Questions tagged [elementary-particles]

The fundamental subatomic particles that have no (currently known) substructure. These include fermions (quarks, leptons, antiquarks, and antileptons) and bosons (gauge bosons and the Higgs boson). A particle containing two or more elementary particles is a composite particle.

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Classification of elementary particles that have been proposed to explain dark matter

I'd like to write a paragraph about elementary particles that have been proposed to explain dark matter, but I don't know exactly how to classify these particles or arrange them: Scaler field -- ...
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Can the number of each particle in the universe have changed after a black hole evaporation?

Imagine a black hole that has formed from a neutron star, so from neutrons only. The neutrons appeared from a proton and an electron while an electron neutrino was sent into the surrounding universe. ...
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Can singularities' spin be related to the quantum spin of elementary particles?

We do know that black holes can and sometimes do have angular momentum, as described by the Kerr metric. Though I have not found anything about the description of the angular momentum of the contained ...
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Standard Model searching for new physics in the wrong direction? [closed]

What makes the SM so confident that any possible new discrete elementary particles must exist outside and separated from the known elementary particles? What is the definitive theoretical proof we ...
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Are all elementary massive particles distortions in the Higgs field? [closed]

I am confused, as I understand it, all elementary massive particles are sourcing from the Higgs scalar field thus are all distortions in the Higgs field. How this differs elementary from the old ...
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Is spin of elementary particles same as the rotation of a planet? [duplicate]

By the word spin of elementary particle, one would imagine the particle to be rotating around its own axis, just like a planet rotates, but is it actually true? While spinning does an elementary ...
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About QFT and wave packets as particles

I read Ryder's book on QFT but I couldn't understand what in facts are localized particles which are really observed and do they have any place at all in QFT. So I watched a Zee lecture in YT https://...
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Neutron star near black hole mass in a moving frame [duplicate]

Consider a neutron star with a mass close to that necessary to form a black hole. In a moving frame, it has additional kinetic energy, and its energy density should increase. Why is it not possible ...
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Mesons sea and valence contribution

I want some clarity regarding sea and valence quarks. Is sea quarks and gluons contribute in the properties of mesons like masses, spin distribution etc. and how they will contribute?
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Can an elementary particle truly be destroyed?

Much like the title above, can they be created (from absolute nothing) or destroyed (into absolute nothing), with nothing in this case being nonexistence. Taking into account the idea of quantum ...
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Transform helicity amplitudes to spin amplitudes using a transition matrix

So I would like to transform the helicity amplitudes (F0, F'0, ... F2') in proton-antiproton scattering to spin amplitudes (a,b,...g). The helicity amplitudes are given in the notation: Now, I denote ...
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Is it possible that there is a third class of fermions?

There exist six types of quarks, and six types of leptons, both divided in three generations. Could there be some other new class of exactly six particles, similar to these, but with properties such ...
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(Solved) Why does this Kaon interaction need the intermediate up quarks?

In the answers to a set of practice questions my lecturer shows that we need these up and antiup quarks in the middle, but I don't quite understand why we can't go straight from the down to strange ...
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How can beta decay change elementary particles?

From what I read on beta minus decay, when it happens a neutron gets "converted" into a proton, an electron and an electron-antineutrino. I also read that both the neutron and the proton are ...
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Extending Wigner's Classification with Gauge Symmetry

In Wigner's Classification, as far as I understand, one uses unitary irreps. of the Poincare group for treating an elementary particle, since then mass $m$ and helicity $h$ emerge naturally as ...
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Could a non-pointlike structure of elementary particles explain their spin?

Elementary particles are considered point-like. Which makes the concept of spin rather problematic. It can neatly be described by group theoretical considerations, but that offers no explanation what ...
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Neutrino Oscillation and Probability

I am a fresher in a university pursuing physics major. I have been very passionate about neutrinos. So, I started studying them. But I have realised that, it requires a lot of mathematical physics ...
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Can fundamental particles have magnetic/electric quadrupoles, octopoles, and higher-order moments?

Fundamental particles come with magnetic and electric charge, which makes the particles into a monopole source for the magnetic and electric fields. Of course, the magnetic charge is zero for all ...
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Is inertia present at the level of elementary particles?

Is a more massive elementary particle will experience more inertia in a one-on-one particle interaction?
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Are there really random fluctuations of particles?

From classical physics, we know that particles are affected by thermal fluctuations. In turn, I wonder if there are any fluctuations of the particles that follow from QM and that are truly random. I ...
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Cryogenic Particle Detectors

Recently, I started reading about Neutrinos, their types, oscillations and their detection. Today many experiments are being conducted to detect and measure oscillations of sterile neutrinos and anti-...
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Could the equal amounts of positive and electric charge point to equal amounts of matter and anti-matter?

The universe is electrically neutral because the electric charges of all quarks and leptons cancel. If particles are electrically charged, then there are equal amounts of positive and negative ...
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Is leptons annihilation one process of 4 particles simultaneously or two independent processes of 3 particles? [duplicate]

Why leptons annihilation is not 4-particles, and it is represented in the form of two 3-particles? If the pair of an electron and a positron has formed a positronium particle, then what is virtual ...
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What is a particle in QFT framework? [duplicate]

I've heard that in QFT a particle is a local excitation of a quantized field, but I can't understand how can I imagine this. For example in the second quantization of the Klein-Gordon field we get an ...
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Why do $Z$ or $H$ bosons can decay to a pair of quarks $t^+t^−$ with mass larger than boson in the inertial reference frame of boson?

The masses of $Z$ or $H$ bosons is less than the sum of the mass of two $t$ quarks. Why do $Z$ or $H$ bosons decay to a pair of quarks $t^+t^−$ with mass larger than boson in the inertial reference ...
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How long can an unstable particle live? Is there a theoretical upper limit?

