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I don't understand why CP violation is insufficient to explain the observed baryon asymmetry? And how do you solve it using the lepton sector?

Key Words:
CKM - Cabibbo-Kobayashi-Maskawa Matrix: in the standard model of particle physics CKM matrix is a unitary matrix which contains information on the strength of flavour changing in weak decays (like in neutrino oscillations).
Neutron electric dipole moment: the neutron electric dipole moment - nEDM is a measure for the distrubution of positive and negative charge inside the neutron which his monopole is zero of course. Like in a dipole, a finite electric dipole moment can only exist if the centers of the negative and positive distribution inside the particle do not coincide.

MNS - Pontecorvo–Maki–Nakagawa–Sakata matrix: In order to explain the neutrino oscillations, one invented the MKS matrix that is a unitary matrix which contains information on the mismatch of neutrinos when they propagate freely and when they take part in the weak interactions. without this matrix, we will not be able to explain the neutrino oscillations.
Neutrino Oscillations: is a quantum mechanical phenomenon whereby a neutrino created with a specific lepton flavor can later be measured to have a different flavor. The probability of measuring a particular flavor for a neutrino varies between 3 known states as it propagates through space.

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  • $\begingroup$ Baryogenesis implies CP violation, but don't assume the converse. There is no baryon-nonconserving term in the Lagrangian of the Standard Model. You'll have to ask the experts on Grand Unified Theories. $\endgroup$
    – Bert Barrois
    Commented Apr 11, 2018 at 13:52
  • $\begingroup$ Can you see if you understand my last question? $\endgroup$
    – Vettel
    Commented Apr 11, 2018 at 14:09
  • $\begingroup$ I don't think you can explain it with leptons either ... unless you assume Majorana neutrinos and exotic gauge bosons that convert leptons to quarks, as in some GUTs. I should also have mentioned a wooly line of argument involving anomalies and nonconservation of axial U(1) charge, but that could mean either helicity change or baryon number change. I'm no expert. $\endgroup$
    – Bert Barrois
    Commented Apr 11, 2018 at 19:03
  • $\begingroup$ This is a pretty nice article. <arxiv.org/abs/hep-ph/0609145> $\endgroup$
    – Bert Barrois
    Commented Apr 11, 2018 at 19:12

2 Answers 2

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When people say there is insufficient CP violation to explain baryon asymmetry, what they mean that is while CP violation is possible in the standard model, it is not inevitable. So the rates of CP violating decays in the quark sector of the standard models aren't high enough to explain the baryon asymmetry in the universe today.

In other words there would be a lot more antimatter in the universe if CP violating quark decays were the only thing that were responsible for matter-antimatter asymmetry. However I believe there is hope in the lepton sector and very specifically in the neutrino sector, which answers your second question I think.

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  • $\begingroup$ Do you have any article that proves that CP quark decays are not enough for the matter-antimatter asymmetry? And can you explain why do you see hope in the neutrino sector? $\endgroup$
    – Vettel
    Commented Apr 9, 2018 at 14:31
  • $\begingroup$ Sure I'll find something but is it okay if I come back later on and edit my comment though? I'm a bit busy at the moment. In the meantime look up the CKM matrix, and the neutron dipole moment. For the lepton sector look up the PNMS matrix and neutrino oscillations. $\endgroup$
    – LUPHYS
    Commented Apr 9, 2018 at 15:22
  • $\begingroup$ sure thanks! I will add an explanation about those terms for the completeness of this conversation. $\endgroup$
    – Vettel
    Commented Apr 9, 2018 at 15:35
  • $\begingroup$ I added keywords in my comment, the problem is that I don't see a difference between CKM matrix and PNMS matrix. $\endgroup$
    – Vettel
    Commented Apr 9, 2018 at 15:55
  • $\begingroup$ A CKM matrix is a mixing matrix for quark states, and a PNMS matrix is for neutrino states. The parameters for the CKM matrix have been experimentally verified through studying particle decays and interactions. The parameters for the PNMS matrix are not as well known experimentally and are for different particles. $\endgroup$
    – LUPHYS
    Commented Apr 9, 2018 at 15:59
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Do you have any article that proves that CP decays are not enough for the matter-antimatter asymmetry? And can you explain why do you see hope in the neutrino sector?

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  • $\begingroup$ Someone can help me? Got stack $\endgroup$
    – Vettel
    Commented Apr 11, 2018 at 16:35

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