# Tag Info

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But what we never seem to see is why the electron and positron move the way that they do. Saying "they move like they do because of the force on them" doesn't explain anything at all. It's a non-answer. The equation of motion for charge particle (electron,positron) in magnetic field is $$m\frac{d}{dt}\left(\frac{\mathbf ... 8 If you mean actual photons, the particle gets pushed. Photons have momentum that points along their direction of travel. You may be confused because you might have heard that the electromagnetic force comes from the exchange of photons. So if charges throw photons at each other, it looks like they should only be able to repel, and never attract. The ... 5 The creation of particles has to respect a number of conservation laws. For example charge has to be conserved, so it you create an electron with a charge of -1 you have to create a particle with a charge of +1 to balance it out. Likewise lepton number is conserved (in the Standard Model at least). An electron has a lepton number of +1, so if you create an ... 4 ALICE is a heavy ion experiment at CERN. Here is a lead lead collision One of the LHC's first lead-ion collisions, as recorded by the ALICE detector. Thanks to the advances of computing the vertex is determined by the tracks , measured and pointing back to it, even though there are thousands of tracks from each vertex. Certain tolerance assumptions ... 4 It should be clarified that the Higgs boson does not carry mass. The correct statement is that the Higgs field (not boson) is giving mass to some (not all) particles. In fact most of your mass is not given by the Higgs field. Most of the mass of atomic nucleus (protons and neutrons) is due to the binding energy of strong interaction. The Higgs field is ... 4 As mentioned in the OP quarks vastly simplify the theory of hadrons, like atoms did chemistry, and despite confinement Rutherford-like experiments were performed for them too, by Friedman, Kendall and Taylor who received the Nobel prize for it in 1990: "unexpectedly large numbers of electrons being scattered at large angles provided clear evidence for the ... 3 https://en.wikipedia.org/wiki/Cabibbo%E2%80%93Kobayashi%E2%80%93Maskawa_matrix$$ \begin{bmatrix} d^\prime \\ s^\prime \\ b^\prime \end{bmatrix} = \begin{bmatrix} V_{ud} & V_{us} & V_{ub} \\ V_{cd} & V_{cs} & V_{cb} \\ V_{td} & V_{ts} & V_{tb} \end{bmatrix} \begin{bmatrix} d \\ s \\ b \end{bmatrix} $$The d,s,b quarks are eigenstates ... 3 In classical electrodynamics, charged particles radiate electromagnetic waves when accelerated. An electron in a circular orbit has radial acceleration. Think about where the energy of the electromagnetic waves could possibly come from, and you'll have your answer. 3 The short answer is that what you are proposing would be an extraordinarily challenging task! Simulating a single (non-hydrogen) atom accurately in time requires a huge amount of computational power which scales as roughly (simulation resolution)^(3*number of particles)! In computational biology, nearly all simulations are Newtonian based to avoid this. I ... 3 There are two factors at play here. The Lorentz force which causes the paths to bend with a radius proportional to the particles velocity and with a sense that dependent on both the particles charge and the direction of the particles velocity. In high energy (compared to m_e events) such as the one pictured, the particles are nearly co-linear at the ... 3 Massless particles can carry and do carry confined charges (gluon in QCD) and they may carry charges under spontaneously broken generators (photon is transforming e.g. under the generators of SU(2) associated with the W-bosons) but they cannot carry charges under unconfined U(1) force like electromagnetism. The reason may be explained in different ways. ... 3 It's possible to detect neutrinos in whichever flavor they are oscillating through, so that won't necessarily cause a "dropped packet" problem. The answer is, technically, yes, there is no physical law preventing the use of neutrinos as a communication medium. It has been demonstrated that we can cause the emission and detection of neutrinos. For example, ... 3 For a real answer, each particle would have to be discussed individually and that might get long. Dark matter possibly being Neutrinos has certainly been proposed and in many ways, Neutrino's lack of interaction makes them a good candidate, as they are essentially "dark" - though "invisible" is perhaps a more accurate term and Neutrinos fly through stuff ... 3 You should work out the minimum energy state of your system (classically) to find the vacuum expectation value. I assume you're working with the standard \phi^4-Lagrangian$$\mathcal L=\frac{1}{2}(\partial \phi)^2-\frac{1}{2}m^2\phi^2-\frac{\lambda}{4}\phi^4 $$which corresponds to the Hamiltonian$$\mathcal ...

