Questions tagged [cpt-symmetry]

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Negative energy quanta vs antimatter approach

Consider 2 physical scenarios: $t_{-1}$ $t_0$ $t_1$ Sc.1 electron and positron approached electron and positron annihilated photons emitted Sc.2 electron is free electron emits some photons ...
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36 views

Electromagnetism and CPT simmetry

I'm having some trouble understanding the CPT theorem and in particular the time reversal part. Let's consider for example an electron and a positron on the x axis, with the electron on the left and ...
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147 views

Critique on various ways to think about time reversal transformation on Schrodinger equation?

Please define how time-reversal symmetry act on Schrodinger equation $i \frac{\partial}{\partial t} |\Psi{}(t) \rangle = H(t) |\Psi{}(t) \rangle.$ (for general form: which can be relativistic such as ...
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30 views

Charge Conjugation to Analyze CPT Invariance

Source: http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/cpt.html#:~:text=Charge%20conjugation(C)%3A%20reversing,like%20momentum%20and%20angular%20momentum. In the image below, reaction (1) shows ...
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41 views

Can one-electron world theory be revived if the Sakharov's conditions are completely met?

Regarding that people object about the matter antimatter balance in the one-electron world theory to discard it, can it be once more revived if the Sakharov's conditions are met so that the matter ...
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1answer
76 views

Examples of the vacuum $| 0 \rangle$ break C, P, T symmetry?

Can the vacuum $| 0 \rangle$ of some QFT break C, P, T symmetry? It could be that the QFT break C, P, T symmetry explicitly. Are there good examples? p.s. The weak interaction breaks P explicitly ...
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1answer
63 views

Define $C,P,T$ symmetry transformation in even dimensional $d$ spacetime on a relativistic Weyl fermion theory

According to https://physics.stackexchange.com/a/488388/42982 we can define $C,P,T$ discrete symmetry transformation in even dimensional spacetime. How could we write $C,P,T$ symmetry transformation ...
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56 views

Does the time reversal flip the differential measure $dt$?

Does the time reversal flip the differential measure $dt$ or integral measure $dt$? Does the time reversal flip the differential measure $dt$ or $\Delta t$? Suppose we look at the derivative on a ...
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Does the presence of magnetic monopole break the time reversal, or does its magnetic charge flip (more naturally)?

It is often said that the presence of magnetic field breaks the time reversal symmetry (see Sakurai quantum mechanics book p.285), because the Lorentz force law shows $$ \vec F = q(\vec E + \vec v \...
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Difference between non-Hermitian and PT-symmetric systems [closed]

Can anyone explain me the difference between non-Hermitian and PT-symmetric systems (in terms of the Hamiltonian)? Are they two mutually exclusive things?
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What is the difference between “time symmetry violation” and “time reversal”?

I am getting confused by the various terms used in the literature. There is "time (reversal) symmetry" that is violated in experiments and there is "time reversal". For context, I ...
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Is there one or more field of physics where $T$-symmetry is broken? [duplicate]

I've learned about the 'CPT Symmetry' and CP violation which indicates that if CP violation is true, which is considered for the existence of a universe made of matter rather than antimatter. But this ...
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57 views

Why reflection is generator of Minkowski space, if we know that only CPT symmetry is true?

In particular, we know that $P$ symmetry (parity transformation, which is basically a reflection), is not the symmetry of the universe, a whole combination of $C$, $P$, and $T$ is. Because of this, it'...
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How can we detect antihydrogen?

From a mathematical standpoint (CPT symmetry) it is most probable that antihydrogen has the same spectra (absorption and emission) as hydrogen. The CERN confirmed this hypothesis to a high accuracy ...
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CPT theorem and the weak interaction

I am trying the understand how the weak interaction obeys CPT symmetry. My understanding is that, under a CPT transformation, the Lagrangian for the Standard Model should be invariant, and thus the ...
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22 views

Which constrained trajectories of an ensemble of charges maintain time reversibility without additional fields?

Maxwell's equations are time reversible, and the fields can be written in terms of the sources via the Lienard-wiechert fields. However, the fields written in terms of the sources alone are not ...
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31 views

How do the time reversed retarded solutions to Maxwell's equations maintain T-symmetry?

