Enlarging the space of viable inflation models: A slingshot mechanism

Abstract

The viability of a given model for inflation is determined not only by the form of the inflaton potential, but also by the initial inflaton field configuration. In many models, field configurations which are otherwise well-motivated nevertheless fail to induce inflation, or fail to produce an inflationary epoch of duration sufficient to solve the horizon and flatness problems. In this paper, we propose a mechanism which enables inflation to occur even with such initial conditions. Our mechanism involves multiple scalar fields which experience a time-dependent mixing. This in turn leads to a "re-overdamping" phase as well as a parametric resonance which together "slingshot" the inflaton field from regions of parameter space that do not induce inflation to regions that do. Our mechanism is flexible, dynamical, and capable of yielding an inflationary epoch of sufficiently long duration. This slingshot mechanism can therefore be utilized in a variety of settings and thereby enlarge the space of potentially viable inflation models.

Deciphering the archaeological record: Cosmological imprints of nonminimal dark sectors

“…Alternatively, a time dependence for the ðm 2 l Þ eff can also arise directly as a consequence of dynamical processes which do not involve modulation of the VEVs of other dark-sector fields-e.g., from a cosmological phase transition. Even considering only the effect on the VEVs, multiple fields receiving such dynamical mass contributions exhibit an array of possible behaviors [75][76][77]. Furthermore, when the ðm 2 l Þ eff evolve in this way, the pattern of intra-ensemble decays could be drastically altered, thereby modifying the ultimate shape of the resulting dark-matter phase-space distributions.…”

Deciphering the Archaeological Record: Cosmological Imprints of Non-Minimal Dark Sectors

“…Alternatively, a time-dependence for the (m 2 ) eff can also arise directly as a consequence of dynamical processes which do not involve modulation of the VEVs of other dark-sector fieldse.g., from a cosmological phase tran-sition. Even considering only the effect on the VEVs, multiple fields receiving such dynamical mass contributions exhibit an array of possible behaviors [75][76][77]. Furthermore, when the (m 2 ) eff evolve in this way, the pattern of intra-ensemble decays could be drastically altered, thereby modifying the ultimate shape of the resulting dark-matter phase-space distributions.…”

More is Different: Non-Minimal Dark Sectors and their Implications for Particle Physics, Astrophysics, and Cosmology -- 13 Take-Away Lessons for Snowmass 2021

“…Indeed it is shown in Ref. [30] that this can actually occur quite generically without fine-tuning. Although the field will eventually skid to a halt during the subsequent re-overdamped phase, the field can nevertheless reach huge field values before coming to a halt.…”

“…Moreover, the dark states within different DDM models can accrue suitable cosmological abundances in a variety of ways. These include not only non-thermal generation mechanisms such as misalignment production [2,3] and mass-generating phase transitions in the early Universe [28][29][30], but also thermal mechanisms such as freeze-out [31]. In fact, DDM ensembles satisfying the scaling relations in Eq.…”

“…8 has given rise to two distinct phenomena: the parametric resonance and the entry into a re-overdamped phase. However, under certain circumstances [30] these two features can be combined in order to "slingshot" the field to extremely large values. This behavior is shown in Fig.…”