or more particles. There is one wave function...

If particles at the LHC are traveling very near the speed of light, are they affected by the slowness of time? Also, how can they travel near the speed of light when the planet is rotating around the sun and the solar system is traveling around the galaxy and the galaxy is moving through space...

U(x,y,z,t)*ψ(x,y,z,t)-(ħ/(2*m))*(d2ψ(x,y,z,t)/dx2+d2ψ(x,y,z,t)/dy2+d2ψ(x,y,z,t)/dz2)=ħ*i*dψ(x,y,z,t)/dt qproton=-qe Schrödinger equation for electron in hydrogen atom (if we consider proton as point charge which is moving at a constant speed vproton→=(vp;x;vp;y;vp;z).) is...

The definition of orbital angular momentum, whether for classical mechanics or for quantum mechanical operators, is rxp. Technically, according to this definition, one particle can possesses orbital angular momentum - in this case about the origin. But I cannot think of any examples, in...

I know there are some threads discussing about the Lorentz force equation but this is something different I came across and I couldn't find anyway to derive that formula. To be specific I'm talking about a charged particles in a magnetic field, where F=vqB and everything that is moving has...

I f a particle starts moving with the velocity of light it becomes massless.But practically a massless particle has no existence.Again one of the main constituents of light is photon,then is it a massless particle?But I know electron has the least mass in this world and photon is heavier than...

I know the solution for R2. That is a for an infinite plane you can have one of 2 things (from the classification of 2D surfaces): 1) cross cap (cut a circle out of the plane and identify opposite points). 2) a oriented handle (cut two circles out and identify points on one with reflected...

may i ask you something? if there is any wrong excuse me. according to mass-energy equation mass &energy are not different but two forms of the same. photon ,graviton... are the mass less particles but photon is a form of energy. can you explain why photon is massless?

Homework Statement An unstable ion of mass ##M##, energy ##E## emits a massless particle of energy ##E_\nu## at angle ##\theta##. In the rest frame of the ion, find ##E_\nu^*## and ##cos \theta^*##. Ions are now accelerated to ##\gamma=100## and a detector with radius ##r=20m## is placed...

I was recently reading a PF thread that was questioning the meaning of zero dimensional fundamental "point" particles and virtual particles, and it raised a question in my mind. It's been my impression from previous discussions that most physicists don't really think of fundamental particles...

How does a subatomic particle that has a mass propagate through the steel container of a bubble chamber? Wouldn't this require that the subatomic beam melt the steel enclosure of the bubble chamber and produce a hole so that the subatomic particle, that have a mass, can enter the bubble chamber...

It's easy to find references which explain that the photon is the force carrying particle for the electromagnetic force (ie https://en.wikipedia.org/wiki/Force_carrier). Similarly there are force carrying particles for other forces, like W and Z bosons carry the weak force. This has always...

Homework Statement Assume that a ball of charged particles has a uniformly distributed negative charge density except for a narrow radial tunnel through its center, from the surface on one side to the surface on the opposite side. Also assume that we can position a proton anywhere along the...

Dear PF Forum, I'm just curious about these things. From what I read, the number of atoms in the universe is 1080 Hydrogen atoms. And neutrino is a billion times more. 1.2 x 1089 But what it said is actually the number of protons + neutrons, right? And about this. Is the number of protons and...

Hi guys i don't know much about physics but I am interested in learning about it i have According to wikipedia virtual particle hasnt never been observed but i think that they are wrong it has been observed in this experiment...

Hello, I wanted to study the behaviour of electrons in a spatially bounded system. I want to have a larger number of electrons, but I took 3 to start with and arrived at this system of coupled equations: \begin{align}\begin{bmatrix} \mathbf{\ddot{x_{1}}}\\ \\ \mathbf{\ddot{x_{2}}}\\ \\...

A mica window is used on Geiger counters. The thin mica is supposedly very transparent to alphas. But are there other materials? Extremely thin metal foils?

I visited Chernobyl recently with a tourist company, having read that the radiation levels that I would be exposed to were okay for a limited amount of time. I learned on the trip however, that the greatest risk consisted in getting contaminated particles in your body. The guide took us around...

1. The problem statement, all variables and given/known data Show that the probability density as a function of seperation, r, of two atoms interacting via a potential U(r) (e.g. a function of separation only, such as a Coulombic interaction), is given by $$\rho(r) = Cr^2e^{-\beta U(r)}$$...

I hope somebody is familiar with the discussion on the identical particles in Quantum Mechanics by L. Ballentine. In particular can someone help me explain how the author derive equation (17.44) from (17.41). In case your edition is different from mine, equation (17.44) is the one which looks...

