Questions tagged [elementary-particles]

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52 views

Does it make any difference if we switch particles to their antiparticle?

The title itself clarifies the crazy question. Does it make any difference if we switch particles to their antiparticle? By difference, I mean, Would everything alright with the laws of physics?
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1answer
19 views

Difference between two branches of $D^0$ decay

I'm trying to understand the following decays: i) $D^0 \rightarrow K^- + \pi^+$ ii) $D^0 \rightarrow K^+ + \pi^-$ The question came from Griffiths' "Introduction to Elementary Particles", ...
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1answer
10 views

Particle Energy Correlation with Probability Cloud

Is there a relationship between a particle’s momentum/energy and it’s wavelength? I know the Planck Equation for photon energy, but does this also apply to Leptons, Quarks and other Bosons?
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30 views

Is muon a point particle? [duplicate]

Im just a beginner in particle physics. As I have understand, electrons are considered as a point particle whose spin has nothing to do with original rotation around own axis but an intrinsic quantum ...
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0answers
33 views

Standard boost for one-particle states in Weinberg's QFT chapter 2

Weinberg's approach to QFT starts with particles which are not necessarily more fundamental than fields but are known more for certain. A particle of a particular species can have different momenta $p$...
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1answer
66 views

Gravitational collapse of the CMS detector at LHC and the future of particle physics [closed]

I have been a bit surprised about today's news that the CMS detector at the LHC has been wiped out during its collapse to a microscopic black hole. Although such an event has been predicted by some ...
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1answer
39 views

Is this calculation assuming that the neutrino is massless?

This is a calculation that I don't understand in Griffiths Intro to Elementary Particles page 105 second edition. This the decay of a pion into a moun and a neutrino. From Conservation of energy and ...
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1answer
260 views

March 2021 CERN discovery? What would be the properties of the new particle/force from decaying bottom (beauty) quarks?

This question is directed mostly at people who are expert in (beyond) standard model(s) of elementary particles, but input by other physicists or students is very much appreciated. A friend asked me ...
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20 views

Can the charge of $d$, $s$ and $b$ quarks be thought of as unitary charge? [duplicate]

Can the charge of $d$, $s$ and $b$ quarks be thought of as unitary charge? The electron is considered as an elementary particle but nevertheless has three times more charge than any of these three ...
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1answer
33 views

Photon Spin Griffiths Elementary Particles Book

In the Book "Elementary Particles" by Griffiths, Chapter 7.8 describes pair annihilation amplitude for $e^+e^- \to \gamma \gamma$. To obtain the final amplitude for the singlet state, he ...
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0answers
44 views

Is there a good reason not to think of gravity as the signaling of particles inward motion?

This is not about inventing new theories, let alone rejecting canonical ones. I am just wondering if general relativity (GR) could be interpreted like the following, or if there is something in GR ...
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2answers
120 views

Why is there not an infinite number of different particles? [closed]

Standard model has a number of fundamental particles, that are defined by various numbers and species, like charge, mass, etc. While those parameters are whole numbers or fractions, which would limit ...
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1answer
47 views

Does a positron go into decay process like some other elementary particles ? Electron, it's counterpart is stable and has a long half life

Can a positron decay? Or is it a stable particle like its counterpart the electron? (Reference: https://physics.aps.org/articles/v8/s138)
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2answers
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Can we fully describe the physical world as a collection of fields?

I'm new to the Physics SE, coming from a pure math background. I think my question is full of incomprehension and lack of basic knowledge, but here goes. I'm trying to wrap my head around the modern ...
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0answers
21 views

Formalizing the Askar'yan Effect

Wikipedia defines the Askar'yan Effect as... [The] Askaryan effect is the phenomenon whereby a particle traveling faster than the phase velocity of light in a dense dielectric... produces a shower of ...
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0answers
34 views

What is actually spinning in quantum spin? [duplicate]

Some texts say quantum spin is analogous to the spin of a planet in that it gives a particle angular momentum and a magnetic moment. However, as subatomic particles are tiny, the surfaces of charged ...
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2answers
78 views

How to correctly imagine a quantum particle, what does it look like?

