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Questions tagged [pair-production]

Pair production is the creation of an elementary particle and its antiparticle out of a neutral boson, typically a photon, but sometimes a gluon.

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Could a single gamma ray photon break the Schwinger limit? If so, at what energy?

Is it possible for a ray of light, or even a single photon, to 'break' the vacuum of space? If so, at what energies (in eV, e.g.) would this happen?
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Is the matter-antimatter asymmetry a logical or a statistical problem?

When I read on Wikipedia about Big Bang (Inflation and Baryogenesis), I got the impression that in the beginning of the universe all matter and antimatter had been created exclusively as pairs: ...
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Average momentum of particle/anti-particle pairs

I'm far from an expert in physics, I've gathered bits from wiki, books and educational videos. So I apologize in advance if my question is not well framed or plain stupid. It's about particle / anti-...
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Hawking radiation: what does a new external particle have to do with the mass of the black hole?

This question has been asked a few times here in a few different ways but the answers don't quite seem to land for me. Considering the virtual particle pair; one falls in, one escapes, both become ...
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If matter cannot be created or destroyed, how were scientists able to "create" matter out of light? [duplicate]

It has been proven that scientists are able to "create" (using quotations because I do not understand if it is creating or not) matter from light in a particle collidor. How is this possible ...
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Would pair production be affected by general relativity?

Given that during pair production a very small amount of energy from the photon becomes gravitational potential energy in the particles, I was curious how this would be affected by general relativity? ...
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Will the interference pattern still be observed with gamma rays in double slit experiment?

I am little confused. Please correct me if I am wrong. Gamma rays can produce electron and positron pair if they interact with atoms. In the double slit experiment the final screen where interference ...
SacrificialEquation's user avatar
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Differences between 1+1D & 3+1D (background) electric field?

in Sidney Coleman's paper More about massive Schwinger model (PDF). Section 2 "The origin of $\theta$" P.242 (beneath the eq. 2.5). Discuss about some differences between 1+1D & 3+1D ...
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Why Do 137 Electron-Positron Pairs In Their Compton Wavelength Have Electrostatic Potential About Equal The Mass Energy of One Pair?

Why does taking the ratio of the mass energy of an electron positron pair to their electrostatic potential energy at their Compton wavelength yield a number very close to $\alpha^{-1} \approx 137$: $$...
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Why negative energy particles not created near a black hole? [duplicate]

If you take empty space right next to a black hole once in awhile, you will get a positive particle being admitted in the opposite direction of the black hole. In the creation of the photon this ...
Christopher Cuddy's user avatar
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Why isn’t electric potential energy involved in the calculation of pair production?

When I learned about energy conservation in pair production, we only considered the energy of matter and light. Why isn’t the electric potential involved? Also why isn’t the gravitational potential ...
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Causal expansion of EM fields

When an electron and positron are created at the same time and location, is it correct to say that the electromagnetic field due to the two particles is zero when $r>ct$?
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Unitarity of time-evolution operator of Dirac's equation

Let $\Psi(t)$ be state of Dirac's electron in context of Dirac's equation and consider time-evolution operator $$\Psi(t) = U(t)\Psi(0)$$ is or is not $U$ an unitary (preserving length) operator? (note ...
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Pair Annihilation

Why is Pair Annihilation possible in vacuum but pair production needs a vacuum or a 3rd material to conserve energy and momentum at the same time.
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How exactly does Hawking radiation occur? [duplicate]

I understand some parts of the theory, I've read from here https://phys.libretexts.org/Bookshelves/Astronomy__Cosmology/Supplemental_Modules_(Astronomy_and_Cosmology)/Cosmology/Carlip/...
Leon Raj's user avatar
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Why is there no electron-positron plasma around proton?

