Questions tagged [particle-physics]
Particle physics is the study of the fundamental forces of nature as they are embodied in the interactions of elementary and composite particles at high energies and short time and distance scales. DO NOT USE THIS TAG for point particles in classical mechanics.
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What happens when an anti-electron collides with a neutrino?
What happens when an anti-electron collides with a neutrino? If something does happen, is a photon released after the collision?
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How to find projects to work on in hep phenomenology? [closed]
I'm currently a Phd student in particle physics phenomenology and all the projects that my advisor suggests do not seem to cater to an actual need/gap in the literature; specifically, it boils down to ...
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If a $J/\psi$ decays to an electron-positron pair 5% of the time, how often would a $\phi$ meson decay to a electron-positron pair?
I know the mass of $J/\psi$ to be 3097 mev and the mass of phi to be 1018 mev. I know that $J/\psi$ decays to electron and positron 5% of the time. I also know the full width of j/psi to be 0.092mev ...
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To understand modern concepts in the field of Neutrino physics and the field on the whole what are the mathematical prerequisites that I need? [closed]
I want to start working in the field of Neutrino Physics but I am not mathematically well equipped, and I cannot bypass this as it is crucial to the field, what mathematical topics or concepts should ...
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What does it mean to probe a certain energy scale?
For example, what does it mean that the LHC probe the electroweak scale, $M_{EW} \sim 10^3 GeV$? Also why is this energy called the electroweak scale?
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Mass of different isospin baryons
Why are the masses of baryons (of same quark content) with different isospin, different? - Is there a physical intuition/explanation to this? Does higher isospin baryons always higher mass than lower ...
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Why is the decay of the positive Kaon into two Pion more likely than decay of the positive Kaon into three Pion?
I was wondering if someone could explain me (or introduce me a reference) about my following question:
Why is the decay of the positive Kaon into two Pion more likely than decay of the positive Kaon ...
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$\Sigma^0$ baryon decay
I’ve seen it stated that the sigma baryon $\Sigma^0$ only decays to $\Lambda^0 \gamma$, and then $\Lambda^0$ decays to $p\pi^{-}$ or $n\pi^0$.
I understand that the weak interaction conserves weak ...
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Does CERN produce more matter than antimatter?
CERN's LHC has seen matter-antimatter asymmetry, such as CP symmetry breaking and $B_s^0$ meson decay.
The universe produced about 1 part per billion excess of baryons over anti-baryons. My ...
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When do pairs of quarks form jets vs mesons?
For certain processes with low momentum transfer, such as the Kaon decay shown below, quarks will form bound states of mesons.
Whereas for higher momentum-transfer processes, such as the decay of an ...
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Collision between Hydrogen atoms [closed]
Two H atoms in the ground state collide inelastically. The maximum amount by which their combined kinetic energy is reduced is
(a) 10.20 eV
(b) 20.40 eV
(c) 13.6 eV
(d) 27.2 eV
I think maximum energy ...
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Calculating semi-leptonic tau decays in RPV SUSY
Consider, Pion -> electron + neutrino.
I've addressed LQD term, need assistance with scalar current in LLE term. Look at the term, i'm stuck:
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Do virtual particles share the same property values with the normal particles? [duplicate]
For example does a virtual electron have the same characteristic intrinsic values like mass, charge, magnetic moment etc. as a normal stable electron? Or can these range wildly and not having specific ...
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Measurements on a GHZ quantum state for three entangled oscillators [closed]
Consider a system of three harmonic oscillators in the state described by the
vector $( |GHZ\rangle = \frac{1}{\sqrt{2}}(|000\rangle+|111\rangle) )$ where $( |nml\rangle )$ stands for $( |n\rangle |m\...
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Are particles capable of infinite subdivision? [closed]
Are the most fundamental particles, e.g., bosons, fermions, etc., capable of further subdivision? Are they at their most fundamental? Or do we consider them so because we're just not capable of going ...
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How to calculate or estimate an energy deposition inside $\rm BeO$?
I wonder how one could or would calculate the energy deposition inside e.g. $\rm BeO$. To simplify the radiation source shall be a photon with 160 keV and $\rm BeO$ is 0.5 mm thick and 1 mm² wide.
