In the mathematical framework of quantum mechanics, specifically quantum field theory (QFT), probabilities are typically described by amplitudes, which are complex numbers. These amplitudes are combined using mathematical operations to calculate the probabilities of various outcomes in quantum processes.
In quantum mechanics, the concept of infinitesimal probabilities or probabilities going completely down to zero does not arise. Instead, probabilities are represented by non-zero values. However, there are situations where the probability of a particular outcome can be extremely small or close to zero.
For example, in certain quantum processes, the probability of an event occurring may be suppressed by interference effects. This means that the probability amplitude for that event is significantly smaller compared to other possibilities, leading to a very small probability for that specific outcome. This phenomenon is often referred to as "quantum suppression" or "quantum suppression of probabilities."
It is important to note that even though the probability may be extremely small, it is not zero. In the mathematical formalism of quantum mechanics, probabilities are calculated as the square of the absolute value of the probability amplitudes. As long as the probability amplitude is non-zero, no matter how small, there remains a finite probability associated with the outcome.
It is worth mentioning that quantum field theory allows for the consideration of processes involving virtual particles, which have different properties from observable particles. These virtual particles can contribute to intermediate steps in calculations, and their effects can be taken into account using perturbative techniques. In certain calculations, terms involving virtual particles may be small, but they are not truly zero.
Overall, in the mathematical model of quantum field theory, probabilities are finite non-zero quantities, although they can sometimes be extremely small or suppressed due to various factors such as interference effects.