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Questions tagged [elementary-particles]

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1answer
218 views

Muon-electron mass ratio

I was watching this video about The Standard Model and at 24:56, Michael Peskin said that Feynman tried to explain the ratio of muon to electron mass by doing some QED calculations and within an hour ...
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1answer
36 views

Fused Electrons Spin [closed]

If it was possible to make two electrons fuse, would it also be possible to increase the magnitude of that object's spin since it is not an elementary particle?
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1answer
229 views

Physics of K meson

$K^{0}$ meson consists of a $d$ quark and an $\bar{s}$ antiquark. Its antiparticle $\bar{K^{0}}$ consists of an $s$ quark and a $d$ antidown quark. $$|K^{0}\rangle=|d\bar{s}\rangle$$ $$|\bar{K}^{0}\...
2
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1answer
556 views

Decay of Z boson

I have following queries regarding the decay width of Z boson. In thisThomson's lectures, page 479, it says that decay of Z to hadrons have a large cross section because of factor 3 from colors. But, ...
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2answers
617 views

Are quarks/electrons different sizes (physically/in terms of mass)? [duplicate]

i.e. is an electron bigger/smaller than a strange quark? Is a strange quark bigger/smaller than an up quark? Or are they all the same size? Leading on, are electrons the same size (as in physical ...
2
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1answer
146 views

Atmospheric neutrino oscillations

Cosmic rays primarily consist of protons, which primarily decay into pions upon impact with the atmosphere of the Earth. The pions decay according to $$\pi^+ \to \mu^++\nu_\mu $$ and $$\pi^- \to \mu^- ...
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2answers
127 views

What does Quantum Spin Cause? [duplicate]

How do particles with different Quantum Spin Numbers interact differently with other matter? What does spin cause? I understand that electrons etc act as if they are spinning my emitting a magnetic ...
9
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4answers
3k views

Elementary Particle of Magnetic Field

If gravity - a field force - has an elementary particle, the graviton, why don't other field forces like magnetic fields have their elementary particles? I mean, why isn't there a magneton? Or, what ...
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0answers
27 views

Self-contained primer on species of elementary particles

I'm studying for the GRE and noticed that all my knowledge of elementary particles is purely hypothetical: i.e., I can calculate counterterms for a pseudoscalar Yukawa theory, but I don't actually ...
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3answers
109 views

For a centre-of-mass energy of $3\,\mathrm{GeV}$ is it possible to make a charm quark?

This is not strictly a homework question (but I have added the tag anyway). I am using an answer from a given question which states you cannot make a charm quark if given a centre-of-mass energy $3\,\...
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1answer
1k views

Are gravitons real? [duplicate]

Is graviton a particle? What's your view on this? Sence physics is the study of matter, it seems to me forced to believe that the gravitational force are particles. There are no particle called ...
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1answer
80 views

Which are the obstructions for $E_8^L\times E_8^R$ unification?

After left-right symmetry extension of the standard model, $$G' \times SU(2)^L \times SU(2)^R$$ it would seem that a logical pathway to grand unification is to try to obtain it by breaking down from ...
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1answer
195 views

What is the smallest particle? What is the building block of an electron? [duplicate]

I'm curious. Why when I was 5 years old did I rip things apart in half... Always trying to get another half... is it endless? I took a leaf and ripped it in half, and kept on going... God?
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1answer
106 views

Polarization of elementary particles

I hope it's all right to ask a question about some very basic intuition in particle physics. I was looking into these (very nice) notes of Matthew Schwartz, I guess from his course on QFT: http://...
2
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1answer
69 views

How to describe Partial Wave Analysis in easy words?

Like the question title says, can anyone describe the fundamental principle of partial wave analysis in easy words? Without equation, just by saying maybe why it is so useful in particle physics and ...
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2answers
397 views

How to visualize the propagation of a wave?

Waves can be visualized as a waveform, with crests, troughs, wavelength and amplitude. Water waves (wind waves) fits excellent in this model. However, there is many kind of waves in nature. Is it ...
1
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1answer
367 views

Upness and downness

There is a flavour for almost any type of quark [from here]: isospin: $I_3=\frac{1}{2}((n_u-n_{\bar{u}})-(n_d-n_{\bar{d}}))$ strangeness: $S = −(n_s − n_{\bar s})$ charmness: $C = (n_c − n_{\bar c})$...
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1answer
336 views

What is the mathematical definition of a classical elementary particle?

