What is Cp violation: Definition and 40 Discussions

In particle physics, CP violation is a violation of CP-symmetry (or charge conjugation parity symmetry): the combination of C-symmetry (charge symmetry) and P-symmetry (parity symmetry). CP-symmetry states that the laws of physics should be the same if a particle is interchanged with its antiparticle (C symmetry) while its spatial coordinates are inverted ("mirror" or P symmetry). The discovery of CP violation in 1964 in the decays of neutral kaons resulted in the Nobel Prize in Physics in 1980 for its discoverers James Cronin and Val Fitch.
It plays an important role both in the attempts of cosmology to explain the dominance of matter over antimatter in the present universe, and in the study of weak interactions in particle physics.

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  1. S

    I 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 arbitrary phases of the CP transformed fields: $$V_{ij} = V^*_{ij} \, e^{i(\xi_W + \phi_{d_j} -...
  2. Y Y Kim

    I What is the meaning of 'CP violation' in the Cronin and Fitch experiment?

    Below are the statements in the "David Griffiths, Introduction to Elementary Particles 2nd Edition, 147~148 p.": Evidently, the long-lived neutral kaon is not a perfect eigenstate of CP after all, but contains a small admixture of K1. The coefficient epsilon is a measure of nature's departure...
  3. A

    A No CP-Violation for coinciding Quark-Masses

    Hello everyone, I know that if two of the quarks (e.g. strange & bottom) had coinciding masses, there would be no CP-violation in the standard model. Apparently the reason lies in the parameters of the CKM-matrix, but I don't understand how to show that. Can someone explain?
  4. mfb

    I T2K sees ~3 sigma evidence for neutrino CP violation

    Publication: Constraint on the matter–antimatter symmetry-violating phase in neutrino oscillations Edit: arXiv: Constraint on the Matter-Antimatter Symmetry-Violating Phase in Neutrino Oscillations Article: Neutrino Asymmetry Passes Critical Threshold Previous measurements already hinted at...
  5. Utg

    A CP Violation & Phase: Explained

    Hello! I have heard many times that CP violation in the SM is due to the presence of phase in the CKM matrix. Can somebody explain how phase is related to CP violation? Thanks!
  6. Wrichik Basu

    I Observation of CP Violation in Charm Decays

    New results from the LHCb experiment have identified a difference in the way charm quarks (##c##) behave as compared to anticharm quarks (##\bar{c}##), when a spatial inversion is taken into account. This so-called charge-parity (CP) violation had previously been observed in strange (##s##) and...
  7. V

    Mixing CP asymmetry calculation

    Homework Statement Consider decay ##\bar{B^0_s}\rightarrow D^+_s \pi^-## and calculate its mixing-induces CP asymmetry. Homework Equations $$\xi_f^{s}=e^{i\theta_{M_{12}}} \frac{A(\bar{B^0_q}\rightarrow f)}{A(B^0_q \rightarrow f)}=\pm e^{-i\phi_s}\frac{...
  8. Gene Naden

    Kaon Physics: CP Violation and Hadronic Matrix Elements

    What would be reasonable preparation for reading the reference Kaon Physics https://arxiv.org/pdf/hep-ph/0401236.pdf I find I do not seem to be ready for this reading. I am familiar with quantum mechanics at the level of Schiff (an old text for first year graduate students) though perhaps rusty...
  9. V

    Is the Left Angle of the CKM Unitarity Triangle Really Pi Minus Gamma?

    Homework Statement I want to proof for $$V_{us}V^{*}_{ub}+V_{cs}V^{*}_{cb}+V_{ts}V^{*}_{tb}=0$$ unitarity triangle that left angle is $$\pi-\gamma$$ (see below picture from my lecture notes). Homework Equations [/B] $$\gamma \approx - arg(V_{ub})$$ $$\beta_s \approx arg(V_{ts})+\pi$$...
  10. Gene Naden

    I CP transformation, charge conjugation and antimatter

    Many discussions cite CP transformation as the exchange of particles for anitparticles. But other places it says that charge conjugation alone is sufficient to turn a particle into its antiparticle. So, the question is, when you exchange particles for anitparticles, is it a CP transformation or...
  11. Gene Naden

