All Questions
Tagged with standard-model parity
41
questions
-3
votes
1
answer
100
views
Parity transformation of the $\pi^{0}\rightarrow\gamma\gamma$ process
I want to prove that the amplitude
$$\mathcal{M}^{\mu\nu}=\epsilon^{\mu\nu\alpha\beta}q_{1\alpha}q_{2\beta}$$
is violating parity. Here $q_{i=1,2}$ are the external momenta of the photons. The total ...
- 477
5
votes
1
answer
76
views
$ \pi^0\to \gamma\gamma$ parity conservation
Let's consider the decay process $\pi^0\to \gamma \gamma$. After we spontaneously broke the chiral symmetry of QCD coupled to an abelian gauge field $A^\mu$, we end up with the Goldstone boson ...
- 357
3
votes
0
answers
75
views
Parity violation via symmetry breaking?
(Apologies in advance for a poorly formulated question.) In Physics, if something can be equally well found in state A or state B, but for whatever reason is in state A, we sometimes observe the ...
- 2,921
1
vote
0
answers
54
views
Do GUT's really explain parity violation?
Every book on the Standard Model introduces early on the concept of left and right-handed quantum fields, defined as
\begin{align}
(\psi_L)_{\alpha} = \left(\frac{1-\gamma_5}{2}\right)_{\alpha \beta}\...
- 131
1
vote
1
answer
55
views
Do the WI coupling constants change sign under $C$?
I am trying to understand discrete symmetries in the SM, and I have some troubles in understanding why the CC interaction violates CP. In my (badly written) notes it's said that, taken two fermonic ...
- 477
1
vote
1
answer
81
views
Why is the vacuum state $|0\rangle$ invariant under parity?
I was studying the leptonic pion decay $\pi\rightarrow l\nu_{l}$, and usually the amplitude is computed by
$$\mathcal{M}(\pi\rightarrow l\nu_{l})=-i\frac{G_{F}}{\sqrt{2}}V^{*}_{ud}\langle0|\bar{d}\...
- 477
2
votes
2
answers
177
views
Does particle parity play any role in matter anti-matter annihilation?
If a left handed electron and a right handed antimatter electron were to meet, would they still annihilate?
In the same way, if a left handed electron and a left handed antimatter electron meet, will ...
1
vote
1
answer
564
views
$C$-parity in $\pi^0\pi^+\pi^-$ system
I'm studying the conservation of the quantum number in the decay $\omega^0\rightarrow\pi^0\pi^+\pi^-$. Since
$P(\omega^0)=-1$
and
$P(\pi^0\pi^+\pi^-)=P(\pi^0)P(\pi^+)P(\pi^-)(-1)^{L_{+-}}(-1)^{L_{(+-)...
- 147
25
votes
3
answers
3k
views
Why do we care about chirality?
I'm trying to figure out what's the importance of chirality in QFT. To me it seems just something mathematical (the eigenvalue of the $\gamma^{5}$ operator ) without any physical insight in it. So my ...
- 761
0
votes
1
answer
90
views
Finding $J^{PC}$ for multiparticle final state
Funnily enough, I have a question about an assertion made in one of my own papers (it was made by one of my collaborators, not me).
At the bottom of pg. 8 it is stated that
... [T]he final state ...
- 4,780
2
votes
1
answer
518
views
Parity and time reversal symmetries in QFT and the Standard Model
The parity transformation $\mathcal{P}$ and the time-reversal transformations $\mathcal{T}$ are defined as follows :
\begin{equation}
\mathcal{P}=
\begin{bmatrix}
1 & & & \\
& -1 &...
- 1,044
3
votes
0
answers
113
views
Parity of Particles
Like charge, spin,etc.. Parity is an intrinsic property of the particle. As I read in Grifith's introduction to elementary particles book , he states parity mathematically but I am not able to see it ...
- 61
1
vote
1
answer
100
views
Higgs boson positive parity, and zero spin
Can we predict the positive parity, and zero spin of the Higgs boson from
the decay mode: 𝐻 → 𝛾𝛾
- 11
0
votes
1
answer
723
views
Parity of neutral leptons
Why we consider Hadrons as the eigenstate of parity operator? In doing so we assign each hadron a quantum no. +1 or -1. What about the parity of leptons, and more specifically parity of neutrino? The ...
- 226
3
votes
1
answer
1k
views
Maximal Parity violation in Weak interactions
In 1956 Lee and Yang proposed parity violation of the weak interactions to explain the $\theta-\tau$ puzzle.
The following year, 1957, Madam Wu and collaborators found that in the $\beta$ decay of ...
