Questions tagged [cp-violation]
is a property of a system or theory where the combined charge conjugation (replacing particles with their anti-particles) and parity (reversing the sign of every vector, equivalent to reflecting the system through the origin) operations yield non-equivalent results. Only the weak interaction is know to produce CP-violation.
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$CP$-violation in neutral $K$-mesons mixing [closed]
I am studying $CP$-violation in the mixing of neutral $K$ mesons $K^0$ and $\bar{K}^0$.
I have a task to show that $CP$-violation in the neutral kaon system is absent in the limit $m_s = m_d \gg m_u$. ...
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How does parity conservation follow from the Wu experiment?
The Wu experiment shows how parity symmetry does not hold for the weak force. However, how does this proof that parity conservation also doesn't hold?
If my understanding is correct, the absence of ...
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Noether's Theorem application [duplicate]
So I know that Noether's theorem has a symmetry that corresponds to a conservation law.
I was wondering what quantity is conserved in charge conjugation symmetry.
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Axion production from vacuum realignment and the strong CP problem
I am trying to understand axions as a possible candidate for dark matter. My understanding of one of the mechanisms by which energy could up in the axion field is by an initial misalignment between ...
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Jarlskog Invariant
Jarlskog Invariant is directly proportional to CP violation. I want to know why it's called "an invariant". What is the nomenclature of the Jarlskog Invariant?
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Can we save Feynman's martian rendez-vous with $CP$ violation?
There's a short part in The Feynman Lectures where he explains the why you should never shake a martian's left hand. He introduces a "martian" who we can only communicate with in some ...
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Does CP symmetry dictates that a particle and its antiparticle behave the same when moving in opposite directions and how can I observe CP asymmetry?
I have started reading in particle physics very recently. I have been reading a bit about tau particles, and I came across the idea of CP symmetry and how it’s violation may present an explanation for ...
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QFT symmetry breaking and CP violation
Since the weak interaction violates CP symmetry but electromagnetism doesnt,does it mean that the electroweak fields also violates CP symmetry?Can a field which violates some symmetry be the product ...
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Fixing $CP$ phases to cancel CKM phases
When we try to see if the weak sector is $CP$ invariant, we $CP$ transform all the fields in the charged interactions terms and we get a condition involving the elements of the CKM matrix and the ...
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Why the long lived Kaon can not decay into two pions?
The short-lived and long-lived states of kaon $|K_1>$ and $|K_2>$ respectively have the following compositions if they are the eigen states of CP parity:
$|K_1> = \frac{|K^0>\:-\:|\bar{K^0}...
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CP Violation for Leptogenesis
I'm interested in calculating the CP violation factor used in leptogenesis calculations. Specifically, I want to calculate eq. 4 - 5 in this paper. I will use the Lagrangian (1),
$$
\mathcal{L}
\...
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Experimental searches for magnetic quadrupole moment
My professor mentioned that a particle with an intrinsic magnetic quadrupole moment would be CP violating in an analogous manner to how a particle with an electric dipole would be evidence for new ...
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Strong $CP$ problem and fine tuning
I have worked my way up to and through Srednicki's Quantum Field Theory chapter 94 and was also doing some reading on the internet about the strong $CP$ problem.
Wikipedia's entry on the strong $CP$ ...
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If the protons in a nucleus were replaced by antiprotons and the electrons by positrons what fundamental change would be introduced into the universe?
Exactly what the question says;
If all the protons and electrons in every single atom in the universe were swapped for their anti-particles, what would essentially change?
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how can the virtual fermionic lines be vertical in kaon mixing feynman diagram?
how can the virtual fermionic lines be vertical in kaon mixing Feynman box diagram (or in general)? Wuouldn't this mean that they travel a distance $\neq 0$ in 0 time?
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On neutral Kaon mixing
Kaons are not eigenstates of $CP$:
$$
CP|K\rangle =|\overline K\rangle\\
$$
Why do we need to mix them?
