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1answer
34 views

C-parity violation evidence

I know about the CP-violation experiments from the 60's and the P-violation from the 50's. But, is there a similar experiment which displays (perhaps historically in the same way as the experiements ...
0
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1answer
75 views

Schroedinger and Klein-Gordon equation and their complex conjugate

Let's consider the Schroedinger equation \begin{equation} i\hbar\frac{\partial}{\partial t}\psi=-\frac{\hbar}{2m}\nabla^2\psi \end{equation} If I have a wavefunction $\psi$ as a solution, then its ...
4
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1answer
30 views

Is Charge Conjugation Representation Dependent?

I'm having a problem understanding section 7 of this paper: http://arxiv.org/abs/1006.1718 The author defines the commonly know $\Psi^c$ as $\textit{C}\Psi \textit{C}^{-1}=\eta \hat{\Psi}$ in ...
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1answer
12 views

Conservation of $C$-Parity and $P$-parity

Under what situations are $C$-Parity $C=(-1)^{L+S}$ and/or $P$-parity $P=-(-1)^L$ conserved? ( $L$ here is the relative angular momentum and S is the total intrinsic spin). It would make sense that ...
1
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1answer
142 views

Symmetry properties of gamma matrices

While reading a paper on supersymmetry i faced the following problem. Its about the symmetry property of charge conjugation matrix in different space time dimension. The charge conjugation matrix is ...
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0answers
20 views

Charge-conjugation of Majorana pair

I was reading this article about WIMP pair annihilation. At page six the author says that under charge conjugation a state of Majorana particles with orbital angular momentum $L$ and spin angular ...
3
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1answer
49 views

How to determine if interaction is allowed?

I'm trying to determine if the reaction $$n\rightarrow p\pi^-$$ is allowed. First of, this doesn't list this as one of the decay modes of the neutron, so I suspect that it should not be allowed. ...
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0answers
35 views

Charge conjugation and the conserved charge for the Dirac field

So, while reading Peskin & Schroeder's chapter on the Dirac field, they claim that the charge conjugation operator has the following properties: $$ \mathcal{C}\psi(x) \mathcal{C} = -i \gamma^2 \...
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0answers
31 views

Confused about anti-fermion notation

Classically anti-fields are obtained by charge conjugation, right? But sometimes authors label hermitian conjugated fields as anti-particles (or barred fields in Dirac language). But h.c. and charge ...
3
votes
1answer
70 views

Charge Conjugation for $SU(N)$?

For $SU(2)$ the charge conjugation operator $C$ reads explicitly $$ C \Psi = i \sigma_2 \Psi^\star ,$$ where $\sigma_2$ is a Pauli matrix. What is the generalized charge conjugation for $SU(N)$?
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0answers
69 views

Definition of the charge conjugation operator

My question will be a bit provocative, I hope it will attract more interest (and hopefully no downvoting). I introduce the following notation: $u(p)\exp(-ipx)$ positive energy solution $v(p)\exp(ipx)$...
1
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2answers
114 views

Why do we assume that particles and their antiparticles have the same half-life?

Has it been proven experimentally? What would the consequences be if their half-lives were different?
5
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1answer
393 views

Antiparticles, charge conjugation and chirality

(Why/how) are antiparticles and charge-conjugates different things? I am trying to understand the effect of discrete symmetries on spinor fields (neutrinos in particular). In the article, Dirac, ...
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0answers
126 views

Charge conjugation of particle and anti particle system

I've seen in the literature that quark and anti-quark (or in general, fermion and anti-fermion) bound states, such as the neutral pion or positronium, have C eigenvalue of (-1)^(L+S), where L is their ...
2
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2answers
155 views

Does charge conjugation affect parity?

Notice that these transformations do not alter the chirality of particles. A left-handed neutrino would be taken by charge conjugation into a left-handed antineutrino, which does not interact in the ...
0
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0answers
64 views

Plane wave solutions of the Majorana equation

Let u(p) and v(p) be the plane wave solutions of the Dirac equation with positive respectively negative energy. In case of a solution of the Majorana equation the charge-conjugated solution is ...
4
votes
1answer
599 views

Can bosons have anti-particles?

Can bosons have anti-particles? In the past, I would have answered this question with a yes, primarily because I can imagine writing down a QFT for complex scalars that has a U(1) symmetry that ...
4
votes
1answer
102 views

How is $J^{PC}$ value experimentally determined for new types of particles?

