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5
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2answers
371 views

Photon pair production at relativistic speeds?

This is probably an obvious question, but I don't see it answered anywhere. Imagine we have an object in the Universe that is traveling, relative to the Milkyway at about .99999999999999999999999999c ...
-1
votes
0answers
13 views

Quarks and pai-production [duplicate]

When Quark, antiuquark pair is created by high energy photons, they glue togheter as mésons or another pair is created to combine they, totalizing four particles? Following QCD both quarks would glue ...
0
votes
1answer
38 views

Quark, antiquark pair doubts [closed]

When Quark, antiuquark pair is created by high energy photons, they glue togheter as mésons or another pair is created to combine they, totalizing four particles?
0
votes
1answer
31 views

Pair production of quarks

I was reading about pair-production of particles by photons, and in every place that I read, only the electron/positron production was said. So I had the following doubt, is it possible to have a ...
0
votes
0answers
13 views

Presence of a nucleus for a photon to produce electron-positron pair

Is the presence of a nucleus always necessary for a gamma-photon to produce electron-positron pair? Is Pair production possible with two photons head on collision, in the absence of nucleus or virtual ...
0
votes
1answer
27 views

Can pair production and recombination make a gamma ray appear to travel slower than the speed of light?

I was reading about pair-instability supernovae, which is when gamma rays produced in the core of a large star become energetic enough to produce electron-positron pairs, which causes a loss of ...
0
votes
0answers
24 views

Pair production in different reference frames

I understand that energy of photons is defined by their wavelength/frequency. This frequency (and so energy) will be different for different observers: observer moving towards the photon will see ...
1
vote
0answers
52 views

Pair Production via Black Hole

I think this should be a straight forward question. Is it possible for a photon to pass near a black hole and be turned into a matter and anti-matter pair according to current theory? Edit: From the ...
0
votes
0answers
20 views

pair production of different families

I know that we have a few different conservation laws. Energy, lepton number, conservation and charge. We also cannot have pair production without the presence of a nucleus, however, in my head, none ...
0
votes
1answer
26 views

How would the Compton Effect be if an electron absorbs 100% of the energy of the incident photon? [duplicate]

How can I prove that the relativistic energy and the impulse cannot be conserved if an electron, which is essentially free, absorbs all the energy of the incident photon?
0
votes
0answers
31 views

Estimate the threshold for $e^+e^-$ production due to the vacuum instability in an atom.

When a nucleus with very high $Z$ is created, the binding energy of the innermost electronic orbit becomes sufficient to create $e^+e^-$ pairs. The pair can be created out of the vacuum – the electron ...
1
vote
2answers
84 views

Why does lead have a higher attenuation coefficient for 5.0 MeV than for 10.0 MeV?

I was doing some calculations on radiation, and I noticed that lead has a higher attenuation coefficient for 5.0 MeV than for 10.0 MeV, namely $1.44 \, \mathrm{cm}^{-1}$ for the former and $1.23 \, \...
1
vote
0answers
30 views

Antimatter transmission [closed]

Well, i am theorizing a new method energy transmission, and need some advice. I have DC current being generated, and wanted to think of a unique solution to transfer electricity without any ...
2
votes
0answers
25 views

Why do mesons like the J/Psi or Y exist? Shouldn't the quark/anti-quark pair annihilate? [duplicate]

q/qbar->photon is part of Drell Yan, so it's kinematically allowed. Is this somehow related to the difference in speed phenomenologically between a strong and a weak decay? As in is this annihilation ...
1
vote
0answers
30 views

Pair production in empty space [duplicate]

Why can't the pair production process occur in empty space? I have read that a nucleus must exist and this is how it is useful: that the photon turns into virtual loops of e+ e- and one of them ...
0
votes
1answer
34 views

momentum conservation in particle-antiparticle creation

It's understood that the PRESENCE of a heavy nucleus is necessary for conservation of linear momentum in pair creation. What I can't understand is why it must occur in ADJACENCY of the nucleus. Is ...
0
votes
2answers
39 views

Pair annihilation - can annihilation be moderated?

