全美高中生组织反枪支暴力集会 白宫发表声明表示赞赏
百度 文/桐城一派西甲第27轮，榜首第一的巴萨和第二的马竞展开了一场关键对决。
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.
18 questions from the last 30 days
-3
votes
0
answers
55
views
Masters course recommendations in Spain or Italy [closed]
I am completing the final year of my bachelors next academic year in Trinity College Dublin in Theoretical Physics, which is a 4 year course which contains courses on QFT, the Standard Model, ...
0
votes
0
answers
28
views
Usage of total cross sections in different reference frames relavistically
I am currently working on calculating the mean free path length of mild relativistic positrons in thermalized plasmas. For example, I want to calculate the mean free path length considering Rutherford ...
1
vote
1
answer
55
views
Does strangeness have $U(1)$ symmetry?
I know that isospin has $SU(2)$ symmetry, meaning one can rotate $u$ quarks into $d$ quarks and vice versa without changing the underlying physics of a system when ignoring the mass difference.
In the ...
- 89
2
votes
0
answers
94
views
What happens when we try to rotate a proton?
Statement: I am well aware that protons are not solid marbles and do not have quadrupole moments. I have read Shapes of the Proton.
I would like to know:
If we attempt to transfer angular momentum to ...
- 199
-1
votes
2
answers
93
views
What is wave nature of particles? [closed]
De Broglie's Hypothesis proposes wave nature for all matter in this universe and calculates the wavelength for this so called "matter-wave".
I want to know what exactly this matter wave is, ...
- 13
1
vote
1
answer
130
views
How does one define the spin of composite particles?
If I understand correctly, the spin of a particle is said to be $s$ if the Hilbert space representing the "internal" (spin) degree of freedom is an irreducible space under rotation with the ...
- 1,747
-2
votes
0
answers
62
views
How does Lisi’s $E_8$ unification embed the Standard Model and gravity?
I'm reading the arXiv:0711.0770 paper An Exceptionally Simple Theory of Everything by A. Garrett Lisi. In the abstract, Lisi proposes to unify the Standard Model gauge fields and gravity using a ...
0
votes
0
answers
31
views
Why is the fermi energy level in between the valence and conduction band and not on top of the valence band? [duplicate]
Why does the fermi energy level exist between the valence and conduction band? What's the difference between the fermi level and the valence bond, should they not be the same since If at T=0K, all ...
2
votes
1
answer
181
views
What is the scientific community's take on causal fermion systems? [closed]
I recently came up to a podcast where Finster exposed his theory of "causal fermion systems" (CFS) and kind of intrigued me, here is the link. He seems pretty confident about his results so ...
- 753
0
votes
0
answers
13
views
Is there a graph of various attenuation processes across all energy regimes for any material?
I have been trying to find the absorption cross-section of extreme ultraviolet radiation for various atmospheric molecules, but most papers and graphs I've seen don't map that region, almost always ...
- 73
3
votes
0
answers
62
views
Negative geometries and positivity bounds?
Recently, Nima Arkani-Hamed and collaborators have discovered the relation between positive geometries that encode basic features of QFTs called positivity constraints like unitarity, causality, ...
- 3,344
0
votes
1
answer
76
views
Quarks' motion inside the neutron [duplicate]
Neutron's quark structure is udd.
In the neutron, how do the quarks move?
Do up quarks rotate around the down quark?
Do the down quarks rotate around the up quark?
Do they move like the two-body ...
-3
votes
0
answers
86
views
What is Higgs coupling to pions?
For a specific matrix element calculation (Dark matter annihilation into pions via a higgs portal), I need the coupling constant of higgs-pion. Since for fermions it's $M_f/v$, my intuition says that ...
- 5
-2
votes
0
answers
21
views
Does Relativistic Aberration Alter the Perceived Direction of Felt Forces Like Light? [duplicate]
I would provide context for this question, but last time I did, I apparently made it sound like I was presenting a new theory of physics or something, and the question got closed without an answer ...
- 1
3
votes
0
answers
49
views
Is the Choice of Minima in the Higgs Mechanism Arbitrary or Related To Producing a Massless Photon?
I'm trying to understand the choices made during derivations of the Higgs Mechanism. Particularly at the point where we have
$\phi^\dagger\phi = \frac{1}{2}\left(\phi^2_1+\phi^2_2+\phi^2_3+\phi^2_4\...
- 81