Quarks are the building blocks of protons and neutrons. Think of a proton as a word made from letters (quarks). There are six types (flavours) of quarks, but only two are common inside nuclei: the up quark (\$u\$) and the down quark (\$d\$). A proton is made of two up quarks and one down quark (\$uud\$), while a neutron is two down quarks and one up quark (\$udd\$).
During β– decay, a neutron turns into a proton. Imagine swapping one letter in the word “neutron” to make “proton.” The change happens at the quark level: a down quark (\$d\$) inside the neutron changes into an up quark (\$u\$). This is like turning a “d” into a “u”. The process also releases an electron (\$e^-\$) and an antineutrino (\$\bar{\nu}_e\$).
| Initial Nucleon | Quark Change | Final Nucleon | Particles Emitted |
|---|---|---|---|
| Neutron (\$udd\$) | \$d \rightarrow u\$ | Proton (\$uud\$) | \$e^- + \bar{\nu}_e\$ |
In β+ decay, a proton turns into a neutron. Think of changing a letter in “proton” to make “neutron.” Here, an up quark (\$u\$) inside the proton changes into a down quark (\$d\$). This emits a positron (\$e^+\$) and a neutrino (\$\nu_e\$).
| Initial Nucleon | Quark Change | Final Nucleon | Particles Emitted |
|---|---|---|---|
| Proton (\$uud\$) | \$u \rightarrow d\$ | Neutron (\$udd\$) | \$e^+ + \nu_e\$ |
Remember: In β– decay a down quark turns into an up quark, producing an electron and an antineutrino. In β+ decay a up quark turns into a down quark, producing a positron and a neutrino.
⚠️ Don’t forget that the \$W\$ boson is very short‑lived and decays almost instantly into the lepton pair.