    I Direct and indirect CP violation

    The Wikipedia article on CP violation says there is indirect violation in Kaon decay but does not give details. What is the reaction that demonstrates CP violation?
  12. Chronos

    B Evidence for CP violation in the baryon sector

    This paper; https: //arxiv.org/abs/1609.05216, Measurement of matter-antimatter differences in beauty baryon decays, provides the first evidence for CP violation in the baryon sector. This potentially explains a longstanding mystery - why the universe became dominated by matter while anti matter...
  13. mfb

    I T2K: >2 sigma preference for neutrino CP violation

    Presentation at ICHEP Report at university website The main plot is on slide 18: ##\delta_{CP}## seems to be somewhere around -2, with 0 appearing unlikely. In other words, muon neutrinos oscillate more likely to electron neutrinos than anti-muon neutrinos oscillate to anti-electron neutrinos...
  14. Safinaz

    CP violation and allowed interactions

    Hi, My question about CP- violation, but it has many parts, so I appreciate any help about.. First: I know that, any complex coupling leads to CP - violation, so if for example A is a complex scalar, and H is a real scalar, interaction as: A HH will be forbidden if we considered CP...
  15. Anchovy

    Seesaw mech, CP violation, leptogenesis, lept/bary asymmetry

    I'm trying to get my story straight on explaining the universe's matter-antimatter imbalance. So far I understand CP violation in neutrino oscillations (PMNS \delta parameter). And I think I'm right in saying that then a 'leptogenesis' process generates an excess of leptons over antileptons...
  16. T

    Does CP Violation Influence Entropy Through Altered Thermal Radiation?

    Please help me with my confusion. My logic: 1. CP violation causes direct T-violation 2. T-violation breaks Kirchhoff's law of thermal radiation (imagine a rock in a thermal bath of T-violating particles, where absorption and emission rates are different). When I say "radiation", I don't mean...
  17. ChrisVer

    Understanding Indirect vs Direct CP Violation: Explained and Compared

    Can someone explain or give any ref. where I can find the difference between Indirect and Direct CP violations?
  18. JG1009

    CP Violation in Neutral Kaon Decays

    I was recently reading an article that attempted to explain how the results of the Cronin-Fitch experiment illustrated CP violation. (http://hyperphysics.phy-astr.gsu.edu/hbase/particles/cronin.html) However, it wasn't very well explained. Could someone please explain this to me?
  19. vlemon265

    Exploring CP Violation: From Elementary Particles to Everyday Ions

    When my friend asked me about CP violation, I told them about some elementary particles physics. But it seemed they do not have background about this. So is there any daily practical activity that can explain CP violation? Thanks.
  20. E

    Link between CP violation and supersymmetry?

    I have been looking in SUSY and have seen that the CP violation of B mesons into two muons is one of the key facts that has cast further doubt over SUSY. I don t really understand how the CP violation of B mesons is a sign of SUSY issues, so if you are able to clear this up for me that would be...
  21. D

    A question about CP Violation.

    Am I correct in my understanding that the standard model predicts that there should be more matter than antimatter in the universe, but not the dominant proportion that is observed? Is that the basic problem?
  22. Einj

    Penguin diagrams and CP violation

    Hi everyone. I have been studying CP violation in kaon systems. I would like to know is someone can explain why, to leading order, strong penguin diagrams (i.e. involving a gluon) only contribute to the K\to (\pi\pi)_{I=0} amplitude, while the isospin 2 amplitude is given by the electro-weak...
  23. Doofy

    Neutrino oscillation - CP violation obscured by matter effect?

    In long baseline neutrino oscillation experiments, it is possible to investigate the extent of any CP violation by looking at the difference between the rate of neutrino oscillating vs. anti-neutrinos oscillating, ie. we take \Delta P = P(\nu_\alpha \rightarrow \nu_\beta) -...
  24. J

    The link between CP violation and neutrino oscillations?

