Questions tagged [antimatter]

Analogous to matter, but with charge of the particles opposite to their ordinary matter counterparts.

66 questions with no upvoted or accepted answers
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703 views

Does positronium have a stable crystalline phase?

This is a long shot, but while the 100YSS conference is going on at Houston, i haven't been able to get a grip on myself and think in other, more mundane and short-term rewards as normal people do. ...
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148 views

Can antimatter form when a neutron absorbs a very high energy neutrino of the right flavor?

Art McDonald and Takaaki Kajita won the 2015 Nobel Prize in physics for discovering the oscillations between the 3 flavors of neutrinos; Electron, Muon, and Tau. This discovery showed that neutrinos ...
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If hawking radiation is true why isn't the entire universe glowing?

It says hawking radiation appears due to a particle and anti-particle pair one of which gets sucked in and other one escapes , these particles are said to appear out of nowhere , appear everywhere in ...
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Would cooling matter and antimatter to as close to Absolute Zero as possible allow them to coexist?

I was reading about Bose-Einstein condensates and how they affect matter and energy, and I wondered if "draining" that amount of energy from an atom of hydrogen and positronium would potentially allow ...
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How similar are the spin states and the matter/antimatter states?

Within the Dirac formalism, we have bispinors that represent both if a particle is spin up or spin down, and if a particle is an electron or a positron. And these representations are very similar. (...
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74 views

Symmetry responsible for equality of masses of particles

During my studies of basic particle physics the following question came up. What symmetry is responsible for equality of masses of particles and their antiparticles? In particular, is this symmetry ...
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310 views

What effects would a finding of Gravitational Repulsion Between Matter and Anti-Matter in the ALPHA Experiment have on Mainstream Theory?

The actual nature of the gravitational force between matter and anti-matter (attractive or repulsive) remains unsettled: See Are there experiments taking place right now that might show evidence for ...
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1answer
50 views

contradiction between total photon energy in the universe and early matter antimatter ratio

When looking at the energy count in the Universe, on one hand we are told dark energy 68%, dark matter 27%, regular matter 5%, neutrinos and photons a very small fraction (trace like). https://en....
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129 views

What happens when a particle and anti-particle collides of different masses?

If Hydrogen and an 'anti-Helium' come together will we get a hydrogen and a photon? I was wondering if antiparticles can be used to fuel some nuclear reactions and used to develop particles which ...
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122 views

Why are antiparticles associated with spin-flipped spinors?

In section 2.2 of Elvang and Huang's Scattering Amplitudes in Gauge Theory and Gravity (http://arXiv.org/abs/1308.1697), beneath equation (2.9), it is mentioned that $u^{\pm}=v^{\mp}$, where $u^\pm$ ...
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Why is it reasonable to recognize solutions to Dirac Equation as electron and positron?

I'm reading Griffiths' book and when it claims the first two components of plane wave solution to massive Dirac equation as electron and the “holes” of other two components as positron, it does not ...
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Is space not truly an empty vacuum but instead made up of densely packed particles of matter and antimatter?

In the livescience.com article Superpowered Chinese Lasers Could Soon Rip Open Raw Vacuum I read that quantum electrodynamics states that the vacuum of space isn't empty, rather it's made of densely ...
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Sakurai"s Comment Anti-particle in Klein-Gordon equation: Reversing momentum and Moving backward in time

In JJ Sakurai, p.492-493, he made Comments on Anti-particle in Klein-Gordon equation. By analyzing the current EOM, he said that charge current density is the same for all particles, (regardless ...
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172 views

Charge conjugation operator in second quantization

How can we write charge conjugation operator's action in second quantization's formalism? I don't know if I am explaining it correctly or not but I am interested in finding how can we write fermionic ...
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86 views

Could an antimatter-dominated end of universe fix CPT?

My question is about the apparent CPT violation of the observed universe, due to the imbalance of matter and antimatter, but first I have a motivating observation: General relativity respects time ...
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1answer
89 views

Do antiparticles exhibit different chemical properties?