When electric field approaches Schwinger limit: $$ E_{cr}=\frac{m_e^2c^3}{e\hbar}\approx 1.32\times10^{18}~\text{V/m}, $$ in the presence of such field electron-positron pairs will be spontaneously ...
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Cross-section of pair creation via vitual photons not positive definite

Consider the process of pair creation via two virtual photons, i.e. $\gamma^*(k_1)+\gamma^*(k_2) \rightarrow l^-(p_1)+l^+(p_2)$, where the dilepton (or any other fermions) can be massless or massive, ...
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Negative energy particle effect on observable object

A recent paper "Gravitational Pair Production and Black Hole Evaporation" (discussed in short here) says that any spacetime curvature would produce Hawking radiation, no need for event ...
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Energy of an x-ray generated by cathode ray

I'm trying to understand if I could capture the event of generation of an electron positron pair from a gamma ray inside a cloud chamber. So far I've been thinking of using a cathode ray tube as a ...
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Pair production and observation of high energy photons

Pair production occurs when a photon with sufficient energy produces a particle and an anti particle. For this to happen with an electron-positron pair the minimum required energy of the photon has to ...
Exterminator2004's user avatar
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Pair production with two photons

I am studying the phenomenon of pair production and I learned that it cannot occur in a vacuum. Rather it occurs near a nucleus which absorbs momentum to keep the momentum conserved. Instead of a ...
Anindita Sarkar's user avatar
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On the (non)linearity of electromagnetism

As a student you are typically told that Maxwell's equations (ME) in vacuum are linear. However, it seems that for extremely high electromagnetic fields the equations for electromagnetism turn out to ...
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Electron-positron pair production cannot occur in empty space [closed]

I'm trying to prove that the electron-positron pair production cannot occur in empty space. From the conservation of energy we have that $$\hbar \omega = 2\gamma mc^2+E,$$ and from the conservation of ...
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Invariant nature of mass and particle annihilation [closed]

Since mass is a Lorentz invariant, it can never change to preserve the vectorial nature of the four-momentum and the other four vectors. Thus the only interpretation of the energy-mass equation that I ...
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Frequency dependence of Schwinger limit

Schwinger estimated a field of $10^{18}$ volts per meter as a point of "vacuum breakdown", over which spontaneous generation of positron-electron pairs becomes energetically favourable. But ...
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On the mechanism driving Hawking Radiation

I was reading up on Hawking Radiation and here's what I read in exact words: Physical vacuum constantly produces particle-antiparticle pairs and normally annihilate within a time given by Heisenberg'...
Ambica Govind's user avatar
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Pair-instability supernovae: how does it happen?

How does the formation of electron positron pairs increase the energy density and softens the EOS? I trrying to understand the pair instability supernova. In many texts and articles, it is written ...
Debasish Dutta's user avatar
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Is the vacuum spacetime around the Earth curved enough to make particles appear spontaneously?

I had a discussion with someone who said spontaneous particle creation had been seen in a lab-vacuum. I told him the spacetime around the Earth is not curved strong enough for that. But I have doubts ...
Deschele Schilder's user avatar
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Proof that infinite set of conservation laws imply no pair production

In QFT in 1+1 dimensions it is known that the presence of an infinite number of conservation laws, specifically in integrable systems like Sine-Gordon, implies that there is no pair production, and ...
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Is momentum of particles of pair annihilation same?

I am currently studying pair production and I realized a very weird trend (Acc. to me) that the momentum of both of the particles is taken the same? When I tried it's math it was very complicated(and ...
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According to the standard cosmological model, would an expanding gravitational field produce particles?

I found this article 1 about the production of particles in a time-dependent gravitational field. I have a few questions about it: According to the standard model of cosmology and our current ...
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Particle production in an expanding universe?

I was reading this interesting article which talks about particle production in an expanding universe. Usually this process is proposed to have occurred in the early universe, when the expansion was ...
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What frequency is needed for pair production?

I'd like to know exactly what frequency of a photon produces a pair e+/ e- , is it 2,4712x 10^20: must the photon have exactly that frequency or is there a range of tolerance? When the 2 particles ...
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In David Griffiths Elementary Particles Question 7.27, why do the spinors and Bjorken and Drell gamma tensor commute?

