BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:HEP Colloquia 2026
DTSTART:20260526T123000Z
DTEND:20260526T133000Z
DTSTAMP:20260715T073800Z
UID:indico-event-52491@agenda.infn.it
CONTACT:hepcolloquia@ca.infn.it
DESCRIPTION:Speakers: Marco Piva\n\nQuantum field theory of gravity from p
 urely virtual particles\nQuadratic gravity offers a compelling path to a r
 enormalizable quantum theory of gravitational interactions. However\, reno
 rmalizability comes at the price of unitarity\, which is violated by the p
 resence of ghosts\, undermining its physical viability. Purely virtual par
 ticles (PVP) provide a solution to this problem. They are novel degrees of
  freedom that can mediate interactions without ever appearing as on-shell 
 states\, allowing quadratic gravity to preserve its ultraviolet behavior w
 hile restoring unitarity.After reviewing the problem of nonrenormalizabili
 ty in Einstein gravity\, I will show the relation between renormalizabilit
 y and unitarity violation in quadratic gravity and explain how PVP can be 
 consistently incorporated into general quantum field theories. Finally\, I
  will discuss potential observable imprints of PVP in inflationary cosmolo
 gy\, as well as in particle physics.\n\nhttps://agenda.infn.it/event/52491
 /
LOCATION:Sala Consiliare (Department of Physics)
URL:https://agenda.infn.it/event/52491/
END:VEVENT
END:VCALENDAR