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seen Feb 24 at 15:58

Feb
13
comment Feynman Diagrams in 2 component notation
Try this paper
Feb
13
comment Quantum corrections to massless fermionic field
I am afraid I am not able to give you a solid answer. In this particular case (electron = massive QED fermion) you have to calculate the electron self-energy Feynman diagram correction (electron line with a virtual photon), this gives a correction with a $\not{p}$ term and a $m$ term. I have the feeling that it is the same logic for all massive fermions, but I am not able to give you a solid proof (maybe a new PSE question will be interesting).
Feb
7
comment Warped AdS${}_3$ and symmetry breaking
Well, maybe you are right, In fact, in page $6$, they speak of a "non-compact" $U(1)$, so it is not necessary an angle... so I deleted my previous comment.
Feb
7
comment Warped AdS${}_3$ and symmetry breaking
If this kind of approach (or an equivalent one) is correct, the difficult work would be to find the function $F_\lambda$, corresponding to some $\lambda$ model in the warped $\tau, \omega, \sigma$ metrics
Feb
7
comment Warped AdS${}_3$ and symmetry breaking
Maybe a possibility is to start with the original coordinates (see your previous question). The equation $(x^2+y^2)−(u^2+v^2)=−l^2$ exhibit the whole $SO(2,2)$ symmetry. Now, if we take for instance $(x^2+y^2)−(u^2+ (F_\lambda(x^2+y^2-u^2))^2 v^2)=−l^2$, ($F_\lambda$ is a function) ,we see that we have a $SO(2,1)\approx SL(2,R)$ symmetry, which is the invariance by $x^2+y^2-u^2 = Constant$, and we have a residual $SO(2) \approx U(1)$ symmetry, which is $u^2+ (F_\lambda(x^2+y^2-u^2))^2 v^2 = Constant$.
Feb
6
comment Warped AdS${}_3$ and symmetry breaking
In the appendix $A$ of your reference, you have an explicit expression for the $SL(2,\mathbb R)_R$ and $SL(2,\mathbb R)_L$ killing vectors. So you can verify than $2$ of them are no more Killing vectors for the warped metrics.
Feb
6
comment Why do quasicrystals have well-defined Fourier transforms?
Probably off-topic for your particular question, but this Wiki paragraph is interesting . I find also this recent presentation, and this curious article.
Feb
6
comment Parity transformation for spinors (pinors) in odd spacetime dimensions
Note that "spinors" correspond to the even part of the Clifford algebra, or, equivalently, to the algebra generated by the commutators $[\gamma_\mu, \gamma_\nu]$ (and the identity). So we work with $Spin (p,q)$ and $SO(p,q)$ rather than $Pin (p,q)$ and $O(p,q)$. For instance, $Spin(p,q) = Spin(q,p)$, but this isomorphism is not necessary true for $Pin$
Feb
6
answered A question about relativistic spin operator
Feb
6
answered Why the lowest order of matrices in Dirac equation are 4x4 matrices?
Feb
6
comment Hawking evaporation is due to NEGATIVE mass?
@JerrySchirmer : I find this explanation by prof Steve Carlip, very pleasant. There is no negative energy for the incoming particle, but a negative momentum, because the nature of the Schwarszchlid time and radial coordinates is changing at the horizon.
Feb
6
comment Non-locality and topology
The word "non-local correlations" should be avoided. Locality has to do with information or energy signal "sent" at some space-time point and "received" at an other space-time point, and this cannot be done instantaneously. Correlations, on the other way, are what they are. In any probabilistic system (classical or quantum), it is always possible that 2 subsystems of a systems locally get correlations,then, after, it is possible that these 2 subsystems may evolve into spatially distant locations, anyway, the correlations remain the same, because they concern internal state of the subsystems.
Feb
6
comment Understanding the algebra associated with an implicit potential
I don't understand from where comes your algebra $so(3)$.
Feb
6
comment What is the geometrical interpretation of Ricci tensor?
@cesaruliana : OK, thanks for the reference.
Feb
5
revised Changing vector basis in AdS_3
Correction
Feb
5
comment Understanding the algebra associated with an implicit potential
If I understand correctly, the chapter $V$ of your reference does prove that, starting from the expression of the casimir $C_2$, and ending with the Natanzon potential.
Feb
5
answered Changing vector basis in AdS_3
Feb
5
comment What is the geometrical interpretation of Ricci tensor?
@cesaruliana : The link with the Petrov Classification is a good remark. I effectively saw some papers insisting on the relations between gravitational waves and Petrov classification.
Feb
1
comment Light cones and reference frames
For a time-like interval, with any change of frame, you are stuck in the upper (or the lower) sheet of the 2-sheet hyperboloid. But you cannot go from the upper sheet to the lower sheet.
Feb
1
comment Questions on entanglement entropy
Note that the relation $S = [\beta \frac{\partial}{\partial \beta} - 1 ](\beta F)$, is a standard relation, for a canonical ensemble. It comes easily from the definition of $F= - \frac{1}{\beta} \ln Z$, the definition of the partition function $Z= \sum\limits_i e^{-\beta E_i}$, the definition of the entropy $S=-\sum\limits_i p_i \ln p_i$, with $p_i = \frac{1}{Z} e^{-\beta E_i}$.