The concepts of "strangeness" and "bottomness" are associated with specific quarks and are defined based on their quantum numbers. The strange quark (s) and the bottom quark (b) are two of the six flavors of quarks in the Standard Model of particle physics.
Strangeness (S) and bottomness (B) are quantum numbers that were introduced to explain certain observed properties of particles containing strange and bottom quarks, respectively. These quantum numbers help characterize the behavior and interactions of these particles.
The convention of assigning a negative value to the strangeness and bottomness quantum numbers arises from historical reasons and the way they were originally defined. It was noticed that strange particles (containing strange quarks) tended to have a longer lifetime compared to non-strange particles, and they were often produced in high-energy collisions and then decayed weakly over time.
In order to explain the conservation of certain quantities during weak interactions, such as the conservation of strangeness, the concept of "strangeness number" was introduced. The strangeness quantum number (S) was defined to be +1 for strange quarks, -1 for strange antiquarks, and 0 for all other particles.
Similarly, the concept of "bottomness number" (B) was introduced to describe particles containing bottom quarks. The bottomness quantum number is +1 for bottom quarks, -1 for bottom antiquarks, and 0 for other particles.
The convention of assigning negative values to these quantum numbers is simply a matter of convention and mathematical convenience. It helps in maintaining the consistency of certain conservation laws and simplifies the mathematical formulations in particle physics.