    I'm trying to understand a bit about CP violation and how it relates to neutrino oscillation. I have a book, "Introduction to High Energy Physics" (Donald Perkins) which says that the probability of observing no change in the flavour of a neutrino is equal to that of an antineutrino of the same...
  25. TrickyDicky

    CP violation and new SM discrepancy at the LHCb

    While we still have no news from Higgs a new discrepancy with the standard model has been spotted by the LHCb experiment: http://profmattstrassler.com/2011/11/16/a-notable-discrepancy-at-the-lhcb-experiment/ I bet next month we'll find Higgs and this discrepancies will go away!
  26. apeiron

    CP violation explained by Kerr metric

    This is an interesting hypothesis that doesn't seem to have been discussed yet. What are its flaws? Mark Hadley at the University of Warwick argues that galactic rotation causes gravitational frame-dragging sufficient to put a local asymmetric twist into spacetime and explain observed CP...
  27. K

    What is CP Violation? Simplified Explanation

    Can anyone explain CP violation in as simplistic a fashion as possible? I just can't understand really in depth versions I am finding online.
  28. F

    Can Matter and Antimatter Be Indistinguishable?

    Is it correct that applying charge conjugation to matter gives us antimatter? This post claims that it is the CP operation that does... http://blogs.uslhc.us/symmetry-in-physics-pt-2-discrete-symmetries-and-antimatter Which is correct?
  29. R

    Which Experiments Proved CP Violation in Particle Decays?

    Hi, I'm currently producing an undergraduate poster on CP violation and I have a few questions: - Was K0 -> \pi++\pi- the decay which proved CP violation in the 1964 Fitch/Cronin experiment, or was it oscillations between K0 and \overline{K}0, or both? (Answered) - How were the decays in...
  30. bcrowell

    String theory and CP violation

    What is wrong with the following reasoning? String theory has diffeomorphism invariance. Since time reversal is a diffeomorphism, string theory is time-reversal invariant. Therefore T and CP violation can't occur in string theory, and string theory can't describe the standard model in the...
  31. N

    Exploring CP Violation: The Truth Behind Particle and Antiparticle Domination

    Please teach me whether it is true or not,that the domination of particles vs antiparticles is caused by the CP violation in nature?
  32. G

    Fermilab's Tevatron finds another CP violation

    http://arstechnica.com/science/news/2010/05/fermis-tevatron-finds-another-bias-against-antimatter.ars Apparantly a paper was just submitted for review about the finding of another CP violation. Link for reference. They seem to think that this one might not be as infrequent as the others...
  33. D

    Noether theorem + CP violation -> Energy is not conserved?

    Based on the Noether theorem http://en.wikipedia.org/wiki/Noether%27s_theorem there is a relationship between conseration laws and symmetries. Conseration of energy and momentum are related to the isotropy of spacetime. However, spacetime is NOT isotropic: CP symmetry is violated...
  34. F

    CP violation: why not in K*, B* vector mesons?

    Experimentalists have measured CP violation in neutral K and B mesons. Everybody is unhappy that so far there are only 2 systems so for which these measurements are possible. (Neutral D mesons are predicted to show such a small effect that it is probably unmeasurable for a long time.) All...
  35. K

    Book reccomendations: CP violation, SUSY and Gravity/EM unification?

    Hi guys, I am doing a dissertation on one of these topics and wondered if anyone knows of some good books that may be good to start out from. Especially if the books focus on the particle physics aspects of these topics. So any books for CP violation and the imbalance of antimatter to...
  36. J

    Question regarding CP violation in the CKM matrix

    Could somebody explain how an imaginary phase in some of the CKM matrix elements represents a CP-violation factor?
  37. V

    Helicity - Experiment proving CP violation

    Please look at the attach file. If we take case a) it proves the C and P are independly violated (neutrinos are left handed) The component of spin along the direction of motion is: -1 for the photon (bosons can have spin + or - 1) -1/2 for the neutrino (fermions can have spin + or -...
  38. M

    Exploring CP Violation in the B System

    Where can I find good information about the CP violation in the B system?
  39. P

    CP violation and element forging

    Hi, I just saw the premier of "Birth of the Universe" on Naked Science (National Geographic) and had a couple of questions as a result, which I'm hoping somebody could answer. First, they said that the reason we have matter and no evidence of anti-matter is because when energy was converted...
  40. C

    Neutral Kaon decay and CP violation

    First of all, many books assume first that K_S and K_L are CP eigenstates. They then tell that by observation that cannot be true. Is that relevant to the CP violation? Why don't the authors just tell that K_L is a mixed state with only a small amount of CP=+1 eigenstate? Second, observing...