# Tag Info

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The mass of a particle depends on the strength of the Yukawa coupling between the Higgs field and the quantum field for that particle. In the Standard Model the Yukawa couplings are free parameters i.e. their values have to be put in by hand to match the observed particle masses. You ask why the electron interacts with the Higgs less than the top quark, and ...

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There are lots of ways to make antimatter "naturally". One of the most common is pair production. A high energy photon is converted into a particle / anti-particle pair. For example, a photon with energy greater than about 1 MeV ($E > 2 \, m_\mathrm{electron}c^2$) can turn into an electron positron pair (some more considerations are needed to conserve ...

3

While a very important question, I don't think my answer can do much justice in attempting to explain a gargantuan open problem in theoretical physics. But I can give you some overview and point you in the right direction. As of now, everything is work in progress. There are a lot of issues with the standard model which current experimental data cannot ...

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Actually, i would think you are rigth, too. Usually, such a Problem is described via the Bethe-Bloch Formula. If you do an alpha-particle experiment, you can even measure the attenuation of alpha-particles in air, for example. So maybe he meant something else and just put it queery?

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About half of the proton's momentum is carried by the valence quarks (uud) and the rest is spread around many gluons and many sea-quarks ($q\bar{q}$ pairs). In the Drell-Yan process, it is assumed that the colliding quark is a valence quark and the anti-quark must be a sea quark. We are colliding a highly energetic quark with a low energy anti-quark. This ...

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I won't attempt to answer your (rather broad) question in full generality, but address one particular aspect I've learned about recently. You mention that you've heard a little bit about the AdS/CFT correspondence: Although the "classical" AdS/CFT correspondence relates gravity to $\mathcal N=4$ $SU(N)$ super Yang-Mills theory in the large $N$ limit, there ...

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"What general features of particle physics are derived/replicated by constructing string models of particle models?" All of them. Essentially every field-theoretic property or phenomenon of the standard model, has a string-theoretic realization. "How do such models address the fixing of free parameters like the masses and the coupling constants in the ...

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Since in Standard model this problem - why there is the hierarchy between fermions masses - is unsolved (but we may just state that the hierarchy exist, and the reason isn't relevant; this question is like the question about the nature of chiral structure of the Standard model), we may ask ourself: is this hierarchy natural? On the language of quantum field ...

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Intensity in this context often refers to only the number of alpha particles incident on a unit area per unit time. If you assume that the alpha particles only slow down and none of them are stopped completely, then the number passing through any area does not change with depth and the intensity in this sense is unchanged. Naturally the intensity in terms of ...

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Trackpy is a Python package for particle tracking in 2D, 3D, and higher dimensions. http://soft-matter.github.io/trackpy/stable/ https://github.com/soft-matter/trackpy The Matlab Particle Tracking Code Repository Daniel Blair and Eric Dufresne http://site.physics.georgetown.edu/matlab/ Particle tracking using IDL John C. Crocker and Eric R. Weeks ...

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The quarks have fractional charge not only because of fitting proton and neutron constituents. There is a huge data base of hadronic resonances that gave rise to to the quark model , the standard SU(3)xSU(2)x(U(1) of particle physics. The quantum numbers assigned to the quarks are important, among them the 1/3 and 2/3 charge and the color assignements. The ...

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The photocurrent is the steady state current. Let's take your example and suppose your light source is emitting 10 photoelectrons per second. You can use two frequencies - at the lower frequency electrons travel at 1km/s and at the higher frequency the electrons travel at 2km/s. When you first turn on the light there is a delay before the first ...

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Antimatter, although only in the form of positrons, is produced by many nuclides during the β⁺ decay. I can not get any reliable source, but vast majority of such β⁺ nuclides seem to be artificially prepared in a reactor, so this is perhaps not a truly natural source. Other article, named "Antimatter from bananas" states otherwise. The concentration of ...

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