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.

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Mathematical form of the de facto repulsive “force” associated with the Pauli Exclusion Principle [duplicate]

One of the principles of General Relativity is that test objects follow a geodesic unless otherwise acted upon by a force. From this perspective, it is clear that physicists, consciously or ...
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2answers
62 views

Do light particles come in different sizes? [duplicate]

Do light particles come in different sizes if it makes sense to even think about them that way?
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1answer
45 views

Do muon neutrinos have more energy than electron neutrinos?

I saw an answer to "how to identify a muon neutrino and electron neutrino" as being "Weak interaction conserve not only the global lepton number, but the lepton flavor numbers as well. And that is ...
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2answers
37 views

If two very small and smooth particles collide at perfect right angles, is there friction?

If two perfectly round particles collide at perfect right angles, is there friction between them? If so, Is the friction in the form of heat (average kinetic motion), because if it is, where is this ...
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1answer
53 views

How force is transmitted in Magnetic field (Quantum mechanically )

According to particle physics , every fundamental force has its force carrier particle. Photon is a force carrier particle of electromagnetic force but What is the process through which magnetic ...
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1answer
53 views

I want to make something but i have to bend light without a black hole

I am trying to make something that requires a vortex of light, but the only thing i know that can do that is a black hole . . . so is there any possibility that i can make the vortex without a black ...
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4answers
87 views

Can you compress pure carbon into diamonds?

I'm doing a science project, and we're wondering if it is possible to compress pure carbon (C) to the point where it becomes diamonds? What would the process have to be and how much energy would this ...
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0answers
14 views

T invariance in flavored meson system

Consider Kaon CP conjugate states $\left|K^{0}\right>$ and $\left|\bar{K^{0}}\right>$. The physical states i.e, eigenstates of effective hamitonian can be written as \begin{equation} ...
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2answers
60 views

Attracting lightning with an ion beam

Can an ion beam be strong enough to create a path for lightning to travel to the ion machine? This is what I found in a lab that may help: An ionization factor jτi (the product of electron beam ...
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0answers
27 views

Do neutrinos get their mass via interacting with the Higgs Boson? [duplicate]

Do neutrinos follow the Standard Model and get their mass via the Higgs Mechanism or we still don't know about the origin of their mass as neutrinos with mass are beyond the Standard Model?
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1answer
50 views

Leptonic Decay of Muon and Tau

So the question asks: (a) Draw the Feynman diagrams showing the dominant leptonic decay mode of the $\mu^-$ and the $\tau^-$. (b) Assuming $m_\tau \gg m_\mu \gg m_e$, estimate the ratio of the rate ...
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56 views

What is the meaning of thermal spectral function and thermal decay width in thermal field theory?

In Kallen-Lehmann spectral representation of 2-point correlation function \begin{equation} \langle 0|T\phi(x)\phi(0)|0\rangle=\int_0^\infty \frac{dM^2}{2\pi}\rho(M^2)D_F(x-y;M^2),\quad (a) ...
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1answer
79 views

Electron decay in high-energy accelerators

As far as I understand, electrons are infinitely stable since they are the least massive particle with non-zero electric charge. However, when accelerated to high-energies, the energy (or mass) of the ...
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1answer
45 views

Ratio of the total energy of the beta particle to its rest energy [closed]

I'm trying to learn particle physics and I came across this question in which I have no idea on what to do. Help would be greatly appreciated. Uranium-239 decays by emitting a beta particle, to ...
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0answers
29 views

What is the form of Higgs potential, when written using higgs mass and quartic coupling.

Usually we write Higgs potential as $V=-\frac{1}{2}m^2 \phi^2 + \frac{1}{4}\lambda \phi^4$ What are the present reliable values of parameters '$\lambda$' and '$m$'? Is '$m$' used here Higgs mass? If ...
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2answers
99 views

How to interpret the field configuration in quantum field theory?