In class I learn that we can get the dispersion relation for particles by using E=hbar*w and p=hbar*k. The calculated phase velocity is w/k = hbar*k/2m, while the group velocity is dw/dk=hbar*k/m. All these make sense to me, except one thing: I always thought that E=hbar*w=hf is only applicable...

I was just wondering, when particles interact with a force (which would be all the time) , does it cause the wave function to collapse? If so does that mean particles interact with forces in small time periods, since we know particles exist as a probability function? I just assumed that fields...

Take some unstable particle species, and put two of them into an exotic atom or exotic molecule, such that the two bound particles fully occupy a 1s orbital. For example, two negative muons orbiting an alpha particle, or two mesons orbiting a massive baryon. Decay of either orbiting particle...

Homework Statement So first the task: Determine the average value of the kinetic energy of the particles of an ideal gas at 0.0 C and at 100 C (b) What is the kinetic energy per mole of an Ideal gas at these temperatures. I took the above right out of the pdf we got from our professor. I know...

The title says it all. For example can an anti-neutron annihilate with an electron? Thanks, Chris

It came to me just now that because we can always take the Fourier transform of a well-behaved function, this means we can think of any such state as a superposition of free-particle momentum eigenstates. E.g., the Hermite polynomial eigenfunctions of the harmonic oscillator. They have a...

Hello. Sorry if my question sounds somewhat weird (I'm a mathematician, not a physicist). I am trying to understand something for my work. I would like to know what is your opinion about it. Assume that there are two electrodes inside a vacuum tube, with a difference of potential between them...

Protons are in very close proximity with each other in a nucleus. This means there is constant electromagnetic interaction, of which the exchange particle is a photon. What determines the wavelength of this exchange photon? How do they exist in the nucleus: constantly being emitted, or staying...

I was reading in Griffit's "Introduction to Elementary Particles" when I stumbled over the following Remark in chapter 4.4.3.1. CP eigenstates are constructed by |K_1> = \frac{1}{\sqrt{2}}(|K^0> - |\bar{K^0}) |K_2> = \frac{1}{\sqrt{2}}(|K^0> + |\bar{K^0}) and, assuming CP conservation...

We know that there are 4 foundamental forces and that they work thanks to mediating particles: Electromagnetic= Photon Weak= W & Z Bosons Strong= Gluons Gravitational= (Graviton)? My question is: If the electromagnetic field and unlimited range and a particle interacts with another even if they...

Homework Statement Homework Equations The Attempt at a Solution a) For this part, I know for distinguishable particles, the expectation value of the square distance $$\langle (x_{1}^{2} - x_{2}^{2}) \rangle = \langle x^{2} \rangle_{2} + \langle x^{2} \rangle_{3} - 2 \langle x \rangle_{2}...

The speed of light is a parameter that attaches itself to what exactly, an inertial frame of reference or a massless particle moving therein?IH

Theoretically are all particles subject to gravity. Or is there any particle which need not be affected by gravity.

Are quarks really considered fundamental particles that cannot be divided further? If an up quark can transmute to a down quark and release a W+ boson which decays to a positron and a neutrino (for example) - doesn't this mean that there is substructure to a quark? What exactly is it that makes...

Homework Statement So I have this practice problem with the solution, but I don't understand how: "A particle of mass m1 and speed v1 in the +x direction collides with another particle of mass m2. Mass m2 is at rest before the collision occurs, thus v2 = 0. After the collision, the particles...

Why is it not possible for a particle to be neither symmetric nor antisymetric on exchange? If a particle can have 1/2 integer spin why can't it have 1/3 , 1/4 etc. I know it's a weird question to ask but I've been wondering about it for a while.

from a malayalam language newspaper i read about Higgsboson that is according to standard model the Higgsboson is the piece of the atom that endows all the other piece with their mass. when electrons,quarks,etc are associated with higgs field they get mass. the light particle called photons have...

I understand that slower particles will be subject to the electric fields of the material for longer and lose energy, but why should relativistic particles also lose energy quickly? The only idea we have is that there is a lorentz contraction of the electric field, BUT why then would that...

Hi there, In the decay of ## B \to D^* l \nu ##, I found that the polarization vectors are described as following: In the B rest frame the helicity basis ## \bar{\epsilon}(0)= \frac{1}{\sqrt{q^2}} (p_{D^*},0,0,-q_0), \\ \bar{\epsilon}(\pm)=\pm \frac{1}{\sqrt{2}} (0,\pm 1,- i,0), \\...