Questions tagged [antimatter]

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

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Big bang should have made up an equal amounts of both matter and anti matter, then why don't we see such?

So, my question arises that how do we know that normal matter is more in quantity or number than anti-matter? Research at ALPHA said that anti-matter that the spectrum of hydrogen and anti-hydrogen ...
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Can we add matter and antimatter to the universe?

Sorry if this is a basic question, or there is a glaringly large hole in my reasoning, I am not smart, and saw a documentary and did some googling, after which I decided to ask people with actual ...
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Derivation of operator version of the classical wave equation

I have the following summarised derivation for the operator version of the classical wave equation for massless and material particle. My question is about the statement: However, a problem is that ...
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Why have Majorana fermions not been detected?

There are two types of fermions - Dirac's and Majorana's. Majorana's fermions are their own antiparticles and they have not been detected yet. Sometimes, it is conjectured that e.g. neutrinos could be ...
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Anti-commutator relations between fermions and anti-fermions [duplicate]

Some lecture notes on quantizing the Dirac field claim that all anti-commutators between creation and annihilation operators should vanish, except for the one between the creation and annihilation ...
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Pauli Exclusion Princple for a fermion and antifermion

I understand that the Pauli Exclusion Principle applies only for identical particles, so that a fermion and an anti-fermion should be allowed to be in the same state. However, when I look at the ...
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Antiproton interaction with hydrogen

What would happen if an incoming low energy antiproton collided with a hydrogen atom? Would it bounce off because of the orbiting electron or would it annihilate with the proton?
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Positron mass in Dirac sea

I know that the modern correct interpretation of positrons is based on Fock's idea of regarding electrons and positrons on the same footing. But my question is: How did Dirac justify the mass of ...
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Do $C$-parity eigenstates have to have well defined exchange symmetry?

Obviously for C-parity eigenstates of a particle and itself (which is its own antiparticle) this is a wavefunction of identical particles and will thus have well defined exchange symmetry. I also ...
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May $e^+$ and $e^-$ annihilate with two spins so oriented that they add up instead cancel out?

May $e^+$ and $e^-$ annihilate with two spins so oriented that they add up instead of cancel out? If this is not possible what science says about the mechanism that stops this from happening? Does ...
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Are Dark Matter and Antimatter “states” of matter? What broad category do these fall into?

This question is more to do with what matter is and what matter is not. We know that there is something called matter, which is basically everything we see around us. 17 fundamental particles make up ...
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Electrons and Positrons: What happens when a positron beam in-phase with diffracted electrons is used to make a hologram with the anti-electrons?

Suppose two independent beams of positrons and electrons are filtered such that each is in phase with the other (correction: this probably isn't possible, although terminology to this effect is out ...
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Is the process $\pi^{-}+p^+\to\bar{n}+n+n $ allowed?

Is the process $\pi^{-}+p^+\to\bar{n}+n+n $ allowed? Is there any collision involving only the mesons and baryons that would produce antibaryons (along with other particles)?
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Dirac fields: Do particle and antiparticle creation operators act differently on the vacuum?

Given a Dirac field $$\Psi(x):=\int\frac{d^4k}{(2\pi)^4}\delta\left(p_0-\omega(\mathbf{k})\right)\sum_s\left(a_s(k)u_s(k)e^{-ikx}+b^\dagger_s(k)v_s(k)e^{ikx}\right)$$ with the creation operators $a^\...
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Positrons in space, are they remnants of baryon asymmetry?

This recent paper By observing 1.9 million positrons (out of 107 billion cosmic rays), the AMS Collaboration finds that the energy dependence of the positron flux is very complex. ... Overall, the ...
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How come positrons don't destroy all the electrons in the universe?

What it says on the title. How come all the positrons don't destroy all the electrons in the universe and vice versa? They are attracted to each other due to opposing charges.
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Could it be that at the big bang equal amounts of matter and antimatter were created, but the antimatter got stuck in black holes? [duplicate]

I recently watched PBS spacetime's video series on the black hole information paradox. Where they first discussed the no hair conjecture and then later also the true destruction of information by ...
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Could there be a region of the universe that is dominated by antimatter?

I was reading some texts explaining that since our region of the world is overwhelmingly dominated by matter, and not by anti-particles, this suggests that in some region of the universe, there will ...
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Discovery of the Anti-Electron - Question

I have a general question concerning the description of a Figure, taken from Griffiths' Introduction to Elementary Particles, page 20: I'm afraid I do not really understand the last part: How is it ...
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How can we detect antihydrogen?

From a mathematical standpoint (CPT symmetry) it is most probable that antihydrogen has the same spectra (absorption and emission) as hydrogen. The CERN confirmed this hypothesis to a high accuracy ...
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Is it possible that antimatter has positive inertial mass but negative gravitational mass? [duplicate]

Newtonian mechanics seems to allow for both positive and negative gravitational mass as long as the inertial mass is always positive. The situation is analogous to electrostatics but with the ...
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Negative Energy in the 4-momentum of an Antiparticle?

By the very definition of an antiparticle, we know that it has a negative energy $E$; which, in natural units, is: $$E = -\sqrt{m^2 + p^2}$$ where the symbols have their usual meanings. Thus, If we ...
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Do two specks of antimatter experience antigravity between each other? [duplicate]

Do two specks of antimatter experience antigravity between them? If no is the answer then what 2 specks may ever be the cause of that?
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Some questions about Feynman Diagrams

I have a few simple questions about Feynman Diagrams: Why, when $W^+$ or $W^-$ bosons are involved, sometimes the sign + or - is shown and sometimes not (example1, example2)? Why the arrow is usually ...
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Why would having more matter than anti-matter neutrinos help make the rest of the universe be tipped towards matter?

