The weak force, and neutrinos which only interact via the weak force, are the most chiral parts of the Standard Model of Particle Physics. I am deeply skeptical of any beyond the Standard Model physics proposal which contains right handed neutrinos.
It has been claimed in a number of publications that neutrinos can exhibit chirality oscillations. In this note we discuss the notion of chirality and show that chiral neutrino oscillations in vacuum do not occur. We argue that the incorrect claims to the contrary resulted from a failure to clearly discriminate between quantum fields, states and wave functions. We also emphasize the role played in the erroneous claims on the possibility of chirality oscillations by the widely spread misconceptions about negative energies.
Evgeny Akhmedov, "On chirality and chiral neutrino oscillations" arXiv:2505.20982 (May 27, 2025).
4 comments:
Axion-like
particles (ALPs) with broad-ranging masses and couplings are introduced. ALPs exist in any
model with a spontaneously broken global symmetry. They can be viable candidates for a DM
particle [10, 11, 12], and can also explain the observed matter-antimatter asymmetry [13, 14]. In
addition, ALPs provide the possibility to explain the anomalous magnetic dipole moment of muon
[15, 16], the anomalous decays of the excited Beryllium 8Be∗ [17, 18], and the excess of events
observed in the rare K mesons searches performed by the KOTO experiment [19]. There are
proposals that the neutrino mass problem may also be solved by ALPs through a coupling to
neutrinos [ 20, 21, 22]. Being motivated by such possibilities, the ALP parameter space has been
extensively probed to date by collider searches, low-energy experiments, cosmological observations,
etc. [23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42].
Light ALPs with masses below the threshold of the electron pair production (≈ 1 MeV)
predominantly decay into a pair of photons. Other decay channels, e.g. decays into leptons and
hadrons, become available for heavier ALPs. ALPs with large enough masses decay promptly after
https://arxiv.org/pdf/2505.21305
There are
proposals that the neutrino mass problem may also be solved by ALPs through a coupling to
neutrinos [ 20, 21, 22].
you prefer alp?
@neo This paper is making a lot of poorly supported or since contradicted claims (even if someone, somewhere has come up with some hairbrained papers that supports these claims).
"ALPs exist in any model with a spontaneously broken global symmetry."
False.
"They can be viable candidates for a DM particle"
True - so far. It is one of the least strongly ruled out candidates for a DM particle.
"and can also explain the observed matter-antimatter asymmetry"
False.
"ALPs provide the possibility to explain the anomalous magnetic dipole moment of muon"
False. Indeed, the latest muon g-2 data strongly disfavors all low to medium energy BSM physics, including ALPs.
"There are proposals that the neutrino mass problem may also be solved by ALPs through a coupling to neutrinos"
Very doubtful and tentatively disfavored by astronomy data.
"the ALP parameter space has been extensively probed to date by collider searches, low-energy experiments, cosmological observations, etc."
Much less well than other proposed DM candidates. And, of course, there are no affirmative detections of them in any channel. To the extent that this is true it is an argument against ALPs.
"Light ALPs with masses below the threshold of the electron pair production (≈ 1 MeV)
predominantly decay into a pair of photons."
There is no evidence that this is true, and if ALPs are DM candidates, it shouldn't be true. DM candidates should be more stable.
"Other decay channels, e.g. decays into leptons and
hadrons, become available for heavier ALPs. ALPs with large enough masses decay promptly after"
If they are that heavy, they aren't ALPs, pretty much by definition.
so how to get neutrino mass problem
@neo Not sure, but neither Majorana mass nor a see-saw mechanism seem right. There are technical issues with a Higgs mechanism as well. My working hypothesis is that it comes from self-interactions via the weak force and W boson interactions, but those are both very tentative possibilities and aren't rigorously worked out. A rigorous solution that is better than the currently leading proposals has not yet been proposed.
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