Anti-photon, anti-neutrino

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Reminder 1: there are no right-handed neutrinos

Reminder 2: only left-handed fermions (and right-handed anti-fermions) participate in “weak nuclear” interactions. This violates P-symmetry which is the symmetry under parity transformation. Electromagnetic and strong nuclear forces do not differentiate left-handed and right-handed particles but the weak nuclear force does.  Parity transformation changes helicity (changes neutrino into anti-neutrino). Neutrino and anti-neutrino behave differently under weak nuclear interactions. This is why neutrinos are said to violate P-symmetry.

Reminder 3: elementary particle facts

I came across a Q&A prepared by the University of Illinois at Urbana-Champaign Physics Department. We need more tutorials like this.

https://van.physics.illinois.edu/qa/listing.php?id=1153

Caveat:

In the tutorial (link shown above) there is a discussion of photon-photon collisions. In the blogpost titled “On the photon frequency” I mention that photons do not interact with other photons, they pass through each other because photons do not have electric charge.

In the blogpost titled “On the photon-photon interaction“, I remind readers that in the presence of strong electric and magnetic fields energetic photons may result in electron/positron pairs (real or virtual). There are many other possibilities: virtual quarks or leptons (and the antiparticles associated with them) may be created as well. These entities interact (via electromagnetic force or via strong-nuclear force) and then transform into real photons again. The entire process would have the appearance of photon-photon scattering. This is an extremely rare process. Only few photons will interact in such a way.