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SUMMARY:Duarte Feiteira (Helsinki U.): Cosmological gravitational particle
  production: Scalars and fermions
DTSTART:20260507T111500Z
DTEND:20260507T123000Z
DTSTAMP:20260523T023900Z
UID:indico-event-9340@indico.fysik.su.se
DESCRIPTION:Title: Cosmological gravitational particle production: Scalars
  and fermions\nAbstract: Particle production in the Early Universe is one 
 of the cornerstones of modern cosmology and plays an important role in dar
 k-matter phenomenology. In this talk\, I will discuss the gravitational pr
 oduction of scalars and fermions during inflation. For scalars\, I will co
 mpare Bogolyubov coefficient and Starobinsky stochastic approaches\, showi
 ng that they only agree in the limit of infinitely long inflation. High-sc
 ale inflation is very efficient in particle production\, leading to constr
 aints on the existence of free\, light\, and stable scalars: such particle
 s are viable only if their masses are below the eV scale or if the reheati
 ng temperature is in the GeV range. For fermions\, I will show how the pro
 duction efficiency depends on the particle mass\, which is generated via t
 he Yukawa coupling and sensitive to the corresponding scalar field value. 
 Scalar fields can experience large quantum fluctuations during inflation\,
  driving the average field to the Hubble scale and above. Thus\, fermions 
 can be very heavy during inflation\, enhancing particle production. This m
 echanism can be the leading source of right-handed neutrinos\, if they gai
 n a Majorana mass from the Yukawa coupling to a singlet scalar.\n \nPlace
 : CoPS room/A5:1041 and Zoom\n\nhttps://indico.fysik.su.se/event/9340/
LOCATION:AlbaNova A5:1041 - CoPS grupprum (AlbaNova Main Building)
URL:https://indico.fysik.su.se/event/9340/
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