Resonant annihilation of long-lived massive colored particles through hadronic collisions

Abstract

Hypothetical long-lived massive colored particles (MCPs or $Y\mathrm{s}$) would be confined in colorless exotic strongly interacting massive particles (SIMPs) at a color confinement temperature of ${T}_{\mathrm{C}}\ensuremath{\sim}200\text{ }\text{ }\mathrm{MeV}$. Two long-lived MCPs form a bound state ($Y\overline{Y}$) at collisions of two SIMPs. We study sensitivities of MCP annihilation to decay properties of resonances ($Y\overline{Y}$), and binding energies or energy levels of exotic SIMPs. The ($Y\overline{Y}$) formation is assumed to dominantly proceed through resonances of ($Y\overline{Y}$) in this paper. We make a toy model of the effective cross section for $Y\overline{Y}$ annihilation. Abundances of SIMPs are then calculated for different sets of parameters specifying properties of ($Y\overline{Y}$) resonances, binding energies of SIMPs, the initial abundance and the mass of MCP. Calculated relic abundances for respective SIMP species are $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}--3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ times that of baryon. They can be much higher but cannot be much smaller than the previous estimate. The abundances can be consistent depending on parameters with the possible scenario that SIMPs bind to nuclei and subsequent exotic nuclear reactions reduce the primordial abundance of $^{7}\mathrm{Li}$ or enhance those of $^{9}\mathrm{Be}$ and/or B in the early Universe. A unique information on the quark-hadron phase transition in the early Universe may become available in future by elaborated studies on the annihilation process with light element abundances as observables.