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The theoretical symmetry of physical laws under the transformation of time reversal, that is t -> -t.
3
votes
Accepted
How to generalize the momentum reversal operator?
The "complex conjugation" operator is basis dependent and so ill defined.
A vector that has real components in one basis may be have complex components in another. For example the $x\leftrightarrow …
7
votes
Accepted
Is any Hamiltonian time reversal symmetric?
The algebra here is, as far as I can see correct, but there is a conceptual issue that has confused me in the past. In @Vokaylop's construction we find a $U_T$ that is constructed for this particula …
2
votes
Conjugate relations?
the operation $X\mapsto A^{-1}XA$ is usually called conjugation of $X$ by $A$ because this is the language used in group theory. I assume that by $\dagger$ the author means inverse, because antilinear …
2
votes
PT transformation of a spinor
I find that your $S(\Lambda_T)$ should be $\gamma^1\gamma^2\gamma^3$ as that flips the $\gamma^0$ three times, but flips the other three gammas twice.
But be careful the actual action of $T$ on spin …
2
votes
PT-Symmetry and the existence of a preferred reference frame
If P and T are good symmetries in any one specific reference frame then they are good symmetries in any frame in a Lorentz invariant theory.
2
votes
What are the implications that the Hamiltonian of a material lacks time reversal symmetry?
It usually just means that the material is magnetic, since magnetization ${\bf M}$ changes to $-{\bf M}$ under time reversal.
2
votes
What is the logic connection between these two statements?
1) Time reversal takes ${\bf k}\to -{\bf k}$. 2) Time reversal takes the Berry curvature ${\bf \Omega}\to -{\bf \Omega}$. Therefore $\Omega(-{\bf k})=-\Omega({\bf k})$. I think it really is this sim …
2
votes
Regarding the action of Time reversal on Dirac spinors
There are two definitions of time reversal, one of which changes particle to antiparticles. The second, the Wigner definition, does not and is the one usually used these days.
2
votes
Accepted
Hamiltonian invariant under time reversal symmetry
I think that you are confusing the unitary matrix $O$ that appears in the first quantized formula
$$
OH^*O^{-1} =H
$$
with the antilinear operator $T$ that acts as on the second quantised field operat …
0
votes
Time reversal operator and Dirac gamma matrices
It's best to avoid basis dependent formulae such as the one you use. The time reversal matrix is defined in all space-time signatures by
$$
T \gamma^\mu T^{-1}= {(\gamma^\mu)}^T
$$
where $(\gamma^\m …