BEGIN:VCALENDAR
VERSION:2.0
PRODID:researchseminars.org
CALSCALE:GREGORIAN
X-WR-CALNAME:researchseminars.org
BEGIN:VEVENT
SUMMARY:Alberto Salvio (U. Rome and INFN)
DTSTART:20200521T133000Z
DTEND:20200521T143000Z
DTSTAMP:20260423T035744Z
UID:CENTRA/1
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/CENTRA/1/">I
 nflation and Ultracompact Objects in Quadratic Gravity</a>\nby Alberto Sal
 vio (U. Rome and INFN) as part of CENTRA Seminar\n\n\nAbstract\nAn extensi
 on of general relativity obtained by adding quadratic terms to the action 
 will be considered. Such theory is a UV completion of GR: the additional t
 erms soften gravity above a certain scale and render gravity renormalizabl
 e. The presence of 4 derivatives implies via the Ostrogradsky theorem that
  the classical Hamiltonian is unbounded from below. Nevertheless\, I will 
 argue that the relevant solutions are not unstable\, but metastable: when 
 the energies are much below a threshold (that is high enough to describe t
 he whole cosmology) runaways are avoided. Remarkably\, the chaotic inflati
 on theory of initial conditions ensures that such bound is satisfied and t
 estable implications for the early universe will be discussed. I will also
  argue that the basic unitarity condition is satisfied. Moreover\, thanks 
 to the UV softening of gravity in this theory\, sufficiently light objects
  must be horizonless and explicit analytic examples of horizonless ultraco
 mpact objects (UCOs) will be discussed. These UCOs are more compact than S
 chwarzschild black holes and their spacetime is regular everywhere. Due to
  the lack of a horizon\, light UCOs do not evaporate and\, therefore\, the
 y may play the role of dark matter.\n
LOCATION:https://researchseminars.org/talk/CENTRA/1/
END:VEVENT
END:VCALENDAR