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To get an understanding on quantum field theory issues, you have to understand the difference between virtual particles and real particles. Virtual particles, in contrast to real particles, are a mathematical construct inspired by the Feynman diagrams used to describe interactions. These diagrams start with real particles, i.e. particles that have the mass ...

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I found my answer, the Higg's Boson is predicted to have a mean lifetime of 1.56 x 10-22 s.

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Fundamentally it is that the $1/N!$ for the classical system only correctly compensates for overcounting of indistinguishable states if the particles are always in different states. For a system of Bosons at low temperature, where it is quite likely that many particles are in the same state, this breaks down. For a very understandable introduction to this ...

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Once one specifies a quantum field theory, typically in the form of a Lagrangian density, one can calculate the probabilities of various outcomes in collisions. A quantum field theory is a theory based on fields that obeys quantum mechanics and special relativity. The so-called Standard Model is perhaps the most famous quantum field theory, and certainly ...

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You have surely seen slit experiments, where waves which pass through the slit and scatter to produce a pattern on a screen placed behind the slits. In the far-field approximation (also known as Fraunhofer diffraction) this pattern is precisely the Fourier transform of the slits. Perhaps you even remember that waves passing by lines produce the same pattern ...

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To answer your questions: Yes, fibreoptics transfer light. Maybe. I'll discuss that now Fibreoptics are strands of glass, they're CRAP at going around corners, I mean seriously crap, communications fibre is VERY THIN. Even then it can't go around bends well, they test it at every stage during laying. However with communications stuff the path matters ...

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To get to an expression to use, first note that the "WI" is for "Weakly-Interacting", which tells you that you should expect cross-section similar to those for neutrinos. That means small, so you can treat a WIMP gas as dilute almost without worrying about it's actual density. So, taking the RMS velocity of on of the particles to be $v_{RMS} = ... 1 If a particle either "is" or "isn't", then its count is either 1 or 0. Even in quantum mechanics it's not possible that half a particle exists. It is possible to detect it with 50% probability, but if you set about counting all the particles one at a time, you necessarily end up with an integer answer. 1 What you propose is called nuclear democracy, and was very popular in the days before the standard model emerged. See also the discussion in http://www.physicsoverflow.org/22971 , where you can read about (among others) my present view of it. 1 Strangeness isn't conserved->Weak decay. As for parity conservation, weak decay CAN change parity, it doesn't have to. Basically, knowing that something IS conserved doesn't give you any information, but knowing that it isn't conserved may give you some. (e.g., electrical charge being conserved means nothing, but it being not conserved means this decay is ... 1 According to wikipedia, Vanadium-48 decays via$\beta^+$(positron emission) to Titanium-48, which is a stable isotope. The emission of neutrons for Vanadium-48 isn't allowed becuase it doesn't conserve energy: Vanadium-48 has a mass of 47.9522537 u, and Vanadium-45 plus 3 neutrons have a total mass of 44.965776 u +3·1.00866491600 u = 47.991770 u. For a ... 1 The mathematics of general relativity is clear and unambiguous. The trouble comes when you try and describe what is going on it non-mathematical terms, because there is no precise way to do it. Kip Thorne is attempting to talk about black holes in non-mathematical terms, and he is adopting a different perspective from (probably) most of us. That doesn't mean ... 1 Very hard to tell without knowing how the spectrum was produced (type and size of the detector, resolution, anticompton, ...). Anyway 180 counts do not seem so many. The single escape peak is normally weaker and the double escape even more, especially if you are just above the pair production threshold. Sounds reasonable that you may not have significant ... 1 Protons and neutrons are extended object, being roughly$1\,\mathrm{fm}$in radius. Give or take a bit, depending on how you want to define their size. Evidence for this comes in three basic forms: first from scattering experiments in which we bounce other particles off of them (electrons are particularly good for this applications); second from packing ... 1 We usually say that in geometric optics we use the "ray model", which is neither the particle model nor the wave model. Given that particles (subject to no forces...) travel in straight lines and that "light rays" go in straight lines when they are moving through a uniform medium I suppose one could say that the light rays look like particle trajectories. ... 1 The states of charmonium are treated as bound states of a charmed quark ($c$) and its anti-quark ($\bar{c}$). Since the binding energy of the$c-\bar{c}\$ system is relatively small, compared to the rest energy of the charmed quarks, it is a reasonable starting point to analyze the states using the non-relativistic Schroedinger equation with a potential ...

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