I am a student, besides, only in the first year, so I apologize if the question seems stupid. How can you imagine a quantum particle, like an electron? This is a microscopic "ball" with a ...
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41 views

Considering the negative energy density in the Casimir effect and general relativity worm holes, are these experiments feasible?

The question came after I answered the question here, and reading the link provided where negative mass is needed to create wormholes, Microlensing by natural wormholes: theory and simulations We ...
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2answers
83 views

How did physicists run tests to try to study the internal structure of an electrons?

How did physicists run tests to try to study the internal structure of an electrons? How specifically did they run tests to try and study it? I've looked around online and I can't seem to find any ...
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2answers
193 views

Who predicted the existence of the muon neutrino?

The Wikipedia article on the muon neutrino says: The muon neutrino is a lepton, an elementary subatomic particle which has the symbol $\nu_\mu$ and no net electric charge. Together with the muon it ...
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4answers
95 views

Stern-Gerlach apparatus measures the magnetic moment. How to measure spin?

Since the Stern-Gerlach apparatus employs a magnetic field, it actually measures the magnetic moment $\mu$. If you assume a certain proportionality constant between $\mu$ and spin, then you can also ...
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2answers
61 views

Probability of forming a proton or neutron with loose quarks?

If I had two unbound up quarks and a down quark or two unbound down quarks and an up quark, what is the probability, if I bring them close together, they stick and form a proton and a neutron, ...
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1answer
68 views

Is an electron an ideal magnetic dipole?

Spin (for example of an electron) is described as an intrinsic form of angular moment, and we often say the electron has therefore magnetic moment, due to this angular moment. Well, I suppose when we ...
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1answer
66 views

Do charges have spatial dimension?

I don't know much about anything in physics. I hope you can bear with that. Let me start with my question do charges have any dimension, by this I mean physical dimension like length, breadth, height ...
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1answer
35 views

Behavior (wave or particle) of the photon absorbed by an electron

After being absorbed by an electron, does a photon continue to behave like a particle, or like a wave, or both?
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1answer
43 views

How is the difference in ground and excited state of baryons masses explained within QCD and SM?

How is the difference in ground and excited state of baryons masses ($\Sigma$ and $\Sigma^*$, $\Xi$ and $\Xi^*$ for example) explained within QCD and SM? Is it possible to calculate (predict) this ...
2
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1answer
113 views

Is any particle allowed within the laws of physics?

In the same way wormholes are possible but not guaranteed to occur naturally, is a theoretical particle possible such as one with a mass of a tonne and a charge of -3, or are there upper and lower ...
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2answers
60 views

Origin of particles at the Big-Bang

When we read writings on the Big Bang, in Planck's time (and even for some who try to imagine what was before), one talk about particles and antiparticles, but where do these particles and their ...
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1answer
50 views

Is PMNS neutrino mixing allowed in the standard model?

Some people say that the standard model does not allow for non-zero neutrino masses: it prevents renormalization, they say. Other people say that massive neutrinos with PMNS mixing are allowed in the ...
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1answer
58 views

Mass of the fundamental particles

I have always wondered that how do scientists measure the mass of a fundamental particle. Obviously they can't weigh it in a conventional machine we use to weigh other things in our daily life. And do ...
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1answer
49 views

Traces at pion decay

A negative pion breaks down into a muon and a muon antineutrino. What do the traces of the pion decay look like in a bubble chamber with a vertical, static homogeneous magnetic field? My ideas: The B-...
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1answer
32 views

What is the relationship between the different aspects of mass?

There seem to be several different ways in which mass manifests itself, in particular with reference to fundamental particles: Gravitational mass. Inertial mass. The coupling to the Higgs field. The ...
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1answer
41 views

Derivation of interaction potentials of fundamental forces

In Gauge theory of weak interactions by Greiner and Müller, they show the following superb comparison of the interaction potentials between particles as a function of separation: I have never seen ...
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1answer
47 views

Conserving angular momentum in elementary decay/reaction

I am trying to understand how to conserve angular momentum in a elementary decay/reaction. Consider the elementary reaction: $$ K^{-}(J = 0) +p(J = 1/2) ~\to~ \Omega^{-}(J = 3/2) + K^{+}(J = 0) + K^{...
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1answer
94 views

Difference between strong interaction and weak interaction?

