A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Particle decay in expanding Friedmann-Robertson-Walker universes
Tekijät: Juho Lankinen, Iiro Vilja
Kustantaja: AMER PHYSICAL SOC
Julkaisuvuosi: 2018
Journal: Physical Review D
Tietokannassa oleva lehden nimi: PHYSICAL REVIEW D
Lehden akronyymi: PHYS REV D
Artikkelin numero: ARTN 045010
Vuosikerta: 98
Numero: 4
Sivujen määrä: 9
ISSN: 2470-0010
DOI: https://doi.org/10.1103/PhysRevD.98.045010
Tiivistelmä
The lack of energy conservation introduces new particle processes in curved spacetime that are forbidden in flat space. Therefore, one has to be very cautious about using the results calculated in Minkowskian space in early Universe applications. This is true for particle decay rates in particular, which need to be calculated using quantum field theory in curved spacetime. Previous studies are usually restricted to using minimal or conformal coupling for the decaying particle, while using a more general coupling would give deeper insight into particle decay. This paper presents the results we obtained for a massive particle decaying in a general power-law universe with arbitrary coupling to gravity. We find that, depending on the value of the gravitational coupling, the effect of gravitation may either strengthen or weaken the decay. The analysis further reveals that, apart from radiation-dominated universe, there are values of the coupling constant for which the decay rate is exactly Minkowskian for all universe types. Because the decay rate may be considerably modified in curved space, these issues need to be considered when doing precise cosmological calculations.
The lack of energy conservation introduces new particle processes in curved spacetime that are forbidden in flat space. Therefore, one has to be very cautious about using the results calculated in Minkowskian space in early Universe applications. This is true for particle decay rates in particular, which need to be calculated using quantum field theory in curved spacetime. Previous studies are usually restricted to using minimal or conformal coupling for the decaying particle, while using a more general coupling would give deeper insight into particle decay. This paper presents the results we obtained for a massive particle decaying in a general power-law universe with arbitrary coupling to gravity. We find that, depending on the value of the gravitational coupling, the effect of gravitation may either strengthen or weaken the decay. The analysis further reveals that, apart from radiation-dominated universe, there are values of the coupling constant for which the decay rate is exactly Minkowskian for all universe types. Because the decay rate may be considerably modified in curved space, these issues need to be considered when doing precise cosmological calculations.
Turun yliopiston Tutkimustietojärjestelmän portaali