User ersbygre1

12 votes

1 answer

605 views

How do we know from representation theory that a massless spin-1 particle has only two polarizations?

asked Jun 4, 2020 at 0:37

11 votes

3 answers

666 views

Chirality of the Electromagnetic Field Tensor

group-theory group-representations chirality duality

asked Sep 20, 2018 at 5:26

9 votes

1 answer

1k views

What is dynamical symmetry breaking, exactly?

quantum-field-theory symmetry symmetry-breaking

asked Oct 3, 2018 at 7:57

9 votes

1 answer

198 views

About Itzykson and Zuber's proof of Goldstone's theorem

quantum-field-theory particle-physics hilbert-space symmetry-breaking goldstone-mode

asked Jun 17, 2021 at 5:45

8 votes

1 answer

377 views

Counting degrees of freedom in the Higgs mechanism for different gauges

gauge-theory higgs symmetry-breaking gauge-invariance degrees-of-freedom

asked Oct 17, 2018 at 5:01

7 votes

1 answer

1k views

How to calculate an axial anomaly in 1+1 dimensions?

symmetry symmetry-breaking quantum-anomalies

asked Dec 9, 2017 at 15:35

6 votes

1 answer

358 views

How to deal with two-loop integrals in dimensional regularization?

quantum-field-theory feynman-diagrams integration regularization dimensional-regularization

asked Oct 27, 2020 at 9:45

5 votes

1 answer

839 views

Covariant Derivative in QCD: How does it act on gluons?

differentiation quantum-chromodynamics yang-mills gluons

asked Sep 27, 2018 at 8:26

5 votes

1 answer

730 views

On-shell and off-shell transformations in Noether's theorem

lagrangian-formalism conservation-laws symmetry action noethers-theorem

asked Nov 2, 2018 at 7:28

4 votes

1 answer

199 views

What is pion condensation (or hadron condensation in general)?

nuclear-physics quantum-chromodynamics pions condensation

asked May 10, 2021 at 2:26

3 votes

1 answer

117 views

Which quarks can form vacuum condensates?

quantum-field-theory vacuum quantum-chromodynamics quarks condensation

asked May 18, 2021 at 0:20

3 votes

1 answer

156 views

Normalization of momentum eigenstates in QFT

quantum-field-theory hilbert-space quantum-states normalization

asked Jun 18, 2021 at 10:04

3 votes

1 answer

726 views

What does the $R$ stand for in $R_\xi$ gauge?

specific-reference gauge

asked Oct 12, 2018 at 12:04

3 votes

1 answer

195 views

Why do particle resonances lead to peaks in the cross section?

quantum-field-theory singularities greens-functions scattering-cross-section s-matrix-theory

asked Nov 11, 2017 at 12:45

3 votes

2 answers

748 views

How are parity and charge conjugation eigenvalues related to angular momentum?

quantum-mechanics angular-momentum quantum-spin parity charge-conjugation

asked Nov 16, 2017 at 7:50

3 votes

1 answer

102 views

Are there finite-dimensional unitary irreducible representations in Euclidean space?

group-theory representation-theory unitarity

asked Jul 2, 2020 at 6:22

3 votes

1 answer

152 views

Using entanglement to transfer information faster than light

quantum-mechanics quantum-entanglement faster-than-light

asked Oct 4, 2019 at 23:55

2 votes

0 answers

237 views

Calculating the pion decay constant in Chiral Perturbation Theory

quantum-field-theory quantum-chromodynamics effective-field-theory pions

asked Feb 2, 2020 at 5:12

2 votes

1 answer

375 views

Dirac sea interpretation VS the Feynman-Stueckelberg interpretation for antiparticles

dirac-equation antimatter spinors helicity

asked Apr 1, 2020 at 4:41

2 votes

1 answer

106 views

Why do we need two gluons for the decay $ϕ \to 2K$?

