# Tag Info

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Electron positron annihilations can give mu and tau neutrinos as well as electron neutrinos. For a calculation of the probabilities see for example Mu and Tau Neutrino Thermalization and Production in Supernovae: Processes and Timescales. You might also be interested to read DavidZ's answer to Why does electron-positron annihilation prefer to emit photons?. ...

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Skobeltzyn recounts his research on particle physics in his text "The early stages of cosmic ray particle research". Is has been mentioned in another answer, I found it in the book The Birth of Particle Physics edited by Laurie M. Brown, Lillian Hoddeson in 1985. It looks like he was the first one to try using Wilson chamber to detect tracks of high-energy ...

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You might want to look at D. SKOBELTZYN's paper The Angular Distribution of Compton Recoil Electrons Nature 123, 411-412 (16 March 1929) | doi:10.1038/123411a0; but it is behind a 'paywall' and only a short abstract is available for free. (FWIW, Nature, Lond., 1929, v. 123, No. 3098, p.411) EDIT (11/27/2014): See also: Dimitry V. SKOBELTZYN, THE EARLY ...

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According to Bazilevskaya's Skobeltsyn and the early years of cosmic particle physics in the Soviet Union paper (emphasis mine), Skobeltsyn demonstrated a series of photographs with the cosmic ray tracks at the Cambridge conference presided by Ernest Rutherford on 23–27 July 1928, where they made a strong impression on the audience. The comprehensive ...

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The proton is not fundamental. It is made up of quarks and gluons. It is these constituents that are colliding in the LHC to produce, in your example, a Higgs boson. The quarks and gluons only carry a fraction of the energy of the proton. In addition, the colliding gluons or quarks in general do not have the same momentum. Therefore some of the energy will ...

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If you assume that whatever generates the mixing patterns of quarks and leptons (beyond the SM) has no underlying symmetry and that nature chose $V^{CKM}$ and $V^{PMNS}$ randomly within the set of $3\times3$ unitary matrices, then it is natural to expect mixing between families because the probability of randomly selecting $V^{CKM}=V^{PMNS}={\mathbb 1}$ is ...

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Exactly as you mention in the second part of your post. Leptogenesis takes place at temperatures higher than the electroweak scale $T_{EW}\simeq100\,\mbox{GeV}$. Therefore, heavy neutrinos decay into lepton and higgs doublets, whose fields are still all physical.

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This is misconception that light is some kind of 'mix' of waves and particles. Instead, It actually IS both waves and particles at the same time, you can't separate them from each other. So probably, the answer could be: you see particles as well as waves.

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A field and a particle are two different concepts and it is well that one should separate them. A field can be classified as a scalar field, a vector field, a spinor field or a tensor field according to whether the value of the field at each point is a scalar, a vector, a spinor or a tensor, respectively. For example, the Newtonian gravitational field is ...

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The Higgs Field is believed to permeate the universe, and the Higgs Boson is just an excitation of one of the four components the Higgs Field! The Higgs field needs high amounts of energy to be excited, so when Higgs Boson is "created", its energy level is usually many orders of magnitude higher than the ground energy level of its surroundings, and hence the ...

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It would be physically impossible to be able to "see" light as anything other than a particle (photon). The only time photons, or any other subatomic particle for that matter, can be described as a wave is when we are NOT looking at them.

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The uncertainty in any particular measurement is $\sigma_E$. Resolution for these devices is almost always stated in relative terms as here, but take it like this because it depends on the energy measured. So just multiply by the energy. That is, express your signal in $\mathrm{GeV}$ and then find \begin{align} \sigma_E = \left(\frac{0.1}{\sqrt{E}} ... 55 You are seeing particles. However there's more to this than meets the eye so I need to explain exactly what I mean by this. Light is neither a particle nor a wave. Instead it is a quantum field. As a general rule while light is travelling it appears as a wave, but when the light quantum field is exchanging energy with anything it does so in quanta that ... 2 A) What is the piece of theory which dictates that electrons interact via the weak force with other electrons and protons, and how can this force be understood in terms of what I am more familiar with i.e a coulombic interaction and dipole moments ... Electrons interact via the electromagnetic force dominantly with other electrons and protons, not the ... 0 I think that we may add that in the confining phase, the QCD-string descritpion of quarks (say, mesons, which are bound states of quark/anti quarks) is that these particles sit at endpoints of "QCD-strings" (I use "" to distinguish this from the normal superstring which is a well defined object, though it failed for the moment at describing exactly ... 14 Quarks as we know them are fundamental particles, which means that they do not have smaller constituents. This however does not imply that they cannot decay. A particle in quantum field theory does not need to have constituents to decay into, it can in principle decay into any particle its corresponding field couples to (interacts with), as long as it obeys ... 6 The u & d quarks decay into d & u quarks and bosons (e.g., W bosons)--this is effectively what happens to the hadrons in weak interactions. This (incomplete) chart shows, for instance, u\to d+W^+\\ d\to u+W^- $$There isn't anything sub-quark, as far as the standard model goes. 6 The current understanding of quarks is, that they are a fundamental particle. This means for the energy scales currently available in particle accelerators all quarks have behaved like point-like particles. Due to the strange nature of the color-field (the energy stored in it increases with distance instead of decreasing) if you break a proton apart (which ... 1 Not really, at least not if you want to stay with properties you would normally associate to particles. That is because particles are not the fundamental objects of quantum field theories, but fields.1 There's more to the theory than charges and masses. For every symmetry group of the theory, a field must transform in a representation of it. Now, you can ... 3 In realistic QFT, fields or their interaction law mostly correspond to irreducible representations of some symmetry groups. If we assume free theory, there is only one important symmetry: it's Poincare symmetry (it is the most important symmetry - in flat spacetime each field theory must satisfy it). Poincare symmetry leads to the statement that free ... 2 It basically boils down to the term e^{-\frac i\hbar E t}, where the minus can either be included in the energy, making it negative, or into the time. But a negative charge moving backwards in time is exactly the same as a positive charge moving forwards in time, and that is much more sensible than negative energy. 4 Generally the particles that enter these ionization chambers have such high kinetic energy that they can pass through walls. The gas inside the ionization chamber is not travelling nearly so fast. Kinetic energies of the gas would be at least a million times lower and often much lower than that. The gas cannot escape through he walls. High energy ... 1 I believe that particle physics is a field where to be able to contribute to the field you must have the mathematics. Without them your understanding will be severely limited and in many cases not even wrong. On the other hand it is possible to contribute to physics to in general with no more math than you get in junior high. This is because physics is the ... 1 The link Kyle gives in his comment expands enough on the reasons a) why is there still matter in existence?. That there exists matter as we know it is an experimental observation that has to be taken into account in any theoretical formulation. The existence of matter and antimatter is an experimental observation in the elementary particles data in our ... 0 A positron is an electron travelling backwards in time" said by Feynman. This is the Feynman diagram for electron positron annihilation at low momenta of the electron and positron. Therefore how an electron and positron annihilate producing photons since total momentum is p-p=0 therefore how they produce photon with momentum The diagram is a ... 4 Be careful to compare the same quantity. You ask if gravity (a force) affects the voltage (a potential energy). These are related but not identical. For a first round comparison, check out the forces due to gravity and a standard voltage (1 Volt over a distance of 1 cm): First, the gravitational force on an electron at the surface of the Earth:$$F_g = mg = ...

