Effective reheating in Gauss–Bonnet inflation with μ (ϕ ,X) coupling
- 1University of Mazandaran
Abstract
We study effective reheating in a scalar–Gauss–Bonnet inflationary model with a phase-space-dependent coupling μ (ϕ ,X), in which a compact field-space feature is combined with a bounded kinetic gate. The modified inflationary background determines the pivot-scale quantities and the effective energy density at the end of inflation. These quantities are then used to derive the reheating duration Nre and temperature Tre through the thermal-history matching relation. We first perform two fixed-pivot reference scans by varying the overall Gauss–Bonnet strength λ GB and the kinetic-gate amplitude gX separately. For the reference parameter choices, increasing either parameter increases Nre and decreases Tre for the selected reheating equations of state. Additional benchmark calculations clarify how these variations depend on the dynamical regime of the model. In the λ GB scan, the increase in Nre and the decrease in Tre persist, although both variations become strongly suppressed when the coupling is more localized or when the end of inflation is controlled more strongly by the E-model potential. In the gX scan, stronger field-space localization and kinetic saturation can instead lead to a slight decrease in Nre and an increase in Tre as gX is increased. When the bounded kinetic contribution is considered together with a weaker overall Gauss–Bonnet interaction, the resulting changes in the reheating quantities become nearly negligible. The fixed-pivot predictions of the representative and alternative benchmarks are compared with CMB constraints. These reheating constraints are then discussed for four representative values of the effective equation-of-state parameter, w̅re=−1/3,0,2/3, and 1. Finally, the analysis is generalized to a time-dependent reheating equation of state wre(N), showing that the thermal-history matching relations depend only on its e-fold average w̅re, while the detailed evolution of wre(N) remains degenerate within the effective framework adopted here.
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BibTeX
@article{seidabadi2026effective,
title = {{Effective reheating in Gauss–Bonnet inflation with $$\mu (\phi ,X)$$ coupling}},
author = {Ali Seidabadi and Sara Saghafi and Kourosh Nozari},
journal = {The European Physical Journal C},
year = {2026},
month = nov,
doi = {10.1140/epjc/s10052-026-16525-y},
url = {https://link.springer.com/article/10.1140/epjc/s10052-026-16525-y},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Effective reheating in Gauss–Bonnet inflation with μ (ϕ ,X) coupling
AU - Ali Seidabadi
AU - Sara Saghafi
AU - Kourosh Nozari
PY - 2026
DA - 2026/11/06
JO - The European Physical Journal C
DO - 10.1140/epjc/s10052-026-16525-y
UR - https://link.springer.com/article/10.1140/epjc/s10052-026-16525-y
AB - We study effective reheating in a scalar–Gauss–Bonnet inflationary model with a phase-space-dependent coupling μ (ϕ ,X), in which a compact field-space feature is combined with a bounded kinetic gate. The modified inflationary background determines the pivot-scale quantities and the effective energy density at the end of inflation. These quantities are then used to derive the reheating duration N_re and temperature T_re through the thermal-history matching relation. We first perform two fixed-pivot reference scans by varying the overall Gauss–Bonnet strength λ _GB and the kinetic-gate amplitude g__X separately. For the reference parameter choices, increasing either parameter increases N_re and decreases T_re for the selected reheating equations of state. Additional benchmark calculations clarify how these variations depend on the dynamical regime of the model. In the λ _GB scan, the increase in N_re and the decrease in T_re persist, although both variations become strongly suppressed when the coupling is more localized or when the end of inflation is controlled more strongly by the E-model potential. In the g__X scan, stronger field-space localization and kinetic saturation can instead lead to a slight decrease in N_re and an increase in T_re as g__X is increased. When the bounded kinetic contribution is considered together with a weaker overall Gauss–Bonnet interaction, the resulting changes in the reheating quantities become nearly negligible. The fixed-pivot predictions of the representative and alternative benchmarks are compared with CMB constraints. These reheating constraints are then discussed for four representative values of the effective equation-of-state parameter, w̅_re=−1/3,0,2/3, and 1. Finally, the analysis is generalized to a time-dependent reheating equation of state w_re(N), showing that the thermal-history matching relations depend only on its e-fold average w̅_re, while the detailed evolution of w_re(N) remains degenerate within the effective framework adopted here.
SN - 1434-6052
ER -