📝 SummarXiv

Abstract

The past decades witnessed the golden era of hadron physics, which gives us a good opportunity to study the physics happening in a transient period of time. The development on the singly heavy baryons indicates that there exists the fine structure of hadron spectrum caused by the direct strong interaction, and the development on the exotic hadrons indicates that the residue strong interaction is capable of forming the hadronic molecules. Similar to the electromagnetic interaction, the strong interaction may be capable of forming some imaginable hadronic worlds. Moreover, there can be various worlds formed by various fundamental physical laws. Some hadrons have so transient lifetimes that they may not even be formed. We discuss whether these non-existent particles are capable of affecting our realistic world. We discuss what kinds of particles exist, and so can be observed, in our realistic world. We conjecture that the ratios $R \equiv M/\Gamma \gg 1/2$ ($M \tau \gg \hbar/2$) and $R \equiv M/\Gamma < 1/2$ ($M \tau < \hbar/2$) can be used to describe the particles existing and not-existing in our realistic world, respectively. Here $M$, $\Gamma$, and $\tau$ are the mass, width, and lifetime, respectively. We propose to use the ratio $R \equiv M/\Gamma \sim 1/2$ ($M \tau \sim \hbar/2$) to describe the particles quasi-existing in our realistic world, whose studies may allow us to go beyond the quantum physics and arrive at another type of boundary of our realistic world, that is from the existent to the non-existent. We propose to investigate the quasi-existent particles by studying the singly heavy baryons through various imperfect symmetries among them. We obtain an incidental conjecture that the lifetime and width may be quantized for the particles existing in our realistic world as \begin{equation*}M\tau=n\hbar/2~~~{\rm{and}}~~~M/\Gamma=n/2\,,~~~n=1,2,3\cdots\,.\end{equation*}