I was looking at a straight forward answer on internet which I am unable to find. Can there be a strong interaction in which transformation of one quark flavour into other takes place(Eg. up quark -&...
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2answers
128 views

What precisely and mathematically does it mean to say gauge bosons as elementary particles?

In standard particle physics textbook, we say that photons, gluons and $W$ and $Z$ bosons are gauge bosons as elementary particles. However the gauge bosons are vector bosons and they carry the form ...
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2answers
174 views

Can a massless particle have both spin and charge?

Can a hypothetical elementary particle, at least in theory (according to the current science), have 0 mass and yet also have both spin and electrical charge (at the same time)?
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39 views

QCD methods - Dirac trace, trace in color space, trace in flavor space

What is meant by the following terms in QCD - Dirac trace, trace in color space, trace in flavor space, etc. Could someone explain with an example (For eg. what's the diffrerence between something ...
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0answers
23 views

Calculating the quark propagator while dealing with the color, Dirac & flavor matrices all together

$S^+$ is a diagonal matrix in color space, and is given as : $S^+ = S_{rg} ^+ \hat{P_{rg}} + S_b ^+ \hat{P_b}, where, \hat{P_b} = 1_c - \hat{P_{rg}}$ is the projector on blue quarks, $\hat{P_{rg}}$ ...
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0answers
17 views

Frequency of photons and speed in media

I'd like to ask a few questions about photons, not as a professional of physics. Frequency: Since it's connected to the frequency of the wave composed by the stream of photons but can be defined for ...
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5answers
6k views

Are protons bigger than electrons?

In every text/ physics book that I've read, Protons are mentioned as particles that are bigger, way bigger 2000 times to be precise, than electrons...I believed that until a few minutes ago when I ...
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1answer
92 views

How to transform a given Lagrangian to a Nambu-Gorkov basis?

With reference to the Nambu (or famously, Nambu-Gorkov) transformation in this paper, could someone explain the reason behind using the 3rd Pauli matrix in the Lagrangian after equation (2.3) (would ...
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2answers
115 views

If virtual particles are considered to be just mathematical constructs, does this imply there are no corresponding physical processes?

Some people consider all elementary particles to be non-existent. They tell us that they are changes in the field configurations that last which are called "real particles", while those that ...
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1answer
54 views

How to prove the equivalence of two definitions of hypercharge?

Before introducing top bottom and charm quarks,Strong Hypercharge is defined in the following two ways--- $1.\,\,\,Y=B+S$ where $Y,B,S$ are the hypercharge, baryon number and strangeness respectively. ...
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1answer
57 views

Conservation of chirality in non-weak elementary particle interactions

Chirality is not conserved in propagation (e.g., electron oscillates between left and right chiral). But is chirality conserved in interactions? What is a good reference paper or book for this notion ...
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49 views

Parity of Particles

Like charge, spin,etc.. Parity is an intrinsic property of the particle. As I read in Grifith's introduction to elementary particles book , he states parity mathematically but I am not able to see it ...
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2answers
59 views

Entropy always increases. Then why did elementary particles come together to form an atom?

It is generally said that entropy always increases. But after the Big Bang elementary particles came together to form an atom. Isn't that paradoxical ?
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1answer
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Why the mesons $\pi^0$ and $\eta$ are “degenerate”

I don't know anything about elementary particles, but reading the book by Zeidler on p158, table 2.8 one can observe the quark content of baryons and mesons. It is strange that the $\pi^0$ meson has ...
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1answer
64 views

Question about a relativisticaly accelerated harmonic oscillator

How can the speed of oscillation of a harmonic oscillator be affected if somehow it got accelerated to a relativistic speed perpendicular to its oscillation? Can this be compared with the effect on ...
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1answer
41 views

Which is the meaning of these masses?

When reading about the masses of neutrinos in the HDM (Hot Dark Matter) model of the universe, I came across the following equation: $$\tag{1} \sum_i m_{\nu_i} = 92 \Omega_\nu h^2 \text{eV}$$ My ...

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