How many hypothetical particles do we need

[wolram]

How many as yet undiscovered particles do we need to make the standard model work?

 

[Orodruin]

Define "work".

 

[Space Dragon]

Physicists have developed a theory called The standard model to explain how particles holds the universe together.
The standard model basically includes 6 leptons,6 quarks,Force carrier particles.
The quarks are classified as up,down,top,bottom,charm,strange.
The leptons are classified as electron,muon,tau,electron neutrino,muon neutrino,tau neutrino.
The force carriers include photons,gluons,W boson,Z boson.

 

[wolram]

Define "work".

The graviton is needed for our theories of gravity
Some as yet unknown particle is needed to make dark matter work.
etc.

graviton https://en.wikipedia.org/wiki/Graviton
Axion https://en.wikipedia.org/wiki/Axion
etc.

 

[wolram]

WIMPs and MACHOs http://www.astro.caltech.edu/~george/ay21/eaa/eaa-wimps-machos.pdf

 

[Orodruin]

The graviton is needed for our theories of gravity
Some as yet unknown particle is needed to make dark matter work.
etc.

graviton https://en.wikipedia.org/wiki/Graviton
Axion https://en.wikipedia.org/wiki/Axion
etc.

But the standard model does not deal with gravity, nor does it deal with a solution to the dark matter problem. Since the are open problems, we have no idea what is required.

Also, current gravitational theories do not require a graviton. Quantisations of them do.