All Questions
Tagged with quantum-field-theory particle-physics
1,059
questions
2
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0
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66
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Why don't virtual electrons get generated near protons to form atoms?
If forming an atom is a more stable state for both the electron and the proton, why don't virtual electrons get generated near protons so that they combine with them to form atoms, and then release ...
- 185
2
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1
answer
112
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What experimental data do we have to plug into the Standard Model for it to work?
In the formulation of the Standard Model, I've always been told that we need experimental data to fix some parameters. What are these parameters and how vital is it that we have the exact value? In a ...
- 298
-3
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1
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86
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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 ...
0
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2
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645
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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 ...
- 4,452
3
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2
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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 ...
- 31
1
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1
answer
100
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Particle number in lattice field theory
Is it even possible to calculate a particle number of some field in lattice field theory? After all, it's implemented in the formalism of imaginary time path integrals, here's no such concepts as ...
- 343
5
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0
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230
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Another "real vs virtual particle" one: calculate the full diagram or $\sigma \times \mathrm{BR}$?
I have recently been forced to think about something I always thought that I understood but that, in reality, I could not be more confused about.
Suppose I want to study the LHC prospects for ...
- 1,742
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161
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Important typo in Schwartz's QFT: Incorrect spinor solutions leading to wrong charge conjugation properties
Eq 11.18 in Schwartz's book reads:
$$u_{\uparrow}=\sqrt{m}\begin{pmatrix}1\\0\\1\\0\end{pmatrix}
u_{\downarrow}=\sqrt{m}\begin{pmatrix}0\\1\\0\\1\end{pmatrix}
v_{\uparrow}=\sqrt{m}\begin{pmatrix}-1\\0\...
- 619
0
votes
1
answer
121
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A problematic equation for Dirac field:$[\psi,\hat{J_z}]=J_z\psi+i(x{\partial \psi\over\partial y}-y{\partial\psi\over\partial x})$ How is this true?
The Dirac field is quantized as:
$$\psi(x^\mu)=\int{d^3 p\over(2\pi)^3\sqrt{2\omega_p}}[a_s(p)u_s(p)e^{-ipx}+b_s^{\dagger}(p)v_s(p)e^{ipx}]$$
In the title:$$[\psi,\hat{J_z}]=J_z\psi+i(x{\partial \psi\...
- 619
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2
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112
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Are particles and waves limits of quantum fields?
In quantum field theory we often hear that particles sometimes behave like waves and sometimes behave like particles.
In quantum field theory we say particles are fundamentally fields.
Is it correct ...
- 525
1
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1
answer
128
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Why are the field operator eigenstates a complete basis of the Fock space? How to properly define the measure $\mathcal{D}\Phi(x)$?
This is a question which has plagued me for a long time.
In the path Integral, we insert$\int\mathcal{D}\Phi(x)\vert\Phi\rangle\langle\Phi\vert=\mathcal{I}$ and $\int\mathcal{D}\Pi(x)\vert\Pi\rangle\...
- 619
2
votes
1
answer
132
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Which spinor should be used for an outgoing proton if we treated it like a point particle? $\bar{u}(p)$ (as for electron) or $v(p)$ (as for positron)
Consider the Rutherford scattering $e^-p^+ \rightarrow e^-p^+$
If a proton is a treated as a heavier positron:
$i\mathcal{M}=(-ie)\bar{u}(p_3)\gamma^{\mu}u(p_1)i\Pi_{\mu\nu}(-ie)\bar{v}(p_2)\gamma^{\...
- 619
4
votes
1
answer
174
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Is the notion of particles dependent upon the Hamiltonian being quadratic?
I am studying interacting QFT in the context of quantum fields in curved backgrounds, and I am getting some confussion about the concept of particles. To study some gravitational phenomena involving ...
- 503
2
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1
answer
1k
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Why are particles still a thing? [closed]
Couldn't we just assume that waves have mass and momentum and can become localized? Dirac Deltas can be given a rigorous mathematical foundation but physicist do not use the Gelfand triple. Why not ...
- 83
1
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60
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Decay rate with specific helicity in rest frame and lab frame
Consider a two-body decay, such as the pion decay: $\pi^+\to \mu^+ + \nu_\mu^{}$. In the Standard Model, as there only exits left-handed massless neutrinos, the helicities of final particles are known....
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