# Why an electron and a positron should have the same lifespan?

According to Particle Data Group:

source: data

Particles and their antiparticles (i.e. antimatter) have the same lifespan.

The electron/positron for example have a minimum of 6.6E28 yr. This was experimentally verified for the electron here in this 2015 paper: paper (see also here in this story cover article IOP)

Nevertheless, there is no any experimental verification of why stable antiparticles like the positron should have the same lifespan with their normal particles counterparts (e.g. electron)?

Seems to me that this is more like a theoretical ansatz.

Is there any experimental verification ever for the above?

This might be crucial information. Maybe besides charge and chirality there is something else going on concerning the interaction of stable antiparticles with vacuum space that could explain why matter is dominant in our Universe and not annihilated with the production of equal amount of matter and antimatter during the Big Bang?

• It is a theoretical ansazt and follows from the Standard Model. You yourself say that it is experimentally verified with a minimum of 6.6E28 years. So there is nothing to invalidate the ansatz. What more verification do you want? Oct 17 at 12:21
• The 2015 experimental paper was for the electron not the positron as far as I know. I believe it is important to verify experimentally the lifespan of stable antiparticles because if the equality is violated this could be a potential explanation of the matter-antimatter unsolved problem. Oct 17 at 12:43
• What do you mean by “an experimental verification of why …” Experiments do not tell us the answer to why question. They verify - or contradict - the predictions of theoretical models, and these models are where why questions may find an answer (at least to the extent that why questions are answerable at all). Oct 17 at 12:53
• In absence of experimental evidence for the positron lifespan, why we have decided that the positron has the same lifespan with that of an electron? The question is targeted towards the theoreticians. Is there a definitive theoretical proof for that? What other laws are violated when it is found that these two don't have the same lifespan? IMO this subject is worth investigating. Oct 17 at 13:02
• It is a direct consequence of the Standard Model (SM) as I already mentioned. There are many more and possibly simpler experiments to try to invalidate the SM. Oct 17 at 16:09

In the table, all the particles except the electron and positron (and the proton-antiproton) are particles which decay. The decay rates allow the calculation of the lifetime of these particles and that is what is shown on the last column. Note that the electron and positron have a reference (1), which you have not copied for us, and the link you give is not from the publication itself, just for the image.

(1) must be pointing out that the rest of the numbers are lifetimes derived from experiments measuring the decays of the particles, but for the electron and positron this must be the lower lifetime limit from experiment . The limits are entirely due to experimental and calculational errors, not to the lifetime, if there is one; the number says that the electron is stable within experimental errors.

Within the standard model, the lifetimes of antiparticles are the same as for particles, and this has been checked by experiment.

But even if one could have a corresponding experiment for positrons the experimental errors would say nothing about the axiomatic symmetry on lifetimes between electron and positron. The experiments for the positron would be different and much more difficult to perform so the experimental errors would be different, but this would be irrelevant for testing the standard model axiomatic assumptions.

The same is true for what is given on the right for the proton antiproton, that might decay as some models predict. It is the proton whose lifetime can be checked very accurately. Antiprotons carry the problems of production and easy annihilation in any experimental setup.

• It is definitely worth asking what is the highest known lower bound on the positron half-life that is obtained directly (and without passing through symmetry arguments). It certainly won't be as ridiculously high as the $10^{28}$ yr figure given for electrons. Oct 17 at 19:32
• FYI the reference [1] can be found by following the first link to the data where you can find the link to [1] Oct 17 at 21:11
• @EmilioPisanty , sure, but that is another question. Oct 18 at 3:20
• @fyrepenguin thanks. Oct 18 at 3:29
• @PM2Ring right, I did not notice blinded by the weak decay particles :). I will edit. Oct 18 at 9:16