Unified picture ofQ-balls and boson stars via catastrophe theory

We make an analysis of Q-balls and boson stars using catastrophe theory, as an extension of the previous work on Q-balls in flat spacetime. We adopt the potential V₃(φ)=m²2φ²-μφ³+λφ⁴ for Q-balls and that with μ=0 for boson stars. For solutions with |gʳʳ-1|~1 at its peak, stability of Q-balls has been lost regardless of the potential parameters. As a result, phase relations, such as a Q-ball charge versus a total Hamiltonian energy, approach those of boson stars, which gives us a unified picture of Q-balls and boson stars.