What is the smalest particle?

Answer 1

So far the smallest particle discovered is "Neutrino"

You might get a lot of answers saying a quark or something else it is wrong. Since not a lot of people don't know about neutrino they would think this answer if the 2nd smallest. Although this is the smallest discovered. There is a lot of smaller thing that have not been proved to exist. Like string particles, planck particle. Which if those are real, they are predicted to be MILLIONS of times smaller. Maybe a lot more. I'm sorry but even I don't know a lot of information about neutrino. And it might be hard to find information about it.

This is a difficult question because size doesn't really apply to particle physics, even less when one considers particle-wave dualities. Of all the particles that can be considered as "matter", muon neutrinos (νμ) are currently understood as the lightest, with a mass of about 170 keV, or around 3.311 x 10-31 kilograms.

On the other hand, forces are also carried by (non-matter) particles, photons (mediate the electromagnetic force) and gluons (mediate the strong nuclear force) are both known to have zero mass.
the lepton and quark

Answer 2

atom