particle-physics conservation-laws standard-model quantum-chromodynamics charge-conjugation

asked May 16, 2020 at 10:50

2 votes

1 answer

499 views

How many counterterms does QED have?

quantum-electrodynamics renormalization feynman-diagrams propagator

asked Nov 10, 2018 at 3:15

2 votes

1 answer

177 views

Showing that the Wess-Zumino Lagrangian is invariant under a SUSY transformation

lagrangian-formalism field-theory conventions supersymmetry spinors

asked Aug 7, 2020 at 1:27

2 votes

1 answer

168 views

How to calculate a real (vector) superfield in Wess-Zumino gauge

field-theory gauge-theory supersymmetry gauge

asked Nov 23, 2017 at 4:33

2 votes

2 answers

282 views

How to interpret $\langle\pi|J|\pi\rangle$?

quantum-chromodynamics

asked Mar 18, 2018 at 9:50

2 votes

2 answers

82 views

Fabri-Picasso theorem: Why can we assume that the charge commutes with momentum?

symmetry symmetry-breaking noethers-theorem

asked Oct 19, 2018 at 2:57

2 votes

1 answer

107 views

Why are Delta baryons called "Delta isobars"?

terminology quantum-chromodynamics isospin-symmetry baryons

asked May 20, 2021 at 4:44

2 votes

2 answers

132 views

How does the propagation of a complex scalar field work?

quantum-mechanics quantum-field-theory field-theory conventions propagator

asked Aug 15, 2021 at 13:33

2 votes

1 answer

124 views

Connection between quaternions and electromagnetism

electromagnetism magnetic-fields electric-fields complex-numbers

asked Jan 17 at 13:31

2 votes

1 answer

46 views

Feasibility of the Aharonov-Bohm effect

electromagnetism magnetic-fields potential experimental-technique

asked Nov 23, 2020 at 2:57

1 vote

1 answer

86 views

Why does the Lorenz gauge $\partial_\mu A^\mu=0$ eliminate the spin-0 part of $A^\mu$?

lagrangian-formalism field-theory quantum-spin representation-theory degrees-of-freedom

asked Mar 3 at 14:31

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49 Questions

How do we know from representation theory that a massless spin-1 particle has only two polarizations?

Chirality of the Electromagnetic Field Tensor

What is dynamical symmetry breaking, exactly?

About Itzykson and Zuber's proof of Goldstone's theorem

Counting degrees of freedom in the Higgs mechanism for different gauges

How to calculate an axial anomaly in 1+1 dimensions?

How to deal with two-loop integrals in dimensional regularization?

Covariant Derivative in QCD: How does it act on gluons?

On-shell and off-shell transformations in Noether's theorem

What is pion condensation (or hadron condensation in general)?

Which quarks can form vacuum condensates?

Normalization of momentum eigenstates in QFT

What does the $R$ stand for in $R_\xi$ gauge?

Why do particle resonances lead to peaks in the cross section?

How are parity and charge conjugation eigenvalues related to angular momentum?

Are there finite-dimensional unitary irreducible representations in Euclidean space?

Using entanglement to transfer information faster than light

Calculating the pion decay constant in Chiral Perturbation Theory

Dirac sea interpretation VS the Feynman-Stueckelberg interpretation for antiparticles

Why do we need two gluons for the decay $ϕ \to 2K$?

How many counterterms does QED have?

Showing that the Wess-Zumino Lagrangian is invariant under a SUSY transformation

How to calculate a real (vector) superfield in Wess-Zumino gauge

How to interpret $\langle\pi|J|\pi\rangle$?

Fabri-Picasso theorem: Why can we assume that the charge commutes with momentum?

Why are Delta baryons called "Delta isobars"?

How does the propagation of a complex scalar field work?

Connection between quaternions and electromagnetism

Feasibility of the Aharonov-Bohm effect

Why does the Lorenz gauge $\partial_\mu A^\mu=0$ eliminate the spin-0 part of $A^\mu$?