# Questions tagged [cpt-violation]

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### Are Hamiltonians CPT invariant?

I'm confused by the CPT theorem. It states (more or less) that a Lorentz invariant quantum field theory needs to be CPT invariant. But what does it actually mean for a QFT to be CPT invariant? It ...
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### Is $CPT$ Symmetry already broken?

i came up this paper recently: https://doi.org/10.1140/epjc/s10052-020-08549-9 it describes the "CPT violation with decoherence effects" by Neutrinos. This means CPT Symmetry is broken? And ...
102 views

### Why does spin break time reversal symmetry but electric dipole moment does not break time reversal symmetry?

I wasn't able to get a proper reason behind this and the only thing I could find were classical analogies for spin which (when I asked my prof) were not to be relied upon.
271 views

### What is relation between CPT invariance & Lorentz invariance, and why mass of particle/antiparticle is different in CPT violation?

(1) I read that CPT theorem can be proved with Lorentz invariance. Also, CPT violation implies Lorentz violation. Is CPT invariance equivalent with Lorentz invariance, or just one-side direction holds?...
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1 vote
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### Does symmetry violation make a approximate conservation law?

I know that Noether's theorem relates conservation laws with symmetries, and I read that to find CPT violation, Lorentz invariance symmetry needs to be broken. This implies that if a symmetry is ...
97 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 ...
303 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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554 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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### Could an antimatter-dominated end of universe fix CPT?

My question is about the apparent CPT violation of the observed universe, due to the imbalance of matter and antimatter, but first I have a motivating observation: General relativity respects time ...
• 3,713
190 views

### Electric dipole moment(EDM) underlying physics [duplicate]

I read in a physics today paper, The electron can have nonvanishing EDM only if nature violates symmetry under time reversal (T) and under the combined operations of charge conjugation (C), which ...
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### CPT and event horizon

Is the example of neutrino entering the event horizon of BH quoted from this article a valid possible example of CPT violation due to the presence of event horizon in BH ? Please, note that there is a ...
597 views

### How is this not a violation of CPT symmetry?

Imagine an electron and a positron, initially held stationary some distance apart at time $t=0$. There is an attractive force between them, so they will approach one another. I am told that all the ...
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### Can the time direction of wave function collapse be reversed? [duplicate]

The laws of physics are invariant under CPT transformations reversing time, inverting space and flipping charges. Almost so. The collapse of the wave function is the odd man out. Can the time ...
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### Does kaon decay etc prove "CP violation" or just "CP or CPT violation"

Shlomo Sternberg (math professor at Harvard) wrote a book called "Group theory and physics". On p156 (link) there's a strange offhand comment: "Experiments done in 1964 by Fitch and Cronin seem to ...
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456 views

### Self-antiparticles and broken symmetries

certain particles (i.e: certain bosons like the photon) do not have an anti-particle, or rather, they are they own anti-particles. Let's assume that such symmetry is only approximate and these ...
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A recent experimental paper measures a difference between the top quark and anti-top quark masses: Fermilab-Pub-11-062-E, CDF Collaboration, Measurement of the mass difference between $t$ and \$\bar{t}...