All Questions
Tagged with quantum-field-theory renormalization
1,352
questions
-2
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QED with massless fermions
Consider QED such that physical mass of fermions vanishes. Is it true that their bare mass also vanishes?
- 2,226
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1
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100
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$\phi^4$ quantum fields theory with vanishing physical mass
Let us consider the $\phi^4$ theory, where $\phi$ is a real scalar field, such that the physical mass vanishes.
Is it true that the bare mass also vanishes?
- 2,226
2
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1
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146
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QFT with massless particles
EDIT: Often in textbooks one discusses QFT with massless particles, e.g. massless fermions or scalar particles. What mass vanishes: bare or physical? or both?
- 2,226
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Loop Effect of $\phi$ Propagator in $t$-channel of scalar $\phi^3$ theory [closed]
In Schwartz's QFT chapter 16, he calculates the loop effect (vaccum polarization) of $\phi$ propagator in $\phi^3$ theory, with the choice of Pauli-Villars regulator, the scattering amplitude would be
...
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Understanding Feynman Diagrams in Loop Corrections to the propagator $\phi ^3 $ theory [closed]
I found other posts talking about the same chapter in the same book, but none of them were exactly about what I am asking here.
In Srednicki's chapter 14 (Loop corrections to the propagator), we are ...
2
votes
1
answer
113
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What does it mean to "resum" the large logarithms?
I am struggling to understand the concept of resummation of large logarithms in QFT; from what I learnt so far the problem relies on the fact that if a full theory defined in the UV contains much ...
- 475
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1
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83
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Asymptotic Freedom QCD
I'm trying to understand the derivation of asymptotic freedom with the renormalisation group equations. I'm reading Taizo Muta's book on QCD. What I don't understand is how he obtains the last ...
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4
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0
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107
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Canonical commutation relation in QFT
The canonical commutation relation in QFT with say one (non-free) scalar real field $\phi$ is
$$[\phi(\vec x,t),\dot \phi(\vec y,t)]=i\hbar\delta^{(3)}(\vec x-\vec y).$$
Is this equation satisfied by ...
- 2,226
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52
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Conformal invariance and mass terms in QFT
We know that a physically sensible QFT must be renormalizable. If I understand correctly, when this happens, the theory has "asymptotic freedom" and is conformally invariant past some high ...
- 407
16
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3
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3k
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Why is finding a mathematical basis for the fine-structure constant meaningful?
I was reading QED by Richard Feynman and at the end he mentions that:
There is a most profound and beautiful question associated with the observed coupling constant, $e$ – the amplitude for a real ...
- 169
3
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74
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Charge Renormalization in Abelian Gauge Theory under General Gauge Fixing Conditions
In scalar QED or fermionic QED, the relationship between bare quantities (subscript "B") and renormalized quantities is given by
$$
\begin{aligned}
A^\mu_B &= \sqrt{Z_A} A^\mu\,, \quad \...
- 51
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One-Loop beta function for gauge couplings
I am currently doing my homework on Standard Model one-loop correction. When I am reading Quantum Field Theory by Mark Srednicki and Journeys Beyond the Standard Model by Pierre Ramond, I notice some ...
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32
votes
8
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5k
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Explain to a non-physicist what goes wrong when trying to quantize gravity
I am not a physicist, but I'm trying to get a little bit of an understanding of why it is hard to extend the standard model with quantum gravity (i.e. why it's hard to combine QM and GR), cf. e.g. A ...
- 1,772
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1
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70
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Loops and UV divergences
I read when asked whether a force could only exist at a certain phase transition or high energy:
"I am not aware of a coupling that only exists at high energies or in a phase transition -- in ...
- 425
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$Z_1=Z_2$ and its relation to vertex renormalization in QED
I have been working on the full renormalization of scalar QED with self-interactions, following the steps of Schwartz’s treatment on spinor QED (Chap 19). I have 3 main questions regarding this:
Need ...
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