Questions tagged [cpt-symmetry]

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I want to know about origin of non-Hermitian quantum field theory model having two complex scalar fields $\phi_1$ and $\phi_2$

In the paper Symmetries and conservation laws in non-Hermitian field theories by Jean Alexandre, Peter Millington, and Dries Seynaeve, Phys. Rev. D 96, 065027 the authors use this Lagrangian: $$ L = ...
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Thermodynamics of T-symmetry violation

Physics is mostly time reversible. But certain nuclear interactions violate this T symmetry. With T-symmetry a system at maximum entropy has no "arrow of time". Thus a video of the system ...
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Magnetic Monopoles and Its Antimatter and Mirror Particle Counterparts [closed]

I'm trying to understand how magnetic monopoles and how its potential mirror and antiparticle counterparts would behave. So according to the modified lorentz force law $$\vec{F}=q_e\left(\vec{E}+\frac{...
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Charge conjugation is a symmetry for the quantized free Dirac action?

I am self-studying QFT on "A modern introduction to quantum filed theory" by Maggiore, and on page 95 he states: "For the free Dirac action, one immediately sees that C,P and T are ...
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Confused about square of time-reversal operator $T$

I am reading An Introduction to Quantum Field Theory by Peskin & Schroeder, and I am confused about what is the square $T^2$ of time reversal operator $T$. My guess is that for $P^2$, $C^2$ and $T^...
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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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Non-Hermitian PT-symmetric Interacting Hamiltonian with Real Spectra

The following hamiltonian is $\mathcal{PT}$-symmetric $$\mathcal{H} = -J \sum_{j = 1}^{2N} [ 1 + (-1)^j \delta ] [ c^{\dagger}_{j} c_{j+1} + h.c. ] + \imath \gamma \sum_{j = 1}^{2N} (-1)^j c^{\dagger}...
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Are there theorems from electromagnetism that are a consequence of $C$, $P$ or $T$ invariance?

It's well known that classical electrodynamics is $C$, $P$ and $T$ invariant. For example, see this question Maxwell's equations and $C$, $P$, $T$ Symmetry. Are there theorems within CED that are a ...
Physiks lover's user avatar
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Is really hermiticity necessary to be a physical observable? What about larger class of operators like PT invariant operators or pseudo hermitian one?

It's really necessary for an observable represented by an operator acting in a Hilbert space to be hermitian? It's known that not only hermitian operators have real eigenvalues and that also normal ...
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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 ...
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Can you tell wavefunction's chirality by looking at it?

I recently learned, that: Helicity is a combination of particle's "rotation" (Spin) and direction of it's motion. The motion is relativity-dependant, and so is helicity. Chirality ...
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CPT invariance and Soft Theorems

I am reading the paper IR Dynamics and Entanglement Entropy, written by Toumbas and Tomaras and I have a question on using the CPT invariance of the QED $S$-matrix elements in order to derive the ...
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Enlarging the action of $C$, $P$ and $T$

I am now studying QFT using Schwartz's book, and I am going through the part discussing about how the charge conjugation, parity, and time-reversal operator acting on various object should look like. ...
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Time Reversal symmetry, Quaternions, and spin-1/2 systems

When one has a system with no spin and time reversal symmetry, one can conclude that the Hamiltonian entries (in a particular basis, of course) must all be real. Can something be said about the ...
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Question about the discrete symmetries of several fields

Short 4 questions: Is free Klein-Gordon field possess some discrete symmetries? Is it invariant under $P$, $T$ separately? Is free Proca field possess some discrete symmetries? Is it invariant under ...
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Charge, Parity, and Time are considered when talking about symmetries in physics. What about Rotational symmetry?

I've seen Charge, Parity, and Time symmetries talked about, but how come never rotational symmetry? E.g. if the entire universe was rotated 90 degrees, would any physical phenomenon behave differently?...
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Is CPT symmetry a direct consequence of Special Relativity?

I'm wondering about the origin of $\mathcal{CPT}$ symmetry in the Standard Model. The Wikipedia entrance makes me understand it is a direct consequence of Special Relativity. Is it right?
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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 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 ...
Марина Marina S's user avatar
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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 ...
shredEngineer's user avatar
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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 ...
the universe is awesome's user avatar
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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 ...
Марина Marina S's user avatar
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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 ...
Марина Marina S's user avatar
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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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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 ...
Victor Novak's user avatar
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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 ...
ann marie cœur's user avatar
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1 answer
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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 ...
ann marie cœur's user avatar
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1 answer
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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 ...
ann marie cœur's user avatar
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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 ...
ann marie cœur's user avatar
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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 ...
user7077252's user avatar
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1 answer
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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 ...
Gaussian97's user avatar
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1 answer
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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 ...
Physiks lover's user avatar