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# Tag Info

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Yes, there are charged spin zero particles namely the charged pions. However, they are not point particles but rather have a radius comparable to that of a proton. None of the mesons and hadrons are. Only the leptons, the photon, the hypothetical gravitons are point particles. I am not sure of the status of the Higgs boson.

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Why aren't Delta and Omega particles stable? It is a general rule, that a quantum mechanical state decays to the lowest energy level allowed by conservation of energy and quantum numbers. In the case of the Delta the lowest energy state is the proton, because it can decay to it via the strong interaction, conserving baryon number. In models beyond the ...

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Delta half lives are around $5 \times 10^{-24}$, which is 11+ orders of magnitude less than nanoseconds. They are so short that one generally discusses the width ($\Gamma$) of the resonance, given in terms of the mean life ($\tau$) by: $$\Gamma \tau \approx \hbar$$ Deltas are the 3/2-isopin version of the 1/2-isopspin nucleon, roughly and excited state, ...

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They do form, but don’t last long. Delta baryons can have three up quarks (for the $\Delta^{++}$) or three down quarks (for the $\Delta^-$). These baryons are unstable and last only a few trillionths of a trillionth of a second.

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A question whose answer would only moot the real answer to the real question underlying it. The strong interactions preserve parity, so it is a good quantum number for the strong interaction of hadrons; and charge leptons, when considering their electromagnetic interactions, also preserving parity. While the parity of the pion and the electron are well ...

2

All particles have an antiparticle, their transform under C. You may be asking "when is a particle's antiparticle it itself?" Dirac Fermions cannot be their own antiparticle, as their corresponding fermion number transforms nontrivially under C; this then applies to all types of baryon, lepton, etc numbers. Majorana fermions can. They are their own ...

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The set of all gluons contains the antiparticles of each member of itself. But while there is only one photon which is own antiparticle (it is a singlet), each specific gluon has an antiparticle distinct of itself. But its antiparticle is just another gluon and does not deserve to be called an "antigluon". It is like saying that the $\pi$ meson is its own ...

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because the Higgs field interacts with particles to give them mass and does not affect the charge The Higgs field does not interact with particles in the definition of interaction for elementary particles. Particles are the effect of creation and annihilation operators on the fields defined over all space for the elementary particles seen in the table of ...

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At electroweak symmetrybreaking, three components of the Higgs field are absorbed by the SU(2) and U(1) gauge bosons (Higgs mechanism), and become the longitudial component of the (massive) W and Z bosons. The Z boson is EM neutral. The remaining EM neutral component of the Higgs field can manifest as the Higgs boson which is EM neutral too. In the ...

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It's more of a mathematical tool rather than some physical interaction. To see what the maths is, we try and use the Higgs mechanism on a very simple case, which will be an abelian $U(1)$ gauge theory, and you will in the end see where the mass comes from. The $U(1)$ invariant kinetic term of the photon is: $$\mathcal{L}_{kin}=-\frac14F_{\mu\nu}F^{\mu\nu}$$ ...

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The Higgs mechanism is not an interaction. It is a mathematical method of giving mass to the gauge bosons of electroweak theory, because in the laboratory, in contrast to the photon, they are massive. To understand how this works beyond the popularized narrative, one has to study quantum field theory. The standard model of particle physics uses the ...

1

The number that comes after the "$\pm$" sign, is the uncertainty in the value (commonly the standard deviation for Gaussian distributions, for other distributions other measures are usually given, Lorentzian distributions for example, have undefined standard deviation and usually use the full width at half maximum). The difference between the values (means) ...

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Actually, most physicists agree with me about this, the term "force" is not well defined in strong and weak nuclear forces. Really we have four interactions, and of those four, the EM and gravity interactions produce the classic EM force and gravitational force at low energies/large distances. But the weak and strong interactions have no equivalent ...

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Strong hypercharge is a "practically obsolete" global symmetry of the strong interactions, which conserve it: they don't change flavor. It is basically a zero-point shift in the association of $T_3$ with charge, via the Gell-Mann−−Nishijima formula, $$Y=2(Q-T_3).$$ So, beyond the first generation, it is but a plain reader of twice the charges of the ...

1

I can answer "How we know", because I (and others) personally did (one of) the experiments. We had a machine (the Large Electron-Positron collider - LEP) that could apply precise amounts of energy to the centre of a particle detector (in our case ALEPH). As we tuned the energy, we could watch $Z^0$ bosons emerge and decay. The rate of production varies as ...

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You'd best read up on the classic texts by Gasiorowicz Elementary particle physics ISBN-13: 978-0471292876, Ch 17; or Greiner & Mueller QM Symmetries Ch 7, etc, or else WP and also. The rep D(p,q) built out of p triplets and q anti triplets will have a (provably unique!) maximum $T_3$ state $|M\rangle$ s.t. $T_+|M\rangle=0$ with obvious maximum ...

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Photons are neutral bosons, they are their own antiparticle. Seen another way, the photon can be considered as its own antiparticle (thus an "antiphoton" is simply a normal photon). https://en.wikipedia.org/wiki/Photon Neutrinos are fermions, they do have antiparticles, with opposite lepton number and chirality. https://en.wikipedia.org/wiki/Neutrino ...

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You might wish to move or repost your question to HSM where such issues are discussed. Indeed, the Weinberg-Salam model did not figure at all in the historic GIM paper, 1970, not even as a reference. What is required for the suppression of FCNC is a "conventional mixing" of charged currents, reasonably well understood at the time. (Now, Glashow and ...

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Leaving out irrelevant parts, $\bar u ' \gamma^\mu\tau_3 u$ is a "piece" (the third component) of an isovector $\bar u ' \gamma^\mu {\boldsymbol \tau} u$. You have built this isovector (triplet rep) out of two isospinors (doublet reps) u, which transform under su(2) via 2×2 generator matrices, like the ${\boldsymbol \tau}/2$. In turn, the isotriplet you ...

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In natural units, seconds and gigaelectronvolts (i.e., time and energy) are inversely related. You cannot convert GeV to seconds, but you can convert GeV$^{-1}$ to seconds. The value of the reduced Planck constant is $$\hbar=1.055\times 10^{-34}\text{ J}\cdot\text{s}=6.582\times 10^{-25}\text{ GeV}\cdot\text{s}.$$ If you use units where it is $1$, then ...

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