If matter were composed of top and bottom quarks, it would be significantly different from the matter we encounter in everyday life. Let's consider some properties of such matter:
Mass: Both the top and bottom quarks are much more massive than other quarks. The top quark is the heaviest known elementary particle, with a mass around 173 times that of a proton, while the bottom quark is also relatively heavy. Consequently, matter composed of top and bottom quarks would be incredibly dense.
Stability: Top quarks are extremely short-lived and decay quickly due to their high mass. They have a mean lifetime of approximately 5 x 10^(-25) seconds, which is orders of magnitude shorter than the timescales we typically encounter. Bottom quarks have a longer lifetime but still decay relatively quickly. Therefore, matter composed solely of top and bottom quarks would be highly unstable.
Strong Interaction: Quarks interact via the strong nuclear force, which binds them together inside hadrons (particles like protons and neutrons). Top and bottom quarks would interact with each other through the strong force, resulting in the formation of bound states known as mesons and baryons. These exotic particles would have unique properties due to the heavy mass of the quarks involved.
Electric Charge: Top quarks carry a charge of +2/3, while bottom quarks carry a charge of -1/3. If matter were solely composed of these quarks, it would carry a net electric charge depending on the combination of quarks present.
Quantum Chromodynamics (QCD): The strong interaction between top and bottom quarks would be described by the theory of QCD, which governs the behavior of quarks and gluons. QCD is a highly complex and non-perturbative theory, making the properties and behavior of matter composed solely of top and bottom quarks challenging to calculate precisely.
It's important to note that in the context of the known universe, matter primarily consists of up and down quarks, as well as electrons, which form protons and neutrons, which in turn build atomic nuclei. Quarks like the top and bottom are typically found in high-energy environments, such as particle colliders or in the core of extremely dense astronomical objects like neutron stars.