In my physics class today. My teacher mentioned anti-helium and since I had never heard of anti-atoms (if you get what I mean by that) just antiparticles, this made me think: If we could produce anti-...
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Are we able to store low energy positrons in a magnetic field for arbitrarily long time?

And if not, what prevents us? Is there a mathematical equation describing the loss rate?
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88 views

Do quasiparticles have antiparticles?

Bosons (except for W) are their own antiparticles, since they have no electric charge. Charged fermions have antiparticles differing from the particles. Now my question is: has a charged ...
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Antimatter universe and Noether's theorem

I am studying Feynman's "symmetry in physical laws", where he talks about conservation laws for corresponding symmetries. (I know this is Noether's theorem, I am studying this from David Tong's ...
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1answer
145 views

Antimatter/Matter energy release

I am not a physicist, nor do I have a university degree, but I have a question that has been on my mind for some time. If Antimatter and Matter were created equally during the 'Big Bang' would the ...
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1answer
151 views

Are antiparticles just particle-shaped holes?

If particles are simply regions of space where certain quantum fields have non-zero divergence, are anti-particles simply the corresponding regions of opposite divergence? This seems like the ...
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31 views

Quantization of the massless neutrino field

If a massless neutrino or anti-neutrino is considered (in the whole post I consider neutrinos res. anti-neutrinos as mass-less), it is described by the Weyl-equation: $$\overline{\sigma}^{\mu}\...
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122 views

Testing if antimatter is backwards-travelling matter?

I've read about how antimatter can be modeled as matter traveling backwards in time before but always viewed this as a sort of mathematical curiosity. With this question I'm not so much asking if ...
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1answer
72 views

About the (retro)causality of an anti-atom

It is commonly said that one can view anti-matter as 'matter going back in time'. I'm trying to figure out how far this analogy goes. For an atom, it is well-known how that atom excites absorbing a ...
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33 views

Can the existence of antimatter be inferred from Matrix Mechanics?

It is well known that Antimatter was first predicted by interpreting the matrices that show up in the Dirac Equation as indicating its existence. Dirac factorizes $E^2=p^2+m^2$ ($c=1,\hbar=1$) into $...
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Have experiments looked at extra-galactic neutrino sources that would distinguish them from anti-neutrinos?

I understand the certain phenomenon even in other galaxies, such as supernovas, produce neutrinos that we can detect back here on Earth. I have also heard that we have experimental methods that can ...
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253 views

Can matter/antimatter “annihilation” produce “dark matter”?

I was thinking about the following reasoning: If a matter and antimatter reaction produces energy, this energy would have particles itself. I found out (reading...) that one (the main?) product are ...
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227 views

Antiparticle solution of the Dirac Equation

I'm really confused by the antiparticle solution of the Dirac equation. I follow Chapter 11 of Schwartz's book "Quantum Field Theory and the Standard Model" and find a couple of problems. In ...
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1answer
250 views

Why electron and positron annihilate would produce hadron (jet of gluon)?

Electron (fermion) is an elementary particle just like positron and they interact via boson which is photon, electromagnetic force. I like to know why is gluon (hadron) being emitted when electron and ...
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91 views

Why CP violation explains matter-antimatter asimmetry?

I'm studying Kaon oscillations and the Cronin & Fitch experiment on CP violation. I think I understand why CP is violated in the process but I don't understand why it means that matter and ...
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60 views

Pair production from photons

Given the following events are simultaneous can multiple photons "add" together to give the energy required to produce a positron, electron pair? $$ h\nu = m_e c^2 \gamma(v_1) + m_e c^2 \gamma(v_2) $...
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1answer
73 views

Creating two universes at the event horizon of a black hole

Using the uncertainty principle involving time and energy, is it possible a universe and anti-matter universe be formed at the event horizon of a supermassive black-hole? If so, could one the anti-...
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Annihilation and chemical energy

We have two atoms of hydrogen, one atom of oxygen, and their antimatter counterparts. Now consider the following cases: We let the hydrogen and oxygen react to obtain a molecule of water and thermal ...
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What happens if a photon emitted from an electron hits a positron?

