quantum-field-theory

  1. Fermions, different species and (anti-)commutation rules

  2. Does quantum field theory need time?

  3. What is the calculation rule of the normal ordering operator?

  4. Why does unitarity require the Higgs to exist?

  5. Why does the non-linearity of the string action prohibit stretching due to strong excitations?

  6. Energies of this field Hamiltonian?
  7. Is there a simple way to understand why SUGRA is two-loop renormalisable?

  8. What's the physical interpretation of a time-ordered correlator of currents?

  9. Non-Fock representation of quantum field theory

  10. Why do we care about old-style, counterterm renormalizability?

  11. Renormalisation of NSLM in 2D

  12. Doubt regarding Thomas banks equation about perturbation
  13. How does mass of the exchange particles affect the range of a force?
  14. Massive vector boson propagators and renormalizability
  15. Can dimensional regularization be viewed as a soft version of a Wilsonian cutoff?

  16. Momentum and Higgs Fields

  17. How are second-class constraints handled in the path integral formulation?

  18. Cutoff-dependent "inverse propagator" for renormalization

  19. Are Feynman rules unique?

  20. What is the position-space form of the photon propagator in a general gauge?
  21. Why is the auxiliary field from Hubbard-Stratonovich transformation for Hubbard model the same as the mean-field ferromagnetic order parameter?

  22. Origin of heat kernel regularization
  23. What is the Grassmann parameter $\epsilon$ in the BRST transformation?

  24. How are coherent states in the real world made?

  25. Counting massive degrees of freedom after gauge fixing
  26. Reference Request: Invariant Feynman amplitudes with global symmetry on Lagrangian

  27. Why does Josephson's identity $d\nu=2-\alpha$ only hold for mean field theory in dimension $4$?

  28. Can we say the origin of spin is due to mixing of various components of field under Lorentz transformation?

  29. Relation between Wilsonian renormalization and Counterterm Renormalization

  30. Calculating $\mathrm{Tr}[\log \Delta_F]$
  31. Quantum Field Theory Interpretation of $\hat{\phi}|0\rangle$

  32. Spin magnetic moment direction of a particle

  33. Calculation of Feynman invariant amplitude with internal global symmetry indices: trace over\and isospin
  34. Is it true that matter and antimatter must have same mass?

  35. Perturbation theory around solvable but non-free hamiltonian
  36. Proof of cluster decomposition theorem

  37. Renormalization of mass of an electron inside the crystal

  38. What are thermal photons?

  39. Thermal field theory of isolated electroweak plasma
  40. Difference of vacuum states

  41. Clarification on contraction

  42. Interpretation of correlation functions that are higher than 2 point

  43. Hamiltonian with periodic potential in second quantization

  44. Schrodinger Wave Functional (quantum fields) - Solving Functional Gaussian Integrals
  45. Green's functions in the Keldysh-formalism and quantum stochastic calculus

  46. Flavor symmetry fixes the Higgs branch in any 4D ${\cal N}=2$ QFT
  47. Commutator of canonical fields in Quantum Field Theory

  48. if our universe was/behaved like a quantum computer, could it behave like a boltzmann brain?

  49. Is this interpretation of quantum fluctuation in eternal inflation in Wikipedia correct?

  50. Is the Rindler vacuum invariant under Poincare symmetries?
  51. Is it possible to ensure the diagonalization of the minimal coupling Hamiltonian?

  52. Adding energies vs. adding momenta

  53. Lorentz-invariant phase space for 2->2 scattering
  54. What is a contraction in QFT?
  55. Pi / Euler-Riemann / Golden Ratio in physics?
  56. How do you set the phase space area for the simulation of a quantum system?

  57. 'Quantized' increase in velocity? Or 'quantized' acceleration perhaps?

  58. gauge-invariant 6-quark order parameter
  59. One-particle states in curved spacetimes
  60. Noether charge for Lorentz Transformation in terms of creation / annihilation operators

  61. Energy density drops in all regions of space in Standard inflation, and in some regions of space in Chaotic/Eternal inflation

  62. Perturbative renormalization and Wilsonian approach

  63. Is there any Stack Exchange site for discussing Non-mainstream physics?
  64. Reparameterization and conformal transformation in SYK

  65. $\mu \rightarrow e\gamma$ in the $R_\xi$ gauge: trouble with momenta and Dirac matrices

  66. Would a high energy bottom quark 'decay' to a top quark?
  67. Self coupled scalar field theory of gravity
  68. S-matrix derived directly in terms of the interaction picture

  69. momentum and mode functions in QFT in curved spacetime
  70. What are periods of field strength?
  71. Full photon propagator in S-matrix calculation
  72. Why should the vacuum be unique?
  73. Question about convergence of Dyson Series. Why Dyson series is in general divergent?
  74. What conserved charge follows from the dual field strength tensor?
  75. When is this particle potential bounded?
  76. Symplectic reduction to moduli space in Chern-Simons theory
  77. Spontaneously broken linear sigma model in Peskin & Schroeder: where is the miracle?

  78. How long can a virtual particles exist in a vacuum state?

  79. What are mass eigenstates?

  80. Space tranlsation symmetry breaking
  81. Motivation for the definition of gaussian states
  82. A simple question about the scattering amplitude $\mathcal{M}$ in QFT
  83. Dirac field operator expansion in magnetic field

  84. Some clarification on Dirac and Weyl spinor terminology
  85. Inverse Square Law in $D$ dimensions (two cases)

  86. Diagram versus gradient expansion
  87. How does QFT in curved spacetime work when state is in momentum space?

  88. Computing Feynman Diagrams with Majorana and Dirac Fermions
  89. Gaussian integral in momentum space
  90. Difference, in relation to minus sign, between the processes: $gg \to q\bar q$ and $qg\to qg$

  91. What's the differences between pseudospin and spin?

  92. What is spin/charge relation in condensed matter physics?

  93. Lorentz boosting and Energy Scale

  94. Loop counting -- what if the graph is not planar?

  95. What is the mathematically simplest particle field?

  96. Classical field limit of the electron quantum field
  97. Under which conditions does an interaction-free quantum field represent physical reality well?

  98. Conformal invariance of Electromagnetic field action

  99. Why must fermion fields anticommute and bosons commute?

  100. LSZ theorem for photons