Maxwell's equations are T-symmetrical in that they remain invariant to a change in the sign of $dt$ if the sign of $B$ and $J$ are also reversed. Hence the corresponding time reversed solution is ...
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93 views

C, P and T transformations of $\phi$ that preserves symmetry

I have a series of exercises regarding C, P and T symmetry but I am not really sure how to start with the problems. If anyone could help me with one of the problems, or show me a few example problems ...
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What is CPT, really?

The naive statement for the "CPT theorem" one usually finds in the literature is "relativistic theories should be CPT invariant". It is clear that this statement is not true as written, e.g. ...
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63 views

Decomposing the $\mathcal{N} = 4$ massless graviton supermultiplet

I'm trying to solve the following exercise: Construct the physical states of the $\mathcal{N} = 4$ massless graviton supermultiplet, starting from a Clifford vacuum of helicity $λ_0 = 0$. Decompose ...
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117 views

Electric dipole moment (EDM) and CP violation

It's well known that a non-zero value for the electric dipole moment (EDM) would imply CP violation. If we consider the interaction Hamiltonian of an EDM $d$ with an electric field $\vec{E}$, $$ H = -...
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69 views

QED $PC$ conservation

I'm trying to prove that the QED Lagrangian $$\mathscr{L}=\bar{\psi}(i\!\!\not{\!\partial}-m)\psi - \frac{1}{4}F^{\mu\nu}F_{\mu\nu} - J^\mu A_\mu$$ Is invariant under P and C. The two fields transform ...
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173 views

Why isn't EM radiation from an accelerated charge time reversible?

Let a charge $q$ enter a constant magnetic field $B$ at 90 degrees, hence radiating EM energy-momentum and spiraling inwards to some point as it slows down. Time reversing this, including the current ...
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169 views

Why aren't black holes antimatter fountains?

As I understand it, nothing can escape a black hole because the only worldlines leading 'out' from the event horizon point backwards in time. As I understand it, antimatter is time-reversed ordinary ...
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49 views

Does it mean time reverses if all particles were antiparticles and vice versa?

First of all, I'm not major in physics and the question might seems stupid, as I'm layman studying for my self-interest and I really don't know much about it. I only think it might open some ...
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157 views

Does charge conjugation symmetry sit in the Lorentz group?

We know the Lorentz group is $O(3,1)$ in 4 dimensional spacetime. We know that there are 4 disconnected components in Lorentz group $O(3,1)$, and https://math.stackexchange.com/q/2204349/ $$\pi_0(\...
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Are all processes time/CPT-reversible, e.g. measurement, stimulated emission, state preparation, Big Bang?

"The CPT theorem says that CPT symmetry holds for all physical phenomena, or more precisely, that any Lorentz invariant local quantum field theory with a Hermitian Hamiltonian must have CPT symmetry." ...
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Does the CPT theorem hold for all spacetime dimensions?

I can't find any reference which mentions the dependence of the theorem on spacetime dimension, but it would be very interesting to know what if any it has!
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257 views

CPT transformation for bilinears

In the page 5 of the document 'CPT Symmetry and Its Violation' by Ralf Lehnert (https://core.ac.uk/download/pdf/80103866.pdf), appears a discussion about how the spin-statistics theorem applies to the ...
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55 views

Arrow of time and CPT symmetry

It's been a few years since my physics degree. But I've been wondering: if you look at pictures of collisions at CERN, isn't it obvious which way time flows - simply on a probability basis? The ...
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65 views

Mathematical representation of Symmetry Transformation

Consider a general Hamiltonian that is made up of three terms $\mathcal{H}$ = term I + term II + term III . Suppose the combination of charge conjugation and parity (CP) is a symmetry of this ...
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1answer
493 views

Why is the Higgs $CP$ even?

Why was it always assumed that the Higgs boson is a CP even particle? I understand that experimentally, it just is so but I am under the impression that before its discovery people took it to be CP ...
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Antiparticles, CPT and leptogenesis

When people are being careful they'll tell you that antiparticles are the CPT conjugates of particles. You can't say that they are C conjugates or CP because these, while they do reverse the charge, ...
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512 views

C and T Symmetry of Free Dirac Lagrangian

I want to show the $C$ and $T$ symmetry of the free Dirac Lagrangian $$\mathcal{L}=\overline{\psi}\left(i\gamma^\mu\partial_\mu-m\right)\psi.$$ Following the notation of Peskin, Schroeder, we have ...
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176 views

Why is it important that the combination of charge, parity & time reversal symmetry not violated?

