TY - JOUR

T1 - Measuring inflaton couplings via dark radiation as Δneff in CMB

AU - Ghoshal, Anish

AU - Lalak, Zygmunt

AU - Porey, Shiladitya

N1 - Work of Shiladitya Porey is funded by RSF Grant No. 19-42-02004.

PY - 2023/9/15

Y1 - 2023/9/15

N2 - We study the production of a beyond the Standard Model (BSM) free-streaming relativistic particles which contribute to Neff and investigate how much the predictions for the inflationary analysis change. We consider inflaton decay as the source of this dark radiation (DR) and use the cosmic microwave background (CMB) data from Planck-2018 to constrain the scenarios and identify the parameter space involving couplings and masses of the inflaton that will be within the reach of next-generation CMB experiments like spt-3g, CMB-S4, CMB-Bhārat, PICO, CMB-HD, etc. We find that if the BSM particle is produced only from the interaction with inflaton along with Standard Model (SM) relativistic particles, then its contribution to Neff is a monotonically increasing function of the branching fraction, BX of the inflaton to the BSM particle X; Planck bound on Neff rules out such BX≳0.09. Considering two different analyses of Planck+bicep data together with other cosmological observations, Neff is treated as a free parameter, which relaxes the constraints on scalar spectral index (ns) and tensor-to-scalar ratio (r). The first analysis leads to predictions on the inflationary models like hilltop inflation being consistent with the data. Second analysis rules out the possibility that BSM particle X producing from the inflaton decay in Coleman-Weinberg inflation or Starobinsky inflation scenarios. To this end, we assume that SM Higgs is produced along with the BSM particle. We explore the possibilities that X can be either a scalar or a fermion or a gauge boson and consider possible interactions with inflaton and find out the permissible range on the allowed parameter space Planck and those which will be within the reaches of future CMB observations.

AB - We study the production of a beyond the Standard Model (BSM) free-streaming relativistic particles which contribute to Neff and investigate how much the predictions for the inflationary analysis change. We consider inflaton decay as the source of this dark radiation (DR) and use the cosmic microwave background (CMB) data from Planck-2018 to constrain the scenarios and identify the parameter space involving couplings and masses of the inflaton that will be within the reach of next-generation CMB experiments like spt-3g, CMB-S4, CMB-Bhārat, PICO, CMB-HD, etc. We find that if the BSM particle is produced only from the interaction with inflaton along with Standard Model (SM) relativistic particles, then its contribution to Neff is a monotonically increasing function of the branching fraction, BX of the inflaton to the BSM particle X; Planck bound on Neff rules out such BX≳0.09. Considering two different analyses of Planck+bicep data together with other cosmological observations, Neff is treated as a free parameter, which relaxes the constraints on scalar spectral index (ns) and tensor-to-scalar ratio (r). The first analysis leads to predictions on the inflationary models like hilltop inflation being consistent with the data. Second analysis rules out the possibility that BSM particle X producing from the inflaton decay in Coleman-Weinberg inflation or Starobinsky inflation scenarios. To this end, we assume that SM Higgs is produced along with the BSM particle. We explore the possibilities that X can be either a scalar or a fermion or a gauge boson and consider possible interactions with inflaton and find out the permissible range on the allowed parameter space Planck and those which will be within the reaches of future CMB observations.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85172806109&origin=inward&txGid=54fdeefcba951c261f0871eaf0c5dcef

UR - https://www.mendeley.com/catalogue/5ccb61cf-fb09-370c-8cf6-357288b64642/

U2 - 10.1103/PhysRevD.108.063030

DO - 10.1103/PhysRevD.108.063030

M3 - Article

VL - 108

JO - Physical Review D

JF - Physical Review D

SN - 2470-0010

IS - 6

M1 - 063030

ER -