W bosons are fundamental particles that mediate the weak nuclear force, one of the four fundamental forces of nature. Unlike photons, which are massless and mediate the electromagnetic force, W bosons are massive—weighing around 80 times more than a proton.
There are two types: W⁺ and W⁻, which are electrically charged and responsible for charged current weak interactions. These include processes like:
- Beta decay, where a neutron turns into a proton, an electron, and an antineutrino.
- Neutrino interactions, such as when a neutrino changes a neutron into a proton.
The large mass of the W bosons explains why the weak force is short-ranged and much weaker than electromagnetism at everyday energy scales.
The origin of their mass is explained by the Higgs mechanism, which gives mass to the W and Z bosons while leaving the photon massless. This mass difference is what breaks the electroweak symmetry and separates the weak force from electromagnetism in the low-energy universe we observe today.
In summary, W bosons are key to processes that change particle types (flavors), especially in radioactive decay and nuclear fusion, and their mass is central to the unique behavior of the weak force.