So, I have been trying to teach myself out of the David Griffiths Elementary Particles textbook, and I am trying my best to understand the conventions. I am looking at question 7.27 (found on page 270 ...
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Can Coulomb force of repulsion split two photons into positron and electron?

imagining a nano device which have ability to squeeze two repelling protons to a point that coulombic force of repulsion is near the maximum, then you direct two photons with energy of 1.0mev at the ...
Abel's user avatar
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Free energy from the vacuum?

An electric field with an intensity of the Schwinger limit $$E=\frac{m_e^2c^3}{e\hbar} \approx 10^{18} \hbox{ V/m}$$ is strong enough to create electron-positron pairs out of the vacuum by separating ...
John Eastmond's user avatar
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Why does production of electron come with either electron neutrino or positron?

I read that when an electron is produced, it always comes either with an electron neutrino or with a positron. Why is that so? Why doesn't an electron come instead with say a muon neutrino or antimuon?...
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Lowering the Schwinger limit with superconductors while considering the Unruh effect?

Unruh Effect is often left out in calculations regarding the Schwinger limit. I've been looking at different mechanisms for more easily attaining the Schwinger limit. So far, the only thing I have ...
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Hawking radiation: how can gravity rip a pair of virtual particles apart without creating another pair of virtual particles in the process?

To the best of my (limited) knowledge of theoretical physics you cannot rip a pair of virtual particles apart without investing enough energy to create another pair of virtual particles... If Hawking ...
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In Hawking's original Hawking radiation paper, how can we understand where the radiation comes from in the collapsing star spacetime?

In the original Hawking's paper "Particle creation by black holes" he first studies the collapsing star spacetime, and then the quasi-stationary phase of the black hole. In the collapsing ...
Display name's user avatar
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Chemical Potential of an electron or positron in a pair production reaction

In the Thorne and Blandford Modern Classical Physics text there is an exercise that walks you through deriving the density-temperature limit for pair production in plasmas. To do this they consider a ...
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Pair production and recombination with a more energetic beta particle

Can gamma particles with sufficient energy for pair production gain energy by recombining their positron with a more energetic beta particle than the one they produced? If yes, is this something that ...
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Can a particle anti-particle pair be created with initial particles conserved?

Is it possible to have a particle collision between 2 particles, have those 2 particles structures conserved, but also create a particle-antiparticle pair in the process? For example, you have a Pion ...
TurboChad's user avatar
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Can real particles be annihilated with virtual antiparticles and the other virtual particle pair replaces the real? Can this explain uncertainty?

Time goes from left to right. An electron is staying still, so from left to right, it's a straight line. A virtual photon got emitted from it, becomes a virtual pair of positron, electron, the virtual ...
Ng Xin Zhao's user avatar
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Is pair production possible in Classical Field Theory?

It is often said that quantum effects only become manifest in loops, and all tree-level calculations are classical. I am trying to figure out to what extent this claim is true. I know the claim arises ...
LordDirac's user avatar
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4 answers
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Does the Schwinger effect prove matter and antimatter can be created from a vacuum?

Virtual particles or vacuum fluctuations are the pair annihilation/creation of matter and antimatter particles in and out of the vacuum. Theses particles are virtual, but we know they exist because of ...
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How to calculate pair production cross section?

I've adapted the following equation from Wikipedia to calculate the pair production cross section $\sigma_x$ for a photon decaying into a pair of particles $x^+ x^-$ : $\sigma_x = \alpha \times(r_x)^2\...
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What is the minimum speed at which the proton has to move for antiproton production? [duplicate]

In a collision between 2 protons. Do each of them have to move at 1c, 0.5c.. ? The lower the speed, the less likely the production of the antiproton?
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At what speed do newly created protons move after a proton-proton collision?

I read that when 2 protons travelling at near the speed of light collide with each other, they create 3 protons and 1 antiproton. At what approx. speed those 3 new protons usually move once they are ...
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Can radio waves be converted to positron and electron when placed in weak electric field?

In particle physics, gamma rays can be converted to positron and electron when placed in strong electric field. My question is: What will happen if radio waves are placed in weak electric field? Will ...
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