TY - JOUR

T1 - Banks-Zaks cosmology, inflation, and the Big Bang singularity

AU - Artymowski, Michal

AU - Ben-Dayan, Ido

AU - Kumar, Utkarsh

N1 - Publisher Copyright:
© 2020 IOP Publishing Ltd and Sissa Medialab.

PY - 2020/5

Y1 - 2020/5

N2 - We consider the thermodynamical behavior of Banks-Zaks theory close to the conformal point in a cosmological setting. Due to the anomalous dimension, the resulting pressure and energy density deviate from that of radiation and result in various interesting cosmological scenarios. Specifically, for a given range of parameters one avoids the cosmological singularity. We provide a full "phase diagram" of possible Universe evolution for the given parameters. For a certain range of parameters, the thermal averaged Banks-Zaks theory alone results in an exponentially contracting universe followed by a non-singular bounce and an exponentially expanding universe, i.e. Inflation without a Big Bang singularity, or shortly termed "dS Bounce". The temperature of such a universe is bounded from above and below. The result is a theory violating the classical Null Energy Condition (NEC). Considering the Banks-Zaks theory with an additional perfect fluid, yields an even richer phase diagram that includes the standard Big Bang model, stable single "normal" bounce, dS Bounce and stable cyclic solutions. The bouncing and cyclic solutions are with no singularities, and the violation of the NEC happens only near the bounce. We also provide simple analytical conditions for the existence of these non-singular solutions. Hence, within effective field theory, we have a new alternative non-singular cosmology based on the anomalous dimension of Bank-Zaks theory that may include inflation and without resorting to scalar fields.

AB - We consider the thermodynamical behavior of Banks-Zaks theory close to the conformal point in a cosmological setting. Due to the anomalous dimension, the resulting pressure and energy density deviate from that of radiation and result in various interesting cosmological scenarios. Specifically, for a given range of parameters one avoids the cosmological singularity. We provide a full "phase diagram" of possible Universe evolution for the given parameters. For a certain range of parameters, the thermal averaged Banks-Zaks theory alone results in an exponentially contracting universe followed by a non-singular bounce and an exponentially expanding universe, i.e. Inflation without a Big Bang singularity, or shortly termed "dS Bounce". The temperature of such a universe is bounded from above and below. The result is a theory violating the classical Null Energy Condition (NEC). Considering the Banks-Zaks theory with an additional perfect fluid, yields an even richer phase diagram that includes the standard Big Bang model, stable single "normal" bounce, dS Bounce and stable cyclic solutions. The bouncing and cyclic solutions are with no singularities, and the violation of the NEC happens only near the bounce. We also provide simple analytical conditions for the existence of these non-singular solutions. Hence, within effective field theory, we have a new alternative non-singular cosmology based on the anomalous dimension of Bank-Zaks theory that may include inflation and without resorting to scalar fields.

KW - cosmic singularity

KW - particle physics - cosmology connection

KW - physics of the early universe

UR - http://www.scopus.com/inward/record.url?scp=85085706218&partnerID=8YFLogxK

U2 - 10.1088/1475-7516/2020/05/015

DO - 10.1088/1475-7516/2020/05/015

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AN - SCOPUS:85085706218

SN - 1475-7516

VL - 2020

JO - Journal of Cosmology and Astroparticle Physics

JF - Journal of Cosmology and Astroparticle Physics

IS - 5

M1 - 015

ER -