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How charge interact with mass? [closed]
If mass does not interact with charge, why does the mass of an electron move (means by which mechanism it moves) in an electromagnetic field? It is same like we stick ball on magnet with fevistic and ...
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Effect of Basis transformation on a matrix [closed]
I have a matrix:
$\begin{pmatrix}
C_{kk} & 0 & C_{rk}\\0&C_{nn}&0\\C_{rk}&0&C_{rr}\end{pmatrix}$
which is written in the helicity basis {k,n,r}. I want to transform this matrix ...
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Can $W$, $Z$ and Higgs Bosons be also regarded as the first ever virtual particles experimental verified?
With a mean life time of E-25s for the $W$ and $Z$ Bosons and E-22s (predicted) for the Higgs boson nobody has directly observed these particles. Actually their life time is within the Heisenberg ...
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Energy of $B$ meson in a average travel [closed]
The $B$ meson has a mass energy equal
to about 5.3 GeV and a mean lifetime
of about 1 ps. With what energy do B
mesons need to be produced if they are
to travel an average distance of 1 mm?
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The fractional energy loss of charged particle per radiation length
I have a hard time understanding the "fractional energy loss" of the charged particle, as shown in the figure below.
The figure usually has a caption that goes like this: "Fractional ...
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Why do the subatomic particles like electron exhibits Dual-nature? And how does the particle knows when to change their state? [duplicate]
As we all know, Subatomic particles show dual-nature when observed but why? why does this happen? also I am genuinely confused as to how does the particle know when to change its nature, I mean i know ...
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Electron Muon Scattering
I have been doing studying in advance for Dirac Equation and stumbled upon the math on calculating the spin-averaged amplitude $\bar{M}^{2}$ for the electron muon scattering process. Below is an ...
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Why is the lifetime of $\phi$ meson much longer than $J/\psi$
So the mass of $J/\psi$ is 3096Mev while the $\phi$ meson is 1018 Mev and yet the phi meson lives 50 times longer than $J/\psi$ meson. I dont understand why this is, can anyone explain why?
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Why do we need the resonance condition in a cyclotron?
I am currently reading Physics by Halliday, Resnick, and Krane.
In Chapter 22 about elementary magnetism, there is a discussion about cyclotrons. In particular, it mentions the importance of the ...
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Can we regard metric as the Higgs field of gravity?
The longer version of the question is: should we regard special relativity just as a spontaneous symmetry breaking phase of general relativity, driven by the non-zero vacuum expectation value (VEV) of ...
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Are electrons and positrons part of a family of 4 (8? 16?) similar particles?
EDIT: Completely rewritten because of the 'needs clarity' tag and some useful related questions appearing in the side-bar. I hope this is clear now
This answer gives a long list of properties of ...
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Reducing Inelastic Electron-Proton's Scattering Cross Section to Rosenbluth's Formula
I'm currently studying electron-proton scattering from Halzen & Martin's book (Quarks & Leptons : An Introductory Course in Modern Particle Physics). I found that the cross section for the ...
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How to find the tension in the string for given system? [duplicate]
SYSTEM :A uniform rod of mass m and length 2l lies on smooth horizontal surface. A particle of same mass m is connected to string of length l, whose other end is connected to rod. Initially string is ...
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How relevant is the electric charge of quarks within hadrons?
Given that each quark flavor has a particular electric charge (i.e., either +2/3 or -1/3): how do these charges effect the internal dynamics of hadrons? Do the attractive and repulsive effects of ...
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How would I estimate the partial width for the decay of upsilon meson into an electron-positron pair?
I cam across a question that stated the total decay width for the phi meson was 4300 kev and the partial decay of it into an electron-positron pair was 1.3kev. How would I estimate the partial width ...
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Does solid angle of a detector depend on its depth?
Is there any dependance of solid angle on depth of detector.
I just know that $\Omega=\frac{Area \ of \ detector}{(sample \ to \ detector \ seperation)^2}$
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Is it possible for an electron and antimuon to neutrinos?
