[katieHaylor (OP)]

Paul says:

I've recently read in the New Scientist that previously undetected dark matter has been discovered, in the form of baryon particles. What are baryon particles, and who first discovered them?

Can you help?

[evan_au]

previously undetected dark matter has been discovered

I think that you will find that what was discovered in this article was "normal" (baryonic) matter.

Continue this part of the discussion in this prior thread: https://www.thenakedscientists.com/forum/index.php?topic=71582.0

What are baryon particles

Baryon particles include the proton and neutron, which make up the nucleus of atoms (and over 99.9% of the mass of the atom).

Today, we define baryons as particles made up of 3 quarks.

The name "baryon" means "heavy", because they were heavier than other subatomic particles that were known at the time (eg electrons, which are called "leptons", because they are lightweights by comparison).
See: https://en.wikipedia.org/wiki/Baryon

...and who first discovered them?

Rutherford named the proton in 1920, and Chadwick detected neutrons in 1932.

See: https://en.wikipedia.org/wiki/Discovery_of_the_neutron

[jeffreyH]

Leptons and baryons are in a class of particles called fermions. This is distinct from the class of particles known as bosons. The fermions have fractional spin, whereas bosons have integer spin.
https://en.m.wikipedia.org/wiki/List_of_particles