Questions tagged [elementary-particles]
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Nature of Microscopic space-time
I am going through the introductory chapter's of Schwinger's Source theory. He writes,
It [Source Theory] is a phenomenological theory, designed to describe the observed particles. No speculations ...
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1answer
634 views
Lifespan of particles
After reading a very informative tutorial on elementary particles physics over at http://www.particleadventure.org, I have a question I can't figure out.
I understand the need to accelerate a ...
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0answers
157 views
What is the most fundamental peice of matter? What is it that thing which can no more be sub-divided?
I know that there is theory that strings are the most fundamental particles. But if it is a string, then it can be 'cut' into pieces, and if it can be 'cut', then it can be cut at infinitely many ...
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2answers
113 views
Quarks are now considered to be fundamentals, but so were atoms some time ago. So the way we see is only limited by our technological advances? [duplicate]
After watching this FuseSchool - Global Education episode, I cannot stop thinking how can something not have a substructure, how it cannot be split?
http://www.youtube.com/watch?v=nlv06lSAC7c
2
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1answer
2k views
What is the difference between QFT and elementary particle physics?
I'm a little unclear as to how QFT differs from Elementary particle physics. They both use pictorials of Feynman graphs, is it that Elementary particle physics assumes the point particle perspective, ...
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2answers
281 views
Can we make usable energy from subnuclear particles?
I understand mass and energy are the same, but in this question I will be talking about mass being turned into usable energy (electricity/heat/etc). We can make our energy through chemical reactions ...
0
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1answer
178 views
Muons Internal Clocks and Time Dilation? [closed]
I don't get how time dilation affects the half-life of muons? Time is just a tool that is used by humans how does that affect the internal clocks of elementary particles?
10
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1answer
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Explaining chirality for spin 1/2 particle
I found the following explanation for chirality for spin 1/2 particles here
What happens when you rotate a left- vs right-chiral fermion 360
degree about its direction of motion. Both ...
5
votes
2answers
4k views
Is there scale by size of all discovered particles?
Atom:
Neutron:
Elementary particles:
Is there scale by size of all discovered particles?
From neutron and proton to electron and to boson?
Compare to each other, like this
I have found many ...
5
votes
2answers
592 views
Is ch. 2, sect. 4 of The Feynman Lectures on Physics, Vol. 1 still accurate?
The chapter 2 section 4 of volume 1 is on nuclei and particles.
Here are a few things that trouble me. Dr. Feynman says that
Another most interesting change in the ideas and philosophy of science
...
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1answer
392 views
Has the spin and parity of the Higgs boson been experimentally confirmed? [closed]
I read in a newspaper that the Higgs boson might be the new boson but that this was not confirmed, because we don't know its properties, e.g. its spin or parity. Now I see it confirmed that it is the ...
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3answers
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Why are all force particles bosons?
All of the force-particles in the standard model are bosons, now my question is pretty short, namely:
Why are all force particles bosons?
This can't be a coincidence.
5
votes
1answer
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Is it dangerous if one elementary particle with high energy penetrates our brain?
We might be killed if a bullet penetrates our brain. How about an elementary particle moving with high energy penetrates our brain?
Assume that we can have exactly a single elementary particle for ...
2
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1answer
59 views
Asymmetry in muon energies of public CMS dimuon event data
CMS published for educational purposes (caveat) 100.000 dimuon events:
https://cms-docdb.cern.ch/cgi-bin/PublicDocDB//ShowDocument?docid=11583
As one easily sees, column 4 shows the first muon's ...
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11
votes
2answers
2k views
Is everything made of massless particles?
Photons have no mass. Yet they interact gravitationally, as all energy does, with other energetic and massive particles. This means that if you put multiple photons in a system, you get something that ...
0
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2answers
494 views
Elementary (fundamental) properties in electricity
I tend to believe that there are two elementary properties in electricity:
Electric charge
Coulomb's force
I think that I can express any other entity in electricity using just these two (by means ...
7
votes
1answer
415 views
Is color confinement detected?
I'm a graduate student studying QFT. I'm quite interested that is color confinement detected or proved? (both directly and indirectly) Or it is just an assumption?
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1answer
569 views
String theory and the SM spectrum [closed]
Long ago, I realized this: (super)string theory can NOT give a well-defined/unique prediction of why the electron (muon, tau) or the neutrino (any flavor) masses have the masses we measure. String ...
3
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1answer
1k views
Why no fundamental force from the Higgs? [duplicate]
I wish to ask whether I understand the following correctly. This universe seems to have six fundamental elementary bosons namely photon $(\gamma),\ W$-bosons$(W^+,W^-),$ gluon$(g),\ Z$-boson $(Z)$, ...
0
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1answer
203 views
Is everything in the physical world composite?
In philosophy there is a principle that anything composite cannot have existed eternally, since it is preceded by its parts and whatever forces assembled it.
Is everything in the physical world ...
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0answers
333 views
Matrix element approximation
In the formula for the decay width of $\Upsilon(4S)$ to B-mesons from $\text{e}^+\text{e}^-$ collisions:
$$\Gamma_{\Upsilon(4S)\to B\bar{B}}=\frac{\left|\underline{P}_B \right|}{8\pi M_{\Upsilon(4S)}^...
2
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0answers
234 views
Parton Distribution Functions, average cross section of the nucleon
Say we are given the scattering cross section for neutrinos from $d$ and $\bar{u}$ quarks as $\frac{d\sigma^{d}}{dQ^2}=\frac{G_F^2}{\pi}$, $\frac{d\sigma^{\bar{u}}}{dQ^2}=\frac{G_F^2}{\pi} (1-y)^2$, ...
0
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1answer
72 views
Does it happen at high energies (heavier leptons decay)?
A lepton is an elementary particle. The best known of all leptons is the electron which governs nearly all of chemistry as it is found in atoms and is directly tied to all chemical properties.
The ...
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0answers
71 views
Can the mass of a SUSY particle depend on the process it participates in?
I believe that mass is property of every particle,as well as spin etc.Now I'm interested in SUSY particles in cMSSM model.Can it be,that mass of a SUSY particle (at one point in five parameter space) ...
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1answer
97 views
Can objects, animate or inanimate, be constructed out of basic particles?
If all the elements are made of protons, neutrons and electrons, but some elements are much rarer and more expensive than others, would it be possible to break apart atoms of one element and make ...
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1answer
1k views
Definition of elementary particle [duplicate]
Possible Duplicate:
Why are atoms particles?
According to wikipedia an elementary particle or fundamental particle is a particle not known to have substructure.
Moreover, I've learned that such ...
0
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3answers
649 views
Is it true that an isolated fundamental particle does not decay?
Is it true that an isolated fundamental/elementary particle does not decay?
It seems logical to me.
2
votes
2answers
653 views
Parity, how many dimensions to switch?
Parity is described in Wikipedia as flipping of one dimension, or - in the special case of three dimensional physics - as flipping all of them.
Is there any simple rule that generalises both for any ...
2
votes
2answers
2k views
A basic confusion about what is an atom
Wikipedia defines atom as
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons.
and defines electron as:
The ...
6
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0answers
902 views
General equation of motion for elementary particles
Elementary particles can be grouped into spin-classes and described by specific equations, see below:
Is there a general Lagrangian density from which all these equations can be derived?
A ...
