Questions tagged [cpt-symmetry]

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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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Time-reversal transformation acts on the Dirac lagrangian with nonabelian gauge field

Time-reversal transformation acts on the Dirac lagrangian with (non)abelian gauge field Since earlier in Time-reversal transformation acts on the Weyl lagrangian with nonabelian gauge field, we ...
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Time-reversal transformation acts on the Weyl lagrangian with nonabelian gauge field

I would like to show time-reversal transformation acts on the Weyl lagrangian in the familiar 4 dimensional space-time. My notation follows the same as Peskin QFT book, such as that of chapter 3. I ...
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Regarding the action of Time reversal on Dirac spinors

I'm inquring about the difference between notions of time reversal found in Streater & Wightman's "PCT, Spin and Statistics, and All That", and this accepted answer from Chiral Anomaly. ...
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Does the CPT theorem imply $CP=T$?

Does the CPT theorem imply $CP=T$? That is, does it imply that the action of Charge Conjugation and Parity inversion on some representation of the Lorentz group, is the same as doing a time reversal? ...
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Help me understand the CPT signatures of different physical quantities

I am an engineer and not a trained physicist, but still I am fascinated by symmetries and I want to understand them. Specifically, in a paper ¹ I found the below table which covers a large number of ...
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Why is CPT symmetry necessary to prove the spin-statistics theorem?

I was reading the Wikipedia article on the spin-statistics theorem. It has a section going through a "suggestive bogus argument", where they rotate products of fields. To show why it doesn't ...
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Sign discrepancy in CPT theorem

I'm reading Fundamentals of Neutrino Physics and Astrophysics by Carlo Giunti and Chung W. Kim (2007). In chapter 2 section 11.5, they talk about the CPT theorem and how each fermion bilinear ...
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$C$, $P$, $T$ symmetry of $O(3)$ non-linear sigma model

Consider the $O(3)$ nonlinear sigma model with topological theta term in 1+1 D: $$\mathcal{L}=|d\textbf{n}|^{2}+\frac{i\theta}{8\pi}\textbf{n}\cdot(d\textbf{n}\times d\textbf{n}).$$ The time reversal ...
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Is CPT a unitary symmetry or an antiunitary symmetry?

Is CPT a unitary symmetry or an antiunitary symmetry, such as the free Dirac theory of fermion $\psi$ in Chapter 3 of Peskin's QFT book? Since T is antiunitary symmetry, P is unitary symmetry, C is ...
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Complex conjugation in time-reversal $T$ symmetry v.s. in charge conjugation $C$ symmetry

How is the complex conjugation $K$ of time-reversal symmetry $T$ differed by the complex conjugation of charge conjugation $C$? How are they differed from each other? For instance, take the Dirac ...
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Zee's book on QFT on the spin-1/2 state has $T^2=-1$, why not $T^2=+1$

In Zee's book on QFT, p.103, he showed that the spin-1/2 state has $T^2=-1$ by finding that the $T = UK$ has a matrix $U\propto \sigma_2$ and a complex conjugation $K$. However, how do we know that we ...
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How do the boundary conditions on lattice fields ensure that the particle has the correct symmetries in the perspective of CPT theorem?

Imagine for simplicity that we have scalar fields. Why don't we just impose on it the symmetries dictated by CPT theorem instead of using the boundary conditions as given in literature? A detailed ...
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Why might violation of Lorentz symmetry imply violation of CPT symmetry?

Several articles that I am currently reading have suggested that violating Lorentz symmetry (equivalence of physical law in all inertial reference frames) implies the violation of CPT (charge-parity-...
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How does Lorentz invariance link in with CPT symmetry?

I'm reading several articles on the relation between Lorentz symmetry (invariance under Lorentz transformations) and CPT symmetry; however, they all invoke high-level mathematics which I cannot ...
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Polchinski's notes on CPT and Spin-Statistics

On Polchinski's website for Physics 221B, QFT, Winter 2015, there is a link that is supposed to contain notes on CPT and Spin-Statistics, but the link is dead. Does anybody have these notes, and if so ...
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CPT invariance in Dirac Bilinears

I am currently working on exercise 3.7c of Peskin and Schroeder's An Introduction to Quantum Field Theory. The problem statement is: Show that any Hermition, Lorentz scalar local operator built from $...
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How does CPT symmetry hold while Charge, Parity and Time can all be violated?

To get it straight, Charge symmetry can be broken by U-236 atoms, Parity can be broken by K-one atoms and Time symmetry can be broken by quarks. So, how do they together hold true?
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Does time symmetry cause the matter/antimatter asymmetry?

It’s known that the fundamental laws of physics are time symmetric. In electromagnetism $t$ can be changed to $-t$ and time reversal is also valid in particle physics, as there is the 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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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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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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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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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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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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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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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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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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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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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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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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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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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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5 votes
2 answers
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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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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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2 votes
1 answer
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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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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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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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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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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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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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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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