Assume electron and positron are free particles, I think the emitted photon will become left or right circularly polarized depending on the sources. Am I just being paranoid or does the photon care ...
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117 views

anti-matter activation energy

In chemical reactions, there are usually energy barriers that must be overcome before a reaction can take place. It seems that such a phenomena also exists at the atomic level as well. For instance, ...
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122 views

Dirac representation between matter and anti-matter

If $|\psi \rangle$ represents a wavefunction through a column matrix and $\langle \psi |$ represents the dual vector in a row matrix and $|\psi \rangle \langle \psi | = \rho $ is the probability ...
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114 views

scaling laws for density and temperature of high-energy explosions

I'm wondering if there are heuristic ways to derive how the peak density and temperature of nuclear explosions scale with the amount of fissile/fusible material. Does it matter what the explosion ...
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1answer
45 views

How does one categorize antiparticles in flavor, family and generation?

$$\newcommand{\A}{\text{A}}\newcommand{\B}{\text{B}}\newcommand{\C}{\text{C}}\newcommand{\D}{\text{D}} \begin{array}{|c|ccc|} \hline { } & \text{1st} & \text{2nd} & \text{3rd} \\ \hline \...
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Feynman diagram literature for antiproton production via proton-proton collisions

I'm looking for literature, or anywhere I can find a Feynman diagram, which describes the proton-proton collision where antiprotons are produced in the following reaction: $$\rm{p} + \rm{p} \...
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1answer
48 views

Complex conjugation between particle/ anti-particle?

I am just a first year undergrad so I don't really know much about particle physics or the underlying mathematics. So I'm very sorry if the following question may be just stupid :D So I noticed that ...
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Are the electron and positron doublets in any mathematical sense?

I know left handed electrons and electron neutrinos are isospin doublets. Is there any analogous way in which an electron and a positron are related? My first thought is some sort time-parity doublet.
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How lepton numbers and baryon numbers of a particle are decided?

Suppose a new particle is discovered how will it be assigned a lepton and baryon number? Moreover, what difference would it make if the electron had +1 lepton number and a positron -1? The same ...
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What happens if matter particle and antimatter particle both carry no charge were to collide elastically?

I read that particle carrying charge is able to interact with photon so that when electron and positron collides they may be converted into pure photons, then what about neutron-antineutron collision? ...
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Are neutrinos or antineutrinos more prevalent?

As I understand it, neutrinos were first proposed to explain energy and momentum conservation in beta decay, as a hypothetical particle emitted together with the electron and proton. Thus Pauli gave ...
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Would a penning trap be disrupted if passed through the Earth's magnetic field?

Working on my essay for school and currently talking about using antimatter as a propulsion technique for rockets. At the moment I am talking about potential hazards and was wondering if passing ...
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Why do we have constraints on the baryon asymmetry of the universe and not the lepton asymmetry?

What is it about baryons that means that CMB observations can determine their asymmetry without also including a charged leptonic component?
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1answer
123 views

How does the negative energy solution to the Dirac equation predict the antielectron?

Please, can someone explain how the negative energy solution can be used to predict the existence of the antielectron?
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Is anti-sterile neutrino possible?

Due to the surplus of electron neutrino led people to suggest the possibility of 4th neutrino flavour, and it is thought to only interact with gravity and nothing else not even weak interaction. So is ...
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Grand-canonical ensemble for antiparticles

For a system of interaction free identical fermions/bosons in thermodynamic equilibrium, the average number of particles in a single-particle state $i$ is given by, $$n_i=\frac{1}{e^{\beta (\epsilon_i-...
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Relationship b/w spin-0 and complex scalar field

Why do the complex scalar fields defined using two sets of creation and annihilation operators (one for particle and one for antiparticle) describe spin-0? Is it because that they originated from ...