If looking for more particles or decays that violate CP symmetry can explain why there is so few antimatter in the known universe, I guess finding things that violate CPT symmetry might helps clear up ...
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162 views

Is time reversal symmetry true on the microscopic level?

I often hear that on the microscopic level, time-reversal symmetry is true for all physical processes. However, I can easily come up with counterexamples that seem to disprove this: Two particles of ...
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300 views

Does the weak force obey the CPT symmetry? How?

I have read that the weak force does not obey the charge symmetry, the parity symmetry, and the time reversal symmetry. Then how does it obey the CPT symmetry?
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695 views

What are the assumptions that $C$, $P$, and $T$ must satisfy?

I am not asking for a proof of the $CPT$ theorem. I am asking how the $CPT$ theorem can even be defined. As matrices in $O(1,3)$, $T$ and $P$ are just $$ T = \begin{pmatrix} -1 & 0 & 0 & ...
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How is a half-odd integer spin field defined in the Wightman axioms?

Can anyone give me a proper definition of 'half-odd integer spin fields' in terms of the Wightman axioms? I'm trying to prove the anti-unitarity of the PCT operator in 'PCT, Spin and Statistics, and ...
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161 views

What operator gives the mass of a particle?

Talking about why a particle and its antiparticle have the same mass, my professor said the Hamiltonian commutes with TCP, so mass is conserved. I don't understand that.
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107 views

Clarifying PT symmetry

I understand that if a Hamiltonian remains invariant under the following transformations then it is PT invariant, \begin{eqnarray} \mathrm{Parity \; reversal:} \; \; \hat{p} \to -\hat{p} \; \; \...
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2answers
240 views

Does reversing time give parity reversed antimatter or just antimatter?

Feynman's idea states that matter going backwards in time seems like antimatter. But, since nature is $CPT$ symmetric, reversing time ($T$) is equivalent to $CP$ operation. So, reversing time gives ...
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787 views

What is the definition of the charge conjugation?

I seem to have troubles finding definitions of the charge conjugation operator that are independant of the theory considered. Weinberg defined it as the operator mapping particle types to ...
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1answer
240 views

Clarification on CPT symmetry

CPT symmetry, as I understand it, holds that if all charge, parity, and time were reversed (a mirror-image antimatter time-reversed universe), that universe would behave identically to our current ...
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351 views

CPT symmetry as it applies to matter/antimatter

I've heard/read a couple different definitions for antimatter: it is charge-reversed matter (typical definition, for the lay person at least), or it's time-reversed matter (as described in QED). ...
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97 views

chiral symmetry condensate and 2SC, CFL breaking C, P and T symmetry?

Because we know that chiral symmetry condensate causes the chiral symmetry breaking, and it produces Goldstone modes of pseudo-scalars, so I believe that chiral symmetry breaking also breaks the T ...
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69 views

Is N=6 SUSY gravitino multiplet self-CPT?

I would like to understand why the $N=6$ gravitino (massless) multiplet $$\left(-\frac32,(-1)^{6},(-\frac12)^{15}, 0^{20}, (+\frac12)^{15}, +1^6, +\frac32 \right)$$ is not CPT self-conjuguate?. It ...
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93 views

How to understand $T^2=(-1)^{N_f}$ in terms of operator matrices on Hilbert space

For a time reversal symmetry operator $\hat{T}$, we have $$\hat{T}^2=(-1)^{N_f}$$ for a fermionic (electronic) system. How do we understand $\hat{T}^2=(-1)^{N_f}$ in terms of operator matrices on the ...
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Is it possible to have renormalisable C-, P-, or T-violating terms in QED?

In a recent paper (1710.01791), Witten claims that there are no renormalisable $\mathrm C,\mathrm P,\mathrm T$-violating terms that can be included in the QED Lagrangian: What does this picture say ...
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62 views

Instanton effects on condensates: (pseudo)scalars, (pseudo)vectors, tensor

I have heard that the instanton effect in quark matter causes the di-quark condensate to be Lorentz scalar. As opposed to the Lorentz scalar, there are possibilities that the condensates are Lorentz ...