My middle school daughter became fascinated after reading the article below about how the matter/anti-matter balance of neutrinos helped create the big bang, so decided to make it her term research ...
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Have there been any experiments that examine the collision between an anti-down quark and an electron?

Like many people, I've been chasing down idle curiosity, trying to get a better understanding of how certain particles interact with each other. I have been particularly unsuccessful in trying to pin ...
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Universe and Anti-Universe pair [closed]

Two years ago Latham Boyle, Kieran Finn and Neil Turok, in their work CPT-Symmetric Universe, proposed that the pre and post bang eras constitute a universe/anti-universe pair. For Anti-universe in ...
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Do extremely high-voltage power lines emit positrons?

Stretching across China, from the Xinjiang region in the west to the province of Anhui in the east, there's a ±1,100 kV high-voltage direct-current transmission system. I'm not 100% sure what "±1,...
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Could antimatter have disapeared from the universe simmilarly as observed matter from collisions of black holes?

As matter inside a neutron star or black hole can vanish through collisions could be possible that antimatter did so more than matter in the very beginning of the universe through a high energetic ...
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Is it possible to make hibrid atoms? [closed]

Is it possible to make an atom which is half matter and half antimatter (mostly meaning that it's particles are equaled) ? And if it would be possible, how this atom would behave comparably with its ...
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Majorana neutrinos

I don't know much about this topic so I am sorry if my question is silly. As far as I understand if neutrinos are Majorana particles, one consequence is that neutrinos are their own antiparticles. ...
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How much anti-matter (combining with matter) is needed to give a rocket a velocity that approaches the speed of light (say 95 % of c)? [closed]

A question (very hot presently) about the propulsion of a rocket with compressed air prompted me to ask a somewhat related question. Maybe one sunny day it will be possible to construct an anti-matter ...
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Is there any reaction where electrons or protons get directly converted to energy, and are destroyed as a consequence?

This question is not about fission or fusion reactions, or changes in mass/energy as the speed of a particle changes. The number of protons (including protons within neutrons) and electrons pre- and ...
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Why is there matter when all of it should have annihilated with antimatter?

The theory is that after the Big Bang, photons turned into matter and antimatter particle pairs, but they should have all annihilated with each other. Since there would be an equal amount of matter ...
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Does a non-relativistic proof of spin-statistics theorem exist?

There are lots of questions here related to the spin-statistics theorem, though none of them answer this question directly. I had the notion that one can only prove the theorem on relativistic grounds ...
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Can I write a complex field, in some cases, as a real field?

I am learning quantum field theory. Now I am considering this case: Suppose a spin-0 particle which obeys the Klein-Gordon field equation and its anti-particle obeying the same equation do not have ...
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In matter-antimatter interactions, what's the meaning of “touch”?

In this question, the top answer gave a seemingly good description of the particle interaction, but what exactly the interaction is seemed to be left unstated. I've only the most rudimentary ...
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A theoretical question about matter/antimatter and capacitors

Let's assume that the experiment is done in a vacuum and there's a circuit as in the attachment. The values of voltage/resistance/capacitance are insignificant. Assume that the right terminals of ...
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How is the neutral kaon stable?

A neutral kaon is a mix of a particle and antiparticle, in layman's terms. In layman's terms, how is this possible without there being annihilation?
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Fermion LSZ reduction / Greens function

In Matthew D.Schwartz book, 'Quantum Field Theory and the Standard Model' page 227/8 he talks about Feynman diagrams in QED, specifically $e^{-}e^{-} \rightarrow e^{-}e^{-}$ u and t channel tree level ...
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In the QFT Lagrangian, what does the adjoint of $\psi$ represent, physically?

In the EM Lagrangian, the QCD Lagrangian, and the charged and neutral weak current Lagrangian, there is always a $\psi$ term and its adjoint $\bar{\psi}$. The $\psi$ term can represent a Dirac spinor ...
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Antimatter Generation With The Help Of A Plasma Globe

I know this sounds absurd, but after doing a little research I found that it may be possible (not entirely, but that is why I am asking about this here). I have been reading up on antimatter and ...
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Do the right-chiral electron and left-chiral positron interact with the anti-$W$ boson?

I've been reading Flip Taneda's 'quantum diaries' articles, and he references the famous fact that the W boson (weak force) only interacts with left-handed electrons and right-handed positron. BUT... ...
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Can a right-chiral electron annihilate on contact with a right-chiral positron?

Or, do two particles have to be 'anti' in every sense of the word? (Opposite charge, opposite chirality, etc.) Edit: Just to clarify... Antiparticles can have multiple properties that are 'anti' of ...
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Meson could include both matter and antimatter?

I wonder eta and pion could exist containing up quark (anti up quark)? Isn't there pair annihilation in this meson?
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Meson conservation [closed]

Why meson conservation doesn't exist?
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When matter and antimatter meet and annihilate, is that considered 'decay'? By the EM, weak and strong forces simultaneously?

Matter-antimatter destruction is 'decay', correct? And since antimatter particles are considered the opposite of matter ones in every way, not just in terms of EM charge, does that mean they are ...
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Why is it assumed that the Big Bang produced equal parts matter and antimatter?

It is well-known that a major open question in physics is why the Universe appears to be made almost entirely out of matter, with next to no antimatter, despite the two being strictly symmetrical ...
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Can Chirped Pulse Amplification (CPA) be used for creating antimatter?

In this excellent answer by Emilio Pisanty, he states that: Of course, all the cool laser-driven QED stuff at the top of that second diagram: if your laser is strong enough that, if you release an ...
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Annihilation in free vacuum?

I remember expositions on Feynman diagrams (like Flip Tanedo's https://www.quantumdiaries.org/2010/02/14/lets-draw-feynman-diagams/) and others representing electron-positron anihilation with emission ...

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