Contents

# Contents

## Idea

A proton is a certain bound state of three quarks, hence a baryon.

The bound states of protons and neutrons (jointly: nucleons) in turn are nuclei, the cores of atoms. The proton alone is the nucleus of the hydrogen atom.

In the standard model of particle physics the proton is stable, and experiment highly constrains possible rare proton decay (see there). But some models beyond the standard model (notably many, but not all, GUT models) do imply rare proton decay.

## Properties

### Mass

A proton has rest mass about a GeV:

$m_{proton} \simeq 0.938 GeV \,.$

### Spin

The contribution of the constituents (quarks, gluons) to the total spin of the proton turns out to be subtle (“proton spin crisis”) Thomas 08.

field (physics)

standard model of particle physics

force field gauge bosons

scalar bosons

flavors of fundamental fermions in the
standard model of particle physics
generation of fermions1st generation2nd generation3d generation
quarks
up-typeup quarkcharm quarktop quark
down-typedown quarkstrange quarkbottom quark
leptons
chargedelectronmuontauon
neutralelectron neutrinomuon neutrinotau neutrino

hadron (bound states of the above quarks)

solitons

minimally extended supersymmetric standard model

superpartners

bosinos:

dark matter candidates

Exotica

auxiliary fields