I recently asked this question: How close does a particle-antiparticle pair need to be for annihilation to happen? And that received a good answer. But there was a second part to my question that ...
0
votes
0answers
33 views

Do copropagating photon pairs exist?

Countepropagating photon pairs with opposing spin are well known. Are there physical phenomena that produce copropagating photon pairs with opposing spin? Wild speculation: A cooper pair of ...
0
votes
0answers
36 views

How is charge separation in a polarized vacuum possible?

How is Charge Separation in a Polarized Vacuum possible? The Uehling potential provides the first correction term to the classical coulomb potential from QFT vacuum polarization: $$ V(r) \approx -\...
0
votes
1answer
124 views

Are the particle-antiparticle pairs produced in vacuum virtual particles, and can they interact with normal particles?

If it is true that due to energy fluctuations of a vacuum being able to produce a particle-antiparticle pair that shortly annihilate with each other and disappear again, is the following circumstance ...
2
votes
1answer
809 views

Should I observe single/double escape peaks for all energies above 1022 keV

I have already asked a question similar to this, but that question was specifically relating to the case of K-40. I'm going to generalize it to any case My question is to do with the field of gamma ...
3
votes
5answers
343 views

Where does mass come from in pair production?

In pair production, two gamma rays with > .511Mev can come together to create a positron and an electron. So two electromagnetic waves E and B fields, with No mass and No gravity and traveling at ...
4
votes
0answers
57 views

question about Blandford-Znajek original paper

I'm trying to follow the original Blandford-Znajek paper (found here), and I can't find how equations 2.1, 2.2 and 2.3 are obtained: 2.1 refers to "the charge density required to ensure that $E \cdot ...
2
votes
4answers
859 views

Is pair production only with $\gamma$ photons?

in my revision guide the section on pair production only mentions it happening with gamma photons, so the question arose whether this is the only way it can happen? This is what the book says: "Pair ...
0
votes
1answer
78 views

Entangled Photon (laser pointer)

From a laser pointer emission; is it creating entangled pairs of photon? is it possible to get more than "pair" entangled, like group of photons all entangled?
0
votes
1answer
101 views

Pair production with nucleus

I've seen in other questions that pair production is not possible in vacuum, i.e. it needs a nucleus or something massive in order for conservation of momentum to hold. I've seen the derivation of ...
-1
votes
1answer
161 views

Under what conditions would photons interact to create pair production? [closed]

I understand that two photons colliding can result in pair production but under what conditions would this happen? Would the photons have to be in a superconductive state or is it just by chance, as ...
0
votes
2answers
222 views

Pair production and energy conservation?

Consider the question whether a photon can decay, in the free space, into an electron and a positron - a pair production event. Such an event I don't think is possible, because both energy and ...
3
votes
2answers
212 views

Does positron-electron annihilation preserve enough info to reverse exactly

An electron-positron annihilation can produce a pair of gamma rays. In the reverse process, known as pair production, can the gamma rays carry enough information to determine the resulting ...
2
votes
2answers
906 views

Why the photon can't produce electron and positron in space or in vacuum?

$$\frac{hc}{\lambda} = K_e + K_p + 2m_e c^2$$ could be the energy conservation equation for a photon of wavelength $\lambda$ decaying into a electron and positron with kinetic energies $K_e$ and $K_p$ ...
0
votes
1answer
54 views

How can nuclear decay both annihilate and create?

This'll be back to basics for many of you, but here's something I still don't get. How can nuclear decay of an unstable atom both create and annihilate positron-electron pairs? You have an unstable ...
3
votes
1answer
89 views

Can the rate of virtual pair production from vacuum be computed?

Consider for instance the QED Lagrangian. Is it possible to compute the rate of virtual electron-positron creation from the vacuum?
6
votes
3answers
470 views

Is it possible to produce images of pair production in home-made cloud chamber?

There are some nice pictures on the web showing the counter-spiralling paths of an electron positron pair produced in a bubble chamber with a uniform magnetic field, for example:- Would it be ...
1
vote
3answers
156 views

Why don't we consider electrostatic energy of the pair in the case of pair production?