In the (non-statistical) setting of quantum mechanics, the rôle of the state space is played by a projective Hilbert space $\mathbf{P}(\mathscr{H})$. Elementary particles are then more or less defined ...
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1answer
73 views

If a black hole is made by a hypothetical particle above Planck mass and it has angular momentum will it be a ring Kerr black hole? [duplicate]

If a single subatomic hypothetical fundamental particle incapable of decay (such as an electron) with a mass exceeding Planck mass possessed angular momentum and it collapsed into a black hole, would ...
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3answers
3k views

If electrons have a negative spin of 1/2 do all particles also have the ability to have a negative spin?

I've been told that electrons can have $+{1\over 2}$ or $-{1\over 2}$ spin. And that because of the Pauli exclusion principle this is how they can occupy the same shell. But when I look online I only ...
11
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2answers
7k views

What is the difference between a neutrino and an antineutrino? [duplicate]

Since an antiparticle by definition is a particle with the same mass but opposite charge, how is there such a thing as an antineutrino? A neutrino has 0 charge so could not have an opposite. So why ...
3
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2answers
929 views

How does the Higgs boson give mass to other elementary particles like electrons? [duplicate]

So, the nucleus of an atom can be broken to protons and neutrons, and those can be broken down to quarks. Electrons however are a different story, they can't be broken down since they are elementary ...
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1answer
155 views

Can elementary particles be abstractly represented as polytopes or geometric functions?

In Quantum Field Theory, elementary particles are represented like localized oscillations (localized transverse spherical standing waves) of their underlying fields, or superpositions of their normal ...
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1answer
61 views

Is chirality an intrinsic property of elementary fermions?

Is it the case that chirality is an intrinsic property of elementary fermions? I mean, is it the case that all electrons have left handed chirality while all positrons have right handed chirality? And ...
1
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1answer
366 views

With point particles being smaller than their Schwarzschild radius are they forever cloaked in a black hole?

My understanding of point particles is that they have mass and are dimensionless. If this is so then wouldn't the mass cause the particle to have a Schwarzschild radius which would then make the ...
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4answers
315 views

When did the Universe turn from a quantum system to a multi-particle system?

Background: The properties of quantum particles and fundamental fields are the same all across the Universe. Each particle of a certain kind is identical to all other particles of that kind ("a ...
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3answers
1k views

About the reason why the change of a muon into an electron plus a photon is not seen

Let me state first that I don't think this is a duplicate of the mentioned question, though the basic thought is the same. Nevertheless, I come up with the prequark rishon theory of Harari, which ...
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2answers
895 views

How can a truly elementary particle change into other particles? [duplicate]

Consider for example the next changess: The change of a Higgs and the change of a muon [in the diagram of which we also see the decay of (virtual) $W^-$ into an electron and its associated neutrino)]....
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0answers
269 views

Best book on the theory of Standard Model of particle physics? [duplicate]

I am interested to learn a concise and complete theoretical overview of the currently accepted Standard Model of particle physics. Standard Model books that I have encountered so far (like Bjorken and ...
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1answer
162 views

What does it mean for a particle to have volume? [duplicate]

As far as I understand, we do not know whether an electron is a point particle or not, but we have a very low upper bound for its potential volume. If it turns out that electrons do have volume, what ...
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1answer
432 views

Have quarks been observed in free states?

I had been reading a book in particle physics very recently. The book has probably been written in the late 90's, (and obviously before 2000), and states that quarks, the underlying particles in all ...
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2answers
65 views

Does wave-like functions of electron suggest that it is a composite?

Even though this is currently described with a probabilistic approach, can't it be that we are yet to discover smaller particles in an electron?
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0answers
37 views

Confusion regarding fundamental particles [duplicate]

As per standard model, particles like electron and quarks are considered as the elementary particles (no further division into simpler particles possible). Are those particles really elementary or ...
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1answer
90 views

What is/might be the basic component that makes up elementary particles? [duplicate]

What is/might be the basic component that makes up elementary particles (like electrons and quarks)? Is this the stuff concerned with “strings” (string theory)? Can anyone explain it in layman's terms?...
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2answers
551 views

Are all 'substances' made of atoms?