Somehow, in all my years of studying and reading, I have never come across an answer to this question.... Is there a fundamental limit to the lifetime of even the shortest-lived subatomic particles, ...
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Is there data for natural background radiation measurement?

I am looking for raw data of alpha/beta/gamma particles natural background long-term measurement (preferably day by day or second by second for at least a few weeks), but cannot find any. I would be ...
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Physical picture of electron spin?

Can the spin of an electron be understood as originating from an open string rotating around a perpendicular axis through its midpoint?
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Size of electron? [duplicate]

It is claimed that the electron has a size less than $10^{-19}$m. I presume this is based on high-energy scattering experiments. But isn’t this apparent size simply a function of the high energy of ...
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Do the mean lifetimes of short-lived particles follow a Gaussian (or 'normal', or 'standard') distribution? When plotted?

For instance, the average 'mean' lifetime of a muon is just over 2 microseconds.... If I plotted many, many muon lifetimes after careful experimentation, would the chart show a Gaussian distribution? ...
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Why massive elementary particles come in different flavors?

Neutrinos come in 3 flavors: electron neutrino, muon neutrino, and tau neutrino. Quarks come in 6 flavors: up, down, top, bottom, strange and charm. And lets not forget electron, muons and taus too. ...
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Can you have a leading quartic gauge vertex in the standard model?

Under the standard model, is it possible to have a leading quartic gauge vertex in a reaction? For example, if I have a proton collider to look for the reaction $p\bar{p}\to q\bar{q}g$ (may not ...
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Standard Model Particle Properties

Basic question about the Standard Model: Is it accurate to say that all of the particles defined by the SM can be categorically distinguished entirely by discrete properties (eg, spin, color, charge ...
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What is the Lorentz factor γ value in order to find the Larmor precesion frequency for the electron including the Thomas precesion correction?

I want to calculate the Thomas corrected value for the lab frame of the electron's Larmor precesion frequency using this equation: $$\omega_{s(g=2)}=\frac{e B}{m c \gamma}$$ I don't know what Lorentz ...
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Does "lifetime of up quark" have a physical meaning?

I saw this question about the lifetime of an up quark. As far as I know, free quarks are never observed in experiments. Then what is the significance of a statement like "the lifetime of an up ...
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What particles are thought to have existed before Inflation?

What fundamental particles do most Grand Unified and Inflationary theories predict existed before the Inflationary period? Basically, what do we expect the family of particles existing during the ...
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Why is the hadronic $\tau$ branching ratio into 2 pions prefered?

In the PDG the $\tau$ branching ratios are listed and Br$(\tau^- \rightarrow \pi^-\pi^0 \nu_\tau)\approx 25$ %, while Br$(\tau^- \rightarrow \pi^-\nu_\tau)\approx 11$ %. How can this be since the ...
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If quarks are in fact made up of smaller particles, would we ever be able to find evidence for them? [closed]

Disclaimer: I'm not trying to suggest that quarks are made up of smaller particles. This is just a "What if?". We've had to infer the existence of quarks through the behavior of hadrons in ...
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Are Particles Necessary?

I started my reasoning from a curved spacetime: in the description of General Relativity, the universe is a continuum and we get to the Einstein Field Equations. Space and time may or not be ...
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The composition of electrons, quarks and gluons: something or nothing? [closed]

It is told that electrons, quarks and gluons are indivisible thus have no compositions like any particles. So, are they actually composed of nothing or space?
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How can a particle without mass be useful?

person rather new to physics here, and I just started on a rather simple book on particle physics, but I was flustered to learn that there are particles without mass enforcing the fundamental forces (...
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What is the apostrophe I see in HEP articles? (NOT antiquark)

I keep seeing references to quarks as q, and antiquarks as qbar, but I'm also seeing things like q' and q'bar. I originally thought it was another form of notation for anti- but it doesn't appear like ...
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Do the quark types differ from each other in ways other than charge and mass?

I've read things online here and there that seemed to hint that there's more to quark type than mass and charge. Is this true? For clarity's sake, I'm not asking about properties individual quarks ...
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Is it scientifically possible that “DNA can open wormholes” as suggested by an article in a mainstream & reputed journal?

I am attaching the links of two articles: Mathematic model for vibration behaviour analysis of DNA DNA Phantom Effect In the introduction section of the first article it mentions that Poponin tried ...
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What is the maximum spin of a particle? (Both theoretically and observed)

I know that the elementary fermions are spin 1/2 and the elementary bosons are spin 1 (except the potential graviton), but are what is the highest known spin of any elementary particle (including ...
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Why can't I assume the quarks inside a hadron move together?

Looking at the following Feynman diagram: Using conservation of energy, we can see that in the rest frame of $D^0$, the energy of $K^-$ is higher than its rest energy. Meaning, it is in motion. I ...
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Why isn't electron spin a real rotation? [closed]

When an electric current flows, a magnetic field is created. Then, isn't the magnetic field of a magnet also caused by an electric current?
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Why isn't an electron a black hole? [duplicate]

My late night thoughts brought me to a question: If electrons are point particles, but have mass, why aren't they black holes?
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Do particle decays with different products have different decay rates?

https://en.wikipedia.org/wiki/Particle_decay#Probability_of_survival_and_particle_lifetime lists the mean lifetime of particles. But particles may decay in different ways, so is the mean lifetime the ...
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Why does the electron not spin? [duplicate]

The goto answer to that question is that the electron is a pointlike particle and cannot spin. The electron is not pointlike though. It is described by a wavefunction. One can prepare the wavefunction ...
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