IPM Calendar 
Wednesday 30 November 2022   Today  
Events for day: Wednesday 16 November 2022    
           13:30 - 15:00     Weekly Seminar (Online)
Ghosts without Runaway



I will discuss our recent work Phys.Rev.Lett. 128 (2022) 4, 041301 in which we present a simple class of mechanical models where a canonical degree of freedom interacts with another one with a negative kinetic term,i.e., with a ghost. We prove analytically that the classical motion of the system is completely stable for all initial conditions, notwithstanding that the conserved Hamiltonian is unbounded from below and above.
Numerical computations fully supported this. Systems with negative kinetic terms often appear in modern cosmology, quantum gravity, and high energy physics and are usually deemed as unstable.
Our result demon ...