Phase-Induced Particle Creation in the Kappa-Gamma Vacuum

We introduce a two-parameter ($κ, γ$) family of field modes in flat spacetime that generalizes the recently developed $κ$-plane wave modes, which correspond to real squeezing. By incorporating a phase parameter, $γ$, our new kappa gamma plane wave modes describe a vacuum state, $| 0_{κ,γ} \rangle$, characterized by continuous-mode phase squeezing, where $κ$ governs the squeezing magnitude and $γ$ sets its angle. This generalization reveals a novel physical effect: particle creation induced purely by a relative phase shift between observers. The particle spectrum is shown to be a function of this phase difference and the deformation parameter $κ$. This work provides a comprehensive framework for exploring a new class of non-trivial quantum vacua, where both thermal and squeezing properties can be continuously adjusted.