Tagged Questions
3
votes
1answer
41 views
Convolving Parton Distribution Functions
I have the cross-sections as a function of $\sqrt{s}$ for a process with a $u$-quark and $u$-antiquark in the initial state (eg.: $u \bar{u} \to e^- e^+$). I have a standard parton distribution ...
0
votes
2answers
127 views
Why is electron presented in books, pictures as a sphere?
Why is electron presented in books, pictures as a sphere, when in fact it's not?
1
vote
2answers
66 views
Does the unpredictability in the “micro world” means that everything is if we can look at it close enough imperfect?
Does the unpredictability in the "micro world" means that everything is if we can look at it close enough imperfect?
I mean, there is a saying "You will never stand in the same river again" or ...
0
votes
1answer
127 views
Is the idea of dividing the universe into particles anything more than an untrue convenience? [closed]
In theory, we speak of a particle as having properties.
In reality, the measurement of any property is just an interaction between the target to be measured, and the measuring apparatus, where the ...
1
vote
3answers
143 views
Do particle pairs avoid each other? Please end my musings
Can you explain what happens when a particle and its antiparticle are created. Do they whiz away from each other at the speed of light or what? I suppose that they don't because otherwise they would ...
6
votes
6answers
561 views
What is the meaning of the word “particle” in particle physics?
I want to use Matt Strassler's definition of the word "particle" as a specific example:
Matt Strassler writes:
(1) "...all the elementary “particles” (i.e. quanta) of nature are
quanta of waves ...
2
votes
1answer
90 views
$sss$ decay and violation of strangeness
Why can the hyperon $\Omega^{-}$ not decay by strong interaction? It seems that strangeness must be violated, but why is it the only way?
1
vote
1answer
253 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 ...
1
vote
1answer
188 views
What was the first discovery of the delta baryon $\Delta^{++}$?
The delta baryons (also called delta resonances) are a family of subatomic hadron particles which have the symbols $\Delta^{++}$, $\Delta^{+}$, $\Delta^{0}$, and $\Delta^{−}$ and electric charges +2, ...
1
vote
2answers
138 views
Why are atoms particles?
The Oxford English Dictionary definition of particle is as follows:
"A component of the physical world smaller than the atom."
I read an article in NewScientist and it said
"...all particles from ...
5
votes
5answers
691 views
The observation of a non-SM resonance at 38 MeV
Was reported here. Of course if this is real it is very exciting. It leads me to the question: given that it took so long to find this resonance at a meager 38 MeV, is it possible that all SUSY ...
4
votes
2answers
193 views
Higgs boson and quasiparticles
Do we know exactly the difference between particles and quasiparticles? Is Higgs boson a particle or a quasiparticle? I ask this because if I understood well, Higgs boson created by a spontaneaous ...
3
votes
0answers
185 views
what interactions would take place between a free proton and a dipolariton?
What interactions can be expected to take place between a free proton and a dipolariton, (a) at high energies and (b) at lower energies?
A dipolariton is a bosonic quasi-particle mentioned in a ...
2
votes
2answers
138 views
How the nucleon structure has been identified experimentally?
It is known that nucleons (proton, neutron) are composed of partons (quarks, etc.). How was this identified experimentally? In particular, how it has been identified that nucleons comprise of more ...
15
votes
3answers
891 views
Are elementary particles actually more elementary than quasiparticles?
Quarks and leptons are considered elementary particles, while phonons, holes, and solitons are quasiparticles.
In light of emergent phenomena, such as fractionally charged particles in fractional ...
1
vote
1answer
154 views
Stability of neutron [duplicate]
Possible Duplicate:
How come neutrons in a nucleus don't decay?
It is known that free neutron decays in 15 minutes on average. Why is it much more stable when "placed" in nuclei?
Edit: ...
7
votes
1answer
268 views
why is there no ninth gluon?
A teacher of mine told me once that there were no ninth gluon because such a one should be white and interact infinitely far, and no one has been observed. Is there also a theoretical reason?
0
votes
2answers
146 views
Speed Distribution of The Particles
I want to know the distribution of the particles's speed.
The particles what I mean are nucleons and electrons of element.
Consume there is 1kg of iron on room temperature and it's shape is sphere.
...
3
votes
3answers
617 views
What is lepton number?
What exactly is a lepton number of a particle? With the charge (eg proton is just 1, not the exact charge), I can understand because it's a physical property, put a particle with charge + next to ...
-2
votes
1answer
207 views
Transition of Electric Charge In Collision Between Proton And Antiproton
I know that
$$p+\bar{p}\to 4\pi^++4\pi^-+(\gamma)$$
Before the collision, the sum of absolute electric charge value is $2$.
$$\left | +1 \right |+\left | -1 \right |=2$$
After the collision, the ...
10
votes
1answer
2k views
Phase shifts in scattering theory
I have been studying scattering theory in Sakurai's quantum mechanics. The phase shift in scattering theory has been a major conceptual and computational stumbling block for me.
How (if at all) does ...
6
votes
3answers
257 views
References on the non-compositeness of the known elementary particles
What paper(s) or theory(s) describe or prove that the elementary particles that we have determined today cannot be made up of smaller more fundamental particles?
4
votes
1answer
728 views
Why does lambda decay violate parity?
When a lambda particle decays into proton and a pion, I am told it does not conserve parity. Why?
2
votes
2answers
2k views
How do alpha and beta particles ionise surrounding particles?
I've been wondering about this question for a while. If you have alpha and beta particles released from a radioactive core, how do they ionise surrounding particles?