Is there any other large collection of particles other than atoms that would fit our traditional intuitive definition of a substance? Something that would appear similar to a solid liquid or gas. ...
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1answer
238 views

Does the existence of particles with an electric charge that varies from 0 to 4/3 proof that more elementary particles with charge 1/3 or 0 exist?

Elementary spin 1/2 particles vary in electric charge from o(neutrinos), 1/3(anti-down-, anti-strange-, and anti-bottom-quark), 2/3(up-, charm-, and top-quark), to 1 (electrons, muons and taus). ...
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1answer
219 views

Reverisbility of pysical laws (perpetual motion of atoms) proves the atomic/quantum hypothesis [closed]

As I understand, the atomic hypothesis and quantum theory says that we cannot divide the matter infinitely. Atoms were discovered 100 years ago but why are they indivisible apart? It is said that they ...
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2answers
103 views

The Big Bang and universal elemental abundance. Predictions seems bad and unconvincing?

Allow me to preface this question by stating that I am not a Big Bang denier. I am reading the book A Universe from Nothing by Lawrence M. Krauss. In his book, he presents the following card as one ...
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5answers
8k views

Do photons truly exist in a physical sense or are they just a useful concept like $i = \sqrt{-1}$? [closed]

Reading about photons I hear different explanations like "elementary particle", "probability cloud", "energy quanta" and so forth. Since probably no one has ever seen a photon (if "seen" it supposedly ...
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0answers
38 views

Quantum transitions

In an atom, an electron absorbs a photon and jumps to a higher energy state. Thus the wavefunction for electron changes. 1.How does the photon interact with the initial wavefunction? How does this ...
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1answer
92 views

Is all matter formed from Elementary Particles?

If we could break down all matter, would everything break down to Elementary Particles? Or if nothing existed in the world except Elementary Particles, would they interact with the Higgs Field until ...
3
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2answers
1k views

Volume of a Photon?

I understand that photons, like the other elementary particles, is a point particle and doesn't technically have definite boundaries. However, protons and other baryonic matter have a mean atomic ...
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0answers
57 views

The structure of the electron as a particle

has anyone found the minimum radius of the electron including the magnetic field ( dipole moment) ? The 'classsical' radius only uses the electric field, and so is a minimum radius for a purely ...
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1answer
66 views

Verifying the consistency of a quantum field theoretic cross-section formula

Consider the scattering $$e^-e^-\rightarrow e^-e^-$$ in QED. The cross-section is a Lorentz invariant quantity and therefore, given by $$\sigma=\sigma(m_e,e,s,\theta)$$ where electron mass $m_e$, ...
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3answers
235 views

How can we experimentally tell the difference between particles with and without rest mass?

We only observe their decay products and that is what the rest-mass is reconstructed from. Also, there is a whole issue of running coupling which means that rest mass per se actually doesn't make ...
6
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2answers
287 views

Can two nuclei with the same number of protons and neutrons be different?

In school, the nucleus is often portrayed with this caricature $\\$ $$$$ My question is: can two nuclei with the same number of protons and neutrons be different? In other words, can the protons and ...
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1answer
811 views

Particle Detector: dE/dX and momentum resolution

I'm reading an article describing a particle detector. I did not understand the following things in it. "The drift chamber (of this detector) was described as having a dE/dX resolution that is better ...
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1answer
513 views

Mass Resolution- Particle's width in Particle physics?

I'm not 100% sure. but I think that the width of a particle could change depending on the decay channel. for example: The J/psi's mass resolution could be 40 MeV or in other cases 8 MeV. So I would ...
5
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3answers
220 views

Any proof that inflatons exist?

According to the theory of cosmic inflation, the particles that cause inflation are called inflatons. My question is how strongly a cosmologist working on inflation proves in the existence of such ...
2
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1answer
302 views

Decay, scattering and forces in quantum field theory

In quantum field theory, the concept of a force is not explicitly present, and we speak of interactions. I guess we could say that a force is an emergent phenomenon. Interactions manifest themselves ...