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VERSION:2.0
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SUMMARY:Living with ghosts: stable edition
DTSTART:20231019T143000Z
DTEND:20231019T160000Z
DTSTAMP:20260621T143708Z
UID:51aefbfe-f517-448a-a36a-ad67a4d8e996
SEQUENCE:1
CREATED:20231013T130537Z
DESCRIPTION:ABSTRACT: I will discuss our recent works Phys.Rev.Lett. 128 (
 2022) 4\, 041301 and ePrint: 2305.09631. There we presented a large class 
 of mechanical models where a canonical degree of freedom interacts with an
 other one with a negative kinetic term\, i.e.\, with a ghost and yet the s
 ystem is totally stable. We proved analytically that the classical motion 
 of the system is finite i.e. Lagrange stable for all initial conditions\, 
 notwithstanding that the conserved Hamiltonian is unbounded from below and
  above. Moreover\, there are Lyapunov stable equilibrium configurations. N
 umerical 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 demonstrates that\
 , for mechanical systems\, this common lore can be too naïve and that a s
 table living with ghosts is possible.  
LAST-MODIFIED:20231013T130537Z
LOCATION:Sala de Seminários do DF\,  Pavilhão de Física\, 2º piso
URL:http://df.vps.tecnico.ulisboa.pt/pt/eventos/living-with-ghosts-stable-
 edition/
X-ALT-DESC;FMTTYPE=text/html:<p data-block-key="r6lt0">ABSTRACT: I will di
 scuss our recent works Phys.Rev.Lett. 128 (2022) 4\, 041301 and ePrint: 23
 05.09631. There we presented a large class of mechanical models where a ca
 nonical degree of freedom interacts with another one with a negative kinet
 ic term\, i.e.\, with a ghost and yet the system is totally stable.<br/><b
 r/> We proved analytically that the classical motion of the system is fini
 te i.e. Lagrange stable for all initial conditions\, notwithstanding that 
 the conserved Hamiltonian is unbounded from below and above. Moreover\, th
 ere are Lyapunov stable equilibrium configurations. Numerical computations
  fully supported this. <br/><br/>Systems with negative kinetic terms often
  appear in modern cosmology\, quantum gravity\, and high energy physics an
 d are usually deemed as unstable. Our result demonstrates that\, for mecha
 nical systems\, this common lore can be too naïve and that a stable livin
 g with ghosts is possible.  </p>
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