5.4. MECHANISMS OF SUBATOMIC DECAYS AND ELECTRON RADIATIONS 303
3.Energy conservation.Energy conservation is a universal physical law for all particle
systems. Hence, the energy conservation has also to be satisfied by the weakton exchanges.
This law is manifested in the following prohibitions for decays:
(5.4.11)
e− 9 μ−+νμ+νe,
e− 9 τ−+ντ+νe,
μ− 9 τ−+ντ+νμ.The complete reaction formulas for (5.4.11) are
(5.4.12)
νew 1 w 2 +νμνμ→νμw 1 w 2 +νμ+νe,
νew 1 w 2 +ντντ→ντw 1 w 2 +ντ+νe,
νμw 1 w 2 +ντντ→ντw 1 w 2 +ντ+νμ.From the viewpoints of quantum rules given by (5.3.42) and weakton number conservation,
the decays in (5.4.12) are allowed. However, due to the mass relations
me<mμ<mτ,these weakton exchange processes (5.4.12) violate the energy conservation. Therefore these
decays cannot occur. However, ifν-mediators have high energy to hit electrons, then the
reactions (5.4.12) may occur.
In a weakton exchange process, the energy conservation law can be explicitly expressed
as follows:
Energy Rule 5.13.The composite particles with the lower masses cannot undergo weakton
exchanges with massless mediators in lower energy to decay into the composite particles with
higher masses.
We remark that the Energy Rule5.13is sharper than the energy conservation law. In
fact, the reaction formulas from lower masses to higher masses do not imply that the energy
conservation must be violated. Hence, it is possible that there exist more basic unknown
physical laws under the Energy Rule5.13.
4.Other conservative quantum numbers.From the invariance of weakton numbers, we
deduce immediately the following conserved quantum numbers:
electric chargeQe, weak chargeQw, strong chargeQs,
baryon numberB, lepton numbersLe,Lμ,Lτ.5.4.3 Decay types
In particle physics, the reactions listed in Section5.1.3are classified into two types: the weak
interacting type and the strong interacting type. However,there are no clear definitions to
distinguish them. Usual methods are by experiments to determine reacting intensity, i.e. the
transition probability. In general, the classification is derived based on
weak type: i) presence of leptons in the reactions,
ii) change of strange numbers,
strong type: otherwise.