I have seen this Wikipedia article and many others, but in none of them I find any mention of the electro-static energy of the generated pair. Why? I mean, the energy conservation should be written ...
1
vote
2answers
42 views

Space travel using pair production

If the method for creating electrons and positrons from photons, as described in this article, were proven correct, would it be possible to use it for accelerating space ships – using only an energy ...
2
votes
1answer
965 views

Feynman diagram for pair production in matter

I'm aware that electron pair-production from a single photon requires the presence of matter — say some large nucleus — able to absorb momentum, as in the process \begin{align} N \gamma \rightarrow N ...
5
votes
1answer
183 views

$\tau$ pair production question

There's a question on my homework about the process $e^{-} e^{+} \rightarrow \tau^{+} \tau^{-}$. Specifically, it is claimed that the minimum energy required of the colliding positron and electron ...
4
votes
2answers
616 views

Pair production of neutrinos

I learned that neutrinos have a much lower energy than electrons. Pair production of electrons occurs when the photon energy is above 2 times the energy of an electron. So I am wondering if pair ...
0
votes
0answers
125 views

positron / electron annihilation - where is the invariant?

Electron and a positron are headed towards each other with same kinetic energies - observed from center of mass (COM) system. After the colission two photons are emitted and are headed in opposite ...
0
votes
1answer
187 views

Atom emitts a photon - what is the frequency of the energy of the photon?

Lets say I have an atom of known mass who goes from excited state to the ground state whose energy is $14.4 keV$ lower. I know that the emitted energy $14.4keV$ got converted into an energy of a ...
2
votes
2answers
865 views

2 protons collision (both with different kinetic energies) - I don't know what to put in for $p^2c^2$

The problem statement: Two protons with kinetic energies $W_{k1}=4GeV$ and $W_{k2}=2GeV$ colide and form new particles. What is the mass of newly born particles? There are as many as possible ...
-1
votes
1answer
310 views

2 particles collision - deriving the equation for an energy which can become mass of new particles!

Q1: Lets say a particle with mass $m_1$ and kinetic energy $W_k$ colides with a particle of mass $m_2$ at rest. Can anyone explain why do both particless ($m_1$ and $m_2$) plus an aditionall mass $m$ ...
0
votes
0answers
470 views

Pair annihilation - how to generaly solve these types of problems?

Simple question regarding pair production: Can a collision of an electron with a positron result in two photons? I have this problem to solve and I doubt this is even possible. Please provide some ...
-2
votes
1answer
172 views

Conservation of energy issue with pair creation/annihilation

Question: what is the energy balance in this situation? (Fig A) Two gamma rays collided and produced an electron/positron pair $(e-/e+)$. (Fig B) 1. because all particles are accelerating ...
2
votes
0answers
90 views

Pair production intefering with gamma-ray laser black hole fabrication

A common "proposal" to make a micro black hole is to use on the order of 10^12 kg of gamma-ray lasing medium and focus all the light at a small point. However, intense light will interact with itself ...
0
votes
2answers
305 views

Why does Quantum Electrodynamics Allow a Photon to Exist Temporarily as a Positron and an Electron?

In this question... Why does a photon colliding with an atomic nucleus cause pair production? ...I asked why a photon colliding with a atomic nucleus can become an electron and a positron. The ...
8
votes
4answers
4k views

Why does a photon colliding with an atomic nucleus cause pair production?

I understand that the photon needs to have enough energy to produce a lepton and it's antimatter partner, and that all of the properties are conserved, but why does the photon do this in the first ...
20
votes
1answer
454 views

Anomalous target space diffeomorphisms for one-loop world-line integrals

The Schwinger effect can be calculated in the world-line formalism by coupling the particle to the target space potential $A$. My question relates to how this calculation might extend to computing ...
2
votes
2answers
3k views

Pair production - mathematically?

Allover the web i am only seeing a statement similar to this: Pair production is not possible in vaccum, 3rd particle is needed so that conservation of momentum holds. Well noone out of many ...
1
vote
1answer
3k views

Pair production in complete vacuum

I want to prove that pair production (electron-positron) cannot happen in complete vacuum. This is why I obeyed conservation of energy and got equation: $$h \nu = m_e c^2 \Bigl[ \gamma(v_1) + \gamma(...