We often use the Fock space as the start point for our quantum field theory. In the Fock space we have definite physical meanings for the state. For example, the state $$|k_1k_2...k_n\rangle$$ ...
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22 views

Why dark matter do not gather together? [duplicate]

Stars and planets were gathered together by gravity, thus emit light. Why dark matter doesn't behave that way? Why they won't be gathered together by gravity and form stars?
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53 views

$S$-matrix expansion and Feynman graphs for toy model

I have a toy model with three interacting particles $A$, $B$ and $C$ and $A$ can decay to $B$ and $C$. Looking at the process $AB\to BBC$ I just want to know which orders of the $S$-matrix expansion ...
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183 views

Yukawa interaction between Dirac particles is universally attractive?

Can anyone provide me a specific reference to (or supply themselves) the derivation of the fact that the Yukawa interaction$$\mathcal{L}_{\text{int}} = -g\overline{\psi} \psi \phi$$between Dirac ...
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156 views

In a universe with four spatial dimensions would there be elementary particles with intrinsic isoclinic spin?

Elementary particles have an intrinsic property called spin which is different from classical spin as it does not involve actual rotation and the magnitude of spin cannot be changed but particles with ...
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1answer
47 views

Electrons-muons through matter

Do electrons and muons behave differently while passing through matter?Why does this even happen even though both of them are leptons and they can be found in 2 different states due to their ...
2
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0answers
45 views

Would CP Violation happen in a universe with four spatial dimensions?

The weak force is the force that violates CP symmetry as the way it effects a particle depends on that particles handedness. Particles have a property known as spin although it is different from ...
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27 views

$\rho$-parameters for several Higgs multiplets

I'm studying the Higgs mechanism of the spontaneus symmetry breaking in the SM. The expression for the $\rho$-parameter is $$ \rho=\frac{M^2_W}{{\cos^2\theta_w}M^2_Z}, $$ that, in the case of a ...
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1answer
83 views

Gravity goes through everything?

I was thinking about it, the Earth has her gravitational field, but this field comes by the Earth right? Or he just exists around the Earth? If the "gravitons" comes by the Earth, can them goes ...
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2answers
74 views

Does quark confinement imply indivisibility of quarks?

I recently heard the statement$^1$ that quark confinement is evidence for the indivisibility of quarks (i.e. that they are indeed fundamental and have no substructure), but I don't see any reason why ...
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69 views

What subatomic particle is a blackhole composed of?

In a black hole, what is the "state" in which the mass that is present is in? Are they there as tightly packed neutron or soup of quark or are particles broken down into 10D strings and coiled as ...
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2answers
93 views

What does “charge” actually mean? [duplicate]

I know that a charged particle is defined as a particle that experiences a force in an electric field, as explained in this post: What does a subatomic charge actually mean? However, I still don't ...
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21 views

Does matter shrink due to energy radiation and does it have anything to do with dark matter and dark energy?

Is matter shrinking? Is shrinking the cause of concentrated dark matter that makes up matter moving from concentration to unconcentration. Does dark energy and expansion of the universe come from this ...
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1answer
41 views

Fire, catch and fire a particle

To be more specific, would it be possible to perform the stern Gerlach experiment on a single electron multiple times provided that none of the electrons paths were blocked.
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9 views

References on particle cooling

I am looking for references on the topic of particle and mechanical oscillators cooling, in particular: Doppler cooling Resolved sideband cooling and Lamb-Dicke regime Stokes and anti-stokes modes ...
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96 views

Real world applications of post-1950s High Energy Physics [closed]

Imagine a world where people knew everything we know today except for high energy physics, where their knowledge ends at our ~1950s level. Is there any real world application, any particular piece of ...
2
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0answers
69 views

how to analyze the collision of two photons with four-momentum vector? [closed]

Q: If two photons with energies $E_1$ and $E_2$ collide, with their trajectories making an angle $\theta$. Is the following right about individual initial 4-momentums and total initial 4-momentum? and ...
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1answer
59 views

Particles, quasiparticles, and “stability”?

