Disclaimer#
This is only a hand-waving theory from a hobbyist. While I make claims, I may be wrong about the fundamentals of physics, make assumptions, over-simplify, or ignore important elements of particle physics. My goal with this theory is to discuss those ideas and to question particle physics with experts.
If you are a physicist, please contact me and let me know what you think and what I got wrong.
Theory#
Leptons are among the most mysterious and confusing fundamental particles of the standard model because muons and taus seem arbitrary. Electrons and neutrinos serve crucial functions in our universe, but muons and taus appear to be essentially heavier copies of electrons with no obvious unique function. We can identify three reasons why they are confusing:
- They only decay quickly into lighter particles and don’t participate in stable matter
- The specific mass ratios (electron:muon:tau ≈ 1:207:3477) seem arbitrary
- And the reason for having exactly three generations remains unexplained.
My theory is as follows: there are, or were, more generations of leptons, each heavier than the last, until a single extremely massive lepton at the beginning of the universe. I call this single lepton ancestor the “mommion.”
This theory relies on four observations:
- Everything follows the laws of conservation of energy
- The universe has a lepton constant; there must be a balance between the charged leptons and neutrinos
- The leptons we know seem to have a hierarchical relationship
- The universe seems to have started with a big bang
In nature, taus naturally decay into tau neutrinos, muons and muon neutrinos or theoretically muons and antimuons (I don’t think we observed this yet, this is likely extremely rare, but the lepton number does match). As long as the lepton number remains constant, it is allowed. Another requirement is the conservation of energy. The leptons and neutrinos resulting from decay must maintain the same energy as the original lepton of the previous generation through E=mc^2. This conversion can also happen in reverse, but while leptons can decay by themselves, fusing leptons into heavier generations is a lot more difficult since it requires the distinct components (e.g. for a muon: a muon neutrino + (electron + positron, or electron + electron antineutrino)).
It is clear that decaying into lighter charged leptons is a lot easier and more common than fusing into heavier charged leptons. On average, we have observed exponentially more electrons than muons, and exponentially more muons than taus. Their lifetimes follow a similar relationship since electrons are stable, muons have a lifetime of ~10^-6 seconds and taus ~10^-13 seconds. Their masses also follow a similar pattern (electron:muon:tau ≈ 1:207:3477).
When looking at the relationship between the charged leptons, we can infer some sort of family tree with taus at the top, muons in the middle, and electrons at the bottom. The instability of the former two cause the evolution into the stable electrons.
But what if the family tree went a lot further back? As far as I know, we have no proof that it is impossible to fuse a tau neutrino, muon, and muon antineutrino into a new particle, such as a hypothetical biggon. The issue with this approach is that it is incredibly unlikely, and we have not yet observed it. This problem is explored in the next section, but let’s assume that it is possible to fuse taus into biggons.
This biggon would likely have an even smaller lifetime, frequency, and heavier mass than taus at an exponential scale, and, by the same logic, could also be fused into an even heavier lepton such as a hypothetical chonkion. As long as the conservation of energy and lepton number are respected, we are not aware of any laws that would forbid this.
These generations form a tree-like structure of lepton types. We can also infer that this tree is symmetrical due to the lepton number, and a characteristic of symmetrical trees is the root. There must be one original lepton, which I will refer to as the mommion.
This mommion would be the first lepton existing at the very beginning of the universe during the big bang. This lepton would then have nearly instantly decayed into lighter leptons and antileptons, their respective neutrinos and antineutrinos. I will call those leptons firstbons. Interestingly, the mommion’s neutrino would still exist. Since the original lepton number would be 1, there would need to be at least 1 mommion neutrino wandering the universe. It would be theoretically possible for us to observe this neutrino, but practically impossible because neutrinos are nearly impossible to detect, there would only be one mommion neutrino in the universe, and it might have wandered off outside the observable universe since its original decay.
The firstbons would likely have an extremely small lifetime and a great mass, and would also decay into secondbons. This process would continue until reaching the taus, muons, and electrons we know today, and stop at electrons since they are stable. It is unknown how many generations exist. Maybe the mommion decayed straight into taus, maybe there was one generation in between, or maybe there were billions of different particle types. Just like the mommion neutrino, all these unknown particle types would still have their respective neutrinos wandering in the universe.
The purpose of this lepton family is unclear. Whether elementary particles even have a purpose is a matter of philosophy, but this chain of decay could have been instrumental in propagating electrons and neutrinos throughout the universe.
Potential issues#
- Making multiple heavy particles requires lots of energy
It is true that an enormously massive singular mommion would require colossal amounts of energy to decay into still massive leptons, but since the mommion would have existed during the earliest stages of the big bang, this energy would have been available.
- More particles in the final state = lower probability
It is true that there is a lot of freedom in how leptons decay. Many neutrinos, leptons, antineutrinos and antileptons can be created as long as the energy is conserved and the lepton number remains constant. The likelihood of the mommion decay chain to have resulted in a stable universe is probably extremely low, but so are many observable phenomena. One of the biggest questions in physics is “how did we get here?” An extremely small likelihood of a successful universe may be a fundamental aspect of our reality.
- Nature tends toward the minimum energy decay
This is an area where I lack the technical knowledge to elaborate. I don’t know what the original decay pattern might have looked like. How many firstbons did the mommion decay into? And how many secondbons did those firstbons decay into?
Why haven’t we found heavier leptons?#
Why haven’t we found heavier leptons than tau (biggons) to support this theory? Because there are two ways of finding new leptons: by observing the charged lepton, or with its respective neutrino, and neither seems likely to be observed.
We likely haven’t found a neutrino for a biggon or heavier because neutrinos are notoriously difficult to measure since they’re essentially ghost particles (our detectors miss >99.9% of neutrinos), and there simply may not be many neutrinos for leptons bigger than tau. After all, there are orders of magnitude fewer tau neutrinos than muon neutrinos than electron neutrinos.
As for not having found a charged biggon, it may be because it’s orders-of-magnitude heavier and less stable than a tau (like taus are to muons, they decay in ~10^-13 seconds while muons do in ~10^-6 seconds). Energy is likely not the cause because a tau pair requires ~3554 MeV total while the LHC provides ~13 TeV. Another reason could be that creating a biggon requires respecting the lepton number, so a biggon neutrino is necessary, along with either taus and tau antineutrinos, the opposite charge combination, or tau-antitau pairs. Since taus are orders-of-magnitude rarer than muons (which are themselves rarer than electrons), maybe this combination of tau leptons is incredibly unlikely. And as for the ever-elusive biggon neutrino, they are likely exceedingly rare, orders of magnitude rarer than tau neutrinos, and since our detectors miss >99.9% of neutrinos, we likely haven’t observed one yet.