During a beta decay of a free neutron, the electron's origin can be traced to the transformation of one of the neutron's down quarks into an up quark. This process is mediated by the weak nuclear force. Here's a step-by-step explanation:
- A free neutron, composed of two down quarks and one up quark (udd), undergoes beta decay.
- One of the down quarks in the neutron transforms into an up quark through the weak nuclear force, resulting in the conversion of a down quark to an up quark.
- In this process, a W- boson is emitted from the decaying down quark. The W- boson carries away the excess negative charge and the difference in flavor between the initial and final quarks.
- The W- boson quickly decays into an electron (e-) and an electron antineutrino (ν̅e). The electron is negatively charged, and the electron antineutrino is an electrically neutral, very light particle.
This process allows for the conservation of various properties, such as electric charge and lepton number. The total charge of the neutron, which is zero, is conserved in the process as the negative charge of the electron balances out the positive charge of the up quark.
As for how we know this process is real, it is based on experimental observations and theoretical understanding. Beta decay has been studied extensively in laboratory experiments, and its properties, including the emission of an electron and electron antineutrino, have been well-documented.
Additionally, the theoretical framework of the Standard Model of particle physics provides a comprehensive description of the fundamental particles and their interactions, including the weak nuclear force responsible for beta decay. The Standard Model has been tested and validated by numerous experiments, further confirming the reality of the electron's origin in beta decay.
In summary, the electron's origin in beta decay can be explained through the transformation of a down quark into an up quark, mediated by the weak nuclear force. Experimental observations and the theoretical framework of the Standard Model support the reality of this process.