If i have an electron and an antimuon is it possible that they could annihilate into a electron neutrino and antimuon neutrino? Am i correct in saying both spin and charge are conserved in this ...
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I was wondering if it was possible to make a homemade particle accelerator, and if so, how? [duplicate]
I was wondering if it was possible to make a homemade particle accelerator and if so, how would I?
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Effect of Gravitational Field During Anti-Matter/Matter Collision
This may be a very basic question, please excuse my lack of knowledge but I don't seem to understand the concept of anti-matter gravity.
Upon research, many sources align with the conclusion that anti-...
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What are the main differences between metastable and virtual intermediate states?
I'm studying energy transfer and upconversion processes. The process of ground state absorption followed by excited state absorption involves a metastable intermediate state, whereas a process of two-...
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Considering subatomic particles constantly appear and disappear, can we say everything around us does too?
I'm very inexperienced in this area and could use some guidance, so I would really appreciate it if you could help satisfy my intellectual curiosity. I've come across the concept that subatomic ...
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The displacement for Hertz Contact theory
Hello I just begin to learn Hertz contact theory and have some questions about the geometry of the contact between the sphere and the plate in the figure below.
The displacement $w(r)$is
$$w(r) = \...
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Why does the Matter Anti-Matter imbalance require breaking CP symmetry? Why can't it occur if time symmetry is broken?
I understand the general argument that, without some breaking of symmetry, all the matter in the universe would annihilate all the anti-matter and we'd be left with nothing but photons and some other ...
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Is there a clean mathematical way to deduce grand unification from string theory?
The question says it all. Simply stated:
Can one prove grand unification from string theory?
What is the argument chain of such a proof?
The textbooks I read so far only appear to give hand-waving
...
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Proof that Bjorken-$x$ is positive
For a $t$-channel deep inelastic scattering process the Bjorken-$x$ is defined as:
$$x=\frac{Q^2}{2p_2\cdot q},$$
where $Q^2:=-q^2$ [in the $(+,-,-,-)$ Minkowski sign convention], $q$ is the ...
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What is the colour of an atom? [closed]
We know that when an electron jumps from shell to shell it produces light waves which produce the sensation of vision to our eyes. But can anything be said about the colour of an atom in particular. ...
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Why not put the anti-quarks in the conjugate representation?
The isospin doublet consisting of $u$ and $d$-quark is defined as
$$
\begin{pmatrix}
u\\
d
\end{pmatrix}.
\tag{1}
$$
But the isospin doublet consisting of the antiquarks, $\bar{u}$ and $\bar{d}$, is ...
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Kinetic energy of quarks in a proton
If we say that a proton has a kinetic energy of 50 GeV, can we say that each of the three quarks that compose it have roughly a mean energy of $\approx \frac{50}3=17$ GeV?
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Is there a spin-1/2 hadron composed entirely of up quarks? [duplicate]
I am curious to know if there exists a spin-1/2 hadron that is composed of three up quarks. I understand that in quantum chromodynamics, baryons are formed of three quarks, each carrying a distinct ...
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Conservation of momentum with antiparticle annihilation
I'm confused about how momentum can be conserved when a particle and its antiparticle collide. For example, if an electron and positron collide and annihilate to form two photons, then there should be ...
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Is quantum spin intrinsic, or a function of some other characteristic? [closed]
In my current understanding, I have been told that the spin of quantum particles is simply intrinsic to them. That, particles are simply right-handed or left-handed... just because they are. To me, ...
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Neutrino oscillations and neutrino mass measurement
At the KIT they have been measuring the mass of the electron neutrino with a huge spectrometer (i.e. they make an enormous effort) and already published limits on the highest possible electron ...
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Does a lump of baryonic matter have a well-defined particle number?
From reading about quantized electromagnetism, it seems that many forms of light (e.g. lasers) don't have well-defined numbers of photons, or in other words are superpositions of different number ...
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What is the optimal measuring time split for limited measuring time between signal+background and background in a Poisson counting experiment?
I’m trying to figure out the best split of time between measuring either background or signal+background in a counting experiment in the case where we have no prior knowledge about the mean signal ...