So I'm studying Fermi Liquid Theory, which concerns itself with quasiparticle excitations made by superpositions of single-electron wavefunctions. We create particle-like wavepackets which exist for ...
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1answer
26 views

Positive free particle Dirac equation

I've been set the task of showing that: $$ \bar{\psi^{s}}\psi^{s}=2m $$ For s=0,1. Where: $$ \psi^{0,1}=\sqrt{|E|+m}\begin{pmatrix}\chi^{0,1}\\ ...
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1answer
34 views

Valence sea quarks parton distribution functions

There's somethin from Thomson (Modern Particle Physics) that I am a little mythed by. Section 8.4.3, eq. 8.3 is given as $$ ...
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1answer
31 views

colorless charge in a baryon

In a baryon there are 3 quarks and in a meson there are one quark + one anti-quark. So color charge is colorless ( a color singlet state ) in a meson. But how is it colorless in a baryon ?
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Help - calculation probabilities - new theory [closed]

I need help to calculate exact or approximated probabilities. I am interesting by the content of a new theory (view this link nokton theory for details). Currently, I studing the interactions of two ...
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56 views

How often do quarks annihilate?

How often do quarks annihilate? Quarks bond frequently with quarks, and antiquarks bond frequently with antiquarks. So why do quarks not annihilate antiquarks extremely quickly? More to the point, ...
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0answers
48 views

$SU(3)$ Tensor Methods in a Tetraquark

I am trying to understand the Georgi chapter of tensor methods in $SU(3)$ representations, and I don't know how to resolve the tensor product of 2 matrices in a 2 heavy quark + 2 light antiquark ...
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0answers
33 views

Quark axial-vector current in nucleion

In almost all direct detection articles (see for example Jungman, G., Kamionkowski, M. & Griest, K., 1996. Supersymmetric dark matter) I found the following parametrization for the matrix element ...
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1answer
41 views

How to measure the mass of an uncharged particle like a neutron?

How we can measure the mass of a neutral particles like neutron? To measure the mass of a charge particles like electron we use mass spectroscopy. What about uncharged particles?
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How do we determine total isospin when only third component of isospin is known?

Both $ \frac{1}{\sqrt{2}} (np - pn)$ and $\frac{1}{\sqrt{2}} (np + pn)$ has third component of isospin equal to 0. But the first combination has total isospin equal to 0 while the second combination ...
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3answers
46 views

FWHM increase with energy (gamma spectra)

Below I have two plots from a gamma spectrum which I've been analyzing. The first plot is between a low energy range, the second between a significantly higher energy range. It is clear that the FWHMs ...
2
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2answers
126 views

Has the Higgs boson always existed?

I am slow and need some help understanding this. So has the Higgs boson always existed? If not, than how did it come to exist? What would have excited it before matter or particles were created? So ...
3
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42 views

How does one determine chirality experimentally?

The Standard Model says that only left-handed electrons participate in weak interaction. A very natural question for novices like me is then: How can we tell, experimentally, if an electron is ...
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1answer
37 views

What is the physical meaning of $\alpha$ in this disintegration problem?

I am taking a course where I have to solve the following problem related to the disintegration of a baryon in a proton and a pion $(\Lambda \to p^+ + \pi^-)$: Assume that a $\Lambda$ particle with ...
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0answers
11 views

Kinematic equations of a cascading particle decay

This paper discusses different measurable quantities that can be used to search for unknown particles at particle accelartors. For the following decay it introduces the invariant mass $m_{XY}$: It ...
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1answer
47 views

Particle Physics: Weak Interaction

Consider the following decay equation:- A Kaon(+) decays into a muon(-) and an antineutrino(?) The question is as follows :- State and explain whether the anti-neutrino is an electron, muon or tau ...
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Parametrization of the medium change from solid to gas?

I am thinking the model where the parametrization of GEM (Gas Electron Multiplier) is open. I can reach a high sensitivity in similar systems where the medium is solid such as in solar cells (5 ...
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Speed of an antimuon in a pi meson decay [closed]

I'm trying to confirm the speed of an antimuon in the $ \pi^+ \rightarrow \mu^+ \nu_{\mu}$ decay through the laws of conservation but it doesn't add up. I'm using $m_{\pi} = 139.6 \ \frac{MeV}{c^2}$, ...