# Questions tagged [parity]

Parity inversion P amounts to the sign flip of an odd number of coordinates (reflection). A parity-symmetric theory conserves P; since P²=I, the eigenvalues of P are 1 or -1. May be also used for formally analogous global, discrete, Z₂ symmetries, such as R- or G-parity.

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### QED breaking of parity invariance

QED is invariant under P,T,C for the Lagrangian containing operators of dimension equal or smaller than 4. I was wondering, what are the possible parity-breaking terms in QED with dimension smaller or ...
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### Position expectation values in quantum harmonic oscillator

I have read that $<x^n>$ is zero for all odd values of $n$ in any state of quantum harmonic oscillator. What is the reason behind this? I can imagine for $n=1$ ( because wavefunction is ...
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### How to comprehend the fact that parity is an improper rotation in the odd dimension, but not in the even dimension, physically?

Some "clarification" To begin with, I'm not even talking about relativity so, in the following, rotations always act on the Euclidean space or only the space subpart of the Minkowski space. ...
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### Why parity conserves in fermi transition?

Beta decay is a weak interaction process and in weak interaction parity doesnot conserve , then why in fermi transition initial and final parties of the nucleus is conserved ?
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### Parity in Effective Lagrangians

Given the following Lagrangian $$\mathscr{L} = c\frac{g}{m}\bar{\psi}_A\Gamma_5\gamma^\mu\psi_B (i\partial_\mu)\phi$$ where $\Gamma_5 \in \{\gamma_5, 1\}$, for two spin one-half particles $A$ and $B$ ...
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### Parity and intrinsic parity definitions

The action of parity operator on wavefunctions is defined as a reflection in the origin $$\hat{P}\Psi(\boldsymbol{r},t)=\Psi(\boldsymbol{-r},t)$$ In particle physics, though some books define its ...
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### How is the parity transformation defined? Especially for vector or tensor fields?

If I have a scalar field \begin{align} f: \mathbb{R}^3 &\rightarrow \mathbb{C}\\ (x, y, z) &\mapsto f(x, y, z) \end{align} We can define an operator $P$ that takes a function like $f$ and ...
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### Missing parity of free particle [duplicate]

in this Definite Parity of Solutions to a Schrödinger Equation with even Potential? post in David Z's answer it's stated that the eigenfunctions have parity if the potential has parity/if \$[H,P]=...
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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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### Is a magnet and bouncy balls a case of parity violation?

This may well be a very odd question; however, I'm currently studying parity violation and it came to mind that, if a Cobalt-60 atom decaying by the weak force and emitting more electrons opposite the ...
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### Confusion over Feynman’s description of the Wu experiment for parity violation

In his lecture on symmetry in physical law, Feynman said: Using a very strong magnet at a very low temperature, it turns out that a certain isotope of cobalt, which disintegrates by emitting an ...
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### Why are right-hand rules not changed to left-hand rules under a parity operator?

Right-hand rules are, of course, merely convention; however, if we are to decide upon using a right-hand rule to obtain directions in one coordinate space, then why should we not use the left-hand ...
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