One answer I read is "since they both decay into $2$ or $3$ pions". Couldn't they ...
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Does $CP$-violation mean $CP$-odd?
This might be a very simple question but I'm doing some reading into the Higgs boson and $CP$-symmetry breaking. I've seen the terms $CP$-even and $CP$-odd terms in the Hamiltonian floated around and ...
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If the universe was dominated by antimatter instead of matter, would we physically notice?
I read that antimatter and matter are identical aside from their opposite charge and quantum number. Of course, the mystery of why matter dominates in our universe is an active field of research. But ...
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Working through the solution of the Ozma problem
I’m trying to work through the Ozma problem and the Wu experiment to get a better handle on parity and I’m being tripped up by something which is almost certainly trivial.
I can explain negative ...
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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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Why is the neutron electric dipole term CP violating?
I have heard that a term of the form $\bar{q}\sigma^{\mu\nu}q F_{\mu\nu}$ is CP violating but looking at any Textbook (e.g. Peskin Schröder) one can see that the CP transformations are the following:
$...
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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 ...
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About the recent bounds on the baryon asymmetry
While I'm studying the baryon asymmetry, the ratio of baryons number to the photons number in the universe - some times is called baryon density - $: \eta= n_b/n_\gamma$
I have found many experimental ...
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What were the main results of the BaBar Experiment?
I have been trying to find a review of the BaBar experiment results for quite some time now. Can anyone link a few papers which illustrate what has been achieved so far?
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How can a quantum theory (eg. particle physics QFT) governed by Schroedinger eqn. break the $T$ symmetry (or $CP$) microscopically at all?
Why and how can a quantum system (like the quantum vacuum of our universe) governed by the Schroedinger equation break the time-reversal $T$ symmetry (or $CP$ symmetry) microscopically at all?
p.s. ...
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What is the CKMFITTER plot?
I am struggling to understand the CKMFITTER plot which is attached here. Please, someone, try to explain to me what are all these color bands. What are their meanings? Why one band is circular in ...
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What are the implications of violation of the unitarity of CKM matrix?
What are the physical implications of such observation?
In other words, why is everybody concentrating on the violation of the unitarity of the CKM matrix?
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Amount CP violation needed
It is widely known that the CP violation provided by the Standard Model ( SM )is insufficient to explain the baryon asymmetry that we observe. However, I never came across any quantitative ...
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CP violation phases counting in neutrino flavor mixing sector with $N$ sterile neutrinos
In the quark sector, the CKM matrix is obtained from (see p.723 of Peskin QFT)
$$
V_{CKM} =U_u^\dagger U_d = \begin{bmatrix} V_{ud} & V_{us} & V_{ub} \\V_{cd} & V_{cs} & V_{cb} \\
V_{...
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PMNS matrix versus CKM matrix -- how precise is the analogy?
PMNS matrix is said to be the matrix for the neutrinos as the CKM matrix for the quarks.
See https://en.wikipedia.org/wiki/Pontecorvo–Maki–Nakagawa–Sakata_matrix#The_PMNS_matrix
However, I am ...
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Electric dipole moment (EDM) and magnetic dipole moment (MDM): CP violation in neutron
The neutron magnetic dipole moment (MDM) is the intrinsic magnetic dipole moment of the neutron.
Under parity P, the MDM does not change direction.
Under time reversal T which is equivalent to CP, ...
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Theta terms observable effects for $SU(3)$, $SU(2)$ and $U(1)$ in the standard model [duplicate]
In p.726 of Peskin QFT, it says:
The theta terms are total derivative, that terms involving $SU(2)$ and $U(1)$ have no observable effects.
However for the strong $SU(3)$, it costs a strong CP ...
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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 &...
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In this example, how can we have CP conservation with C violation?
Consider a simple two-body decay process $X\to Y+Z$ where $X$ is a boson, and $Y,Z$ are fermions. If $C$ is violated, $$\Gamma(X\to Y+Z)\neq \bar{\Gamma}(\bar{X}\to\bar{Y}+\bar{Z}).\tag{1}$$
However, ...