How is $J^{PC}$ value experimentally determined for new types of particles? For example, this paper says ... Angular correlations in B+→X(3872)K+ decays, with X(3872)→ρ0J/ψ, ρ0→π+π− and J/ψ→μ+μ−, ...
0
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1answer
126 views

What's difference between C parity and charge?

I know C parity as an operator : $$ C\psi=\pm\psi $$ has two eigenvalues like parity operator P. But what I wonder is, i.e, is it true to say for a negative charged particle has (-) eigenvalue? If not ...
1
vote
1answer
397 views

Invariance of the QED Lagrangian under charge conjugation

Is it true that the QED Lagrangian $$\mathcal{L} = \bar{\psi}(i\gamma^\mu D_\mu-m) \psi $$ is invariant under charge conjugation? $$\begin{align} \psi &\mapsto -i(\gamma^0 \gamma^2 \psi)^T\\ \...
6
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0answers
351 views

Charge conjugation and chirality

while I was reading about charge conjugation I found some (apparently) contradictory facts. For example Itzykson & Zuber says (page 153) "Up to a phase, $\cal C$ interchanges particles and ...
-1
votes
1answer
148 views

Invariance under charge conjugation… Or not?

I have read some paper which says that the electroweak Lagrangian includes these terms like $\bar{\psi} \gamma_a\gamma_5\psi$ and $\bar{\psi} \gamma_a \psi$. They violate charge conjugation symmetry. ...
8
votes
2answers
247 views

Can we treat $\psi^{c}$ as a field independent from $\psi$?

When we derive the Dirac equation from the Lagrangian, $$ \mathcal{L}=\overline{\psi}i\gamma^{\mu}\partial_{\mu}\psi-m\overline{\psi}\psi, $$ we assume $\psi$ and $\overline{\psi}=\psi^{*^{T}}\gamma^{...
5
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0answers
110 views

Is $\overline{\psi_{L}^{c}}\psi_{R}^{c}=\overline{\psi_{R}}\psi_{L}$ true for two different spin 1/2 fermions?

In the context of seesaw mechanism or Dirac and Majorana mass terms, one often see the following identity $$ \overline{\psi_{L}^{c}}\psi_{R}^{c}=\overline{\psi_{R}}\psi_{L}. $$ Here, I am using 4 ...
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0answers
118 views

Are Lifshitz and Berestetskii right in this case?

In the Quantum electrodynamics book (look at the problem) its authors Lifshitz and Berestetskei claim that operator of charge conjugation $\hat {C} = -\alpha_{2}$ in Majorana basis transforms as $\hat ...
2
votes
1answer
763 views

Majorana equation in two forms

Let's have two forms of Majorana equation. First form (standart or spinor representations of gamma-matrices). $$ i\gamma^{\mu} \partial_{\mu}\Psi - m\Psi = 0, \quad \Psi = \Psi_{c} = \hat {C} \bar {...
5
votes
1answer
763 views

Derivation of a gamma matrices identity

While studying Srednicki's book on quantum field theory, I encountered a particular identity that is of interest to me (equation 36.40): $$\mathcal{C}^{-1}\gamma^\mu\mathcal{C}=-(\gamma^\mu)^T$$ where ...
4
votes
2answers
333 views

C, T, P transformation mistakes in ``Peskin&Schroeder's QFT''?

I suppose the right way to do C (charge), T (time reversal), P(parity) transformation on the state $\hat{O}| v \rangle$ with operators $\hat{O}$ is that: $$ C(\hat{O}| v \rangle)=(C\hat{O}C^{-1})(C| ...
5
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2answers
1k views

Charge-conjugation of Weyl spinors

I am having trouble reconciling two facts I am aware of: the fact that the charge conjugate of a spinor tranforms in the same representation as the original spinor, and the fact that (in certain, ...
7
votes
1answer
415 views

Shouldn't Charge Conjugation be known as “positive/negative frequency symmetry”?

I know that charge conjugation exchanges the creation (or annihilation) operators of the particles with those of the anti-particles and therefore merits the name charge conjugation. However, if ...
6
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1answer
2k views

Proof of Furry's theorem

i was wondering if anyone could give an explicit calculation or show a link that shows the proof to Furry's theorem. showing how the vacuum expectation value of any odd number of electromagnetic ...