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The properties of a particle appear, and play a role in determining the energy, when the particle moves in some field. For instance, if it moves in an electrical field, the charge is a relevant property because in an electric field the particle is accelerated or decelerated and it also gets a potential energy. In a magnetic field is important also the spin ...

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Computational chemistry methods have advanced significantly in the last 5-10 years, including much more accurate DFT methods, quantum mechanical dynamical methods (like Car Parrinello MD, and better classical molecular dynamics techniques. That said, dealing with the dynamics of molecular reactions is an active area of research. Perhaps the most promising ...

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It depends on the level of theory you want to apply to a simulation. For example, the current state-of-the-art ab-initio calculations for a single low ernergy ($\lt 10~eV$) electron approaching and interacting with a molecule can cope with perhaps 20 to 40 electrons in the target molecule. Note that ab-initio calculations contain, in principle, no ...

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You do understand that short-range neutrino measurements show the expected flavor mix, right? That is if we set up a detector a few meters from a nuclear core we observe neutrino interactions involving electrons. If we set one up just downstream of a neutrino beam-line we see mostly interactions involving muons (with the expected admixture of those ...

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The best measurement of the neutron magnetic moment was reported in 1979 by Greene and collaborators. That measurement used nuclear magnetic resonance (NMR) to measure the rate at which the spins of polarized neutrons precess around a magnetic field. The magnetic field was measured by flowing water through the same volume as the neutrons and also performing ...

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No collision is possible in between two electrons because the electron carry negative charge and push each other away with some assumption

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Answer to this question is only by understanding and not proof. If the Universe is expanding then I say Yes, to that the Matter is also expanding. Explanation for this is, all the Matter is expanding means, even the scale to measure the Matter is also expanding. Consider a small Example: A rectangular wooden block is expanding, Measure the initial ...

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Yes. In a two-dimensional Yang-Mills gauge theory, the Faddeev-Popov ghosts kill two possible excitations of the gauge field (same as always), leaving no possible excitations that we would characterize as particles. There are no gauge bosons in such a theory. (There are global "excitations" though, analogous to instantons, but they are not particles) Yet, ...

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There may be some problems with Teflon particles. Prior to droplet separation from the syringe, the Teflon particle can roll down along the surface of the droplet, so you'll only have your tracer at the bottom of the droplet. This movement of the particle along the surface will not take place when the droplet is in free fall. This movement will be less ...

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I would consider using water with a dye like a deep blue to be nearly opaque. Illuminate with an array of LEDs. Each bright spot reflected from the droplet is an LED. You can add a few strategic red LEDs among all white as reference. Working out the most convenient geometry will tell if you need the LEDs on some curved surface in space or if a flat panel ...

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A different angle on this that I DON'T believe is in conflict with Terry Bollinger's answer: whether you express a wavefunction in position co-ordinates, or, as its Fourier transform, i.e. in momentum co-ordindates, the two models are precisely the same. So neither the expression of a position co-ordinate wavefunction (such as you find from the solution of ...

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A pure plane wave is not a physically realizable state for a real particle because it would require the particle's wave function to extend over infinite space. Even if the universe is open and infinite in size, it has only existed for a finite time, so no particle wave function would have had enough time to grow to infinity.

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Do you remember how spiderman originally go his powers? Or the Hulk? Spiderman was bitten by a radioactive spider and Bruce Banner (the Hulk) was bombarded by a large amount of gamma radiation. These were superhero characters created in the advent of the age of nuclear power at a time when the average person didn't much understand what radiation was. Today, ...

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First of all particle accelerators (LHC for example) have a lot radiation packed into it perhaps enough to kill you pretty quickly. Next, if you think a single proton may give you super-powers your wrong, in space for example astronauts get hit by particles that have many magnitude of more energy than that of LHC beam (most powerful particle accelerator ...

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It can transfer energy to a Human and produce injuries and death - no superpowers.

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