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What happens to $\theta_{CP}$ for ${\rm U}(1)$ in the Standard Model?
I'm trying to understand how we can get rid of the ${\rm U}(1)$ theta term (whose $\theta$ I call $\theta_1$) in the SM.
In Schwartz's QFT textbook he writes
Before discussing the strong CP phase ...
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Regarding matter-antimatter asymmetry
We all know that the asymmetry between matter and antimatter is a big puzzle in physics. But I don't know why one expects matter-antimatter symmetry in the first place? As in, is there a fundamental ...
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Electric dipole moment (EDM) and dilogarithm with complex argument
In the paper https://arxiv.org/abs/1310.1385 it's calculated the electron electric dipole moment (eEDM) in terms of a function $f_1(x)$ defined as
$$
f_1(x) = \frac{2x}{\sqrt{1 - 4x}}\left[Li_2\left(...
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A pair-universe solution to CP-violation problem [closed]
Disclamer
Before I continue, I'd like to state clearly that I'm by no means an expert in this field. What I regularly do is read popular literature on this topic (if such a thing could be considered '...
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Electric dipole moment (EDM) and CP violation
It's well known that a non-zero value for the electric dipole moment (EDM) would imply CP violation. If we consider the interaction Hamiltonian of an EDM $d$ with an electric field $\vec{E}$,
$$
H = -...
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Are antileptons and antibaryons linked?
The recent news about the T2K experiment got me thinking: is there any linkage in the Standard Model between the matter and antimatter categories across the families of Standard Model particles? Are ...
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Neutrino Oscillation Transition Probability With CP Violation
The transition probability for neutrino vacuum oscillation is
$P_{\nu_{\alpha}\rightarrow\nu_{\beta}}=\delta_{\alpha\beta}-4\sum_{k>j}\text{Re}\left[U^{*}_{\alpha k}U_{\beta k}U_{\alpha j}U^{*}_{\...
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What do you mean by in the mirror world?
I was trying an attempt to replicate Wu experiment mentally when I heard the term mirror world kept popping ups, why should we care what happens inside the mirror world? Is it a math thing?
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What is the antiparticle corresponding to the left neutrino $\nu_L$?
What is the antiparticle corresponding to $\nu_L$ ?
-According to this thread :
What distinguishes the behaviour of particle from its antiparticle: C violation or CP violation?
"The operation that ...
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How is a T-violation inherited in a QFT?
CP violation
In quantum field theory (QFT), ${\rm CP}$ symmetry or ${\rm CP}$ violation is a property of the Lagrangian. For a ${\rm CP}$ violating QFT, in general, the absolute square of the Feynman ...
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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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CP violation and matter- anti-matter asymmetry
It is clear that C violation is a must for matter-antimatter asymmetry. But why CP violation also necessary for the same?
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$CP$ Invariance of Yang-Mills Vacua in Electroweak Theory
It is well know that quantum Yang-Mills theory has a periodic vacuum structure. Consider electroweak theory. For a single generation of fermions, the theory is CP invariant. I would like to know if ...
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Why does the axion solve the CP problem?
I don't understand why the CP violating term in QCD vanishes when we introduce the axion. The term is $$\left(\frac{a}{f_a}+\theta\right)G\tilde{G}$$ It is claimed that $\left\langle a\right\rangle=-\...
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Is there violation of energy conservation when a particle transforms to its anti-particle, for example $B^0\to\bar{B}^0$, or $K^0\to\bar{K}^0$
additive information : $B^0$ and $\bar{B}^0$ don't have the same mass,
$K^0$ and $\bar{K}^0$ don't have the same mass.
is there energy violation?
if yes, is the key explanation of this coming from the ...
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CP violation measurement
I have a question regarding the measurement of CP Violation in experiment. How is parity measured in an experiment? I know that in the direct measurement of CP violation we look at a particle process ...
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