TY - JOUR

T1 - The cosmological moduli problem and naturalness

AU - Bae, Kyu Jung

AU - Baer, Howard

AU - Barger, Vernon

AU - Deal, Robert Wiley

N1 - Publisher Copyright:
© 2022, The Author(s).

PY - 2022/2

Y1 - 2022/2

N2 - Nowadays, the cosmological moduli problem (CMP) comes in three parts: 1. potential violation of Big-Bang nucleosynthesis (BBN) constraints from late decaying moduli fields, 2. the moduli-induced gravitino problem wherein gravitinos are overproduced and their decays violate BBN or dark matter overproduction bounds and 3. the moduli-induced lightest SUSY particle (LSP) overproduction problem. Also, the CMP may be regarded as either a problem or else a solution to scenarios with dark matter over- or under-production. We examine the cosmological moduli problem and its connection to electroweak naturalness. We calculate the various two-body decay widths of a light modulus field into MSSM particles and gravitinos within general supersymmetric models. We include both phase space and mixing effects. We examine cases without and with helicity suppression of modulus decays to gravitinos (cases 1 & 2) and/or gauginos (cases A & B). For case B1, we evaluate regions of gravitino mass m3/2 vs. modulus mass mϕ parameter space constrained by BBN, by overproduction of gravitinos and by overproduction of neutralino dark matter, along with connections to naturalness. For this case, essentially all of parameter space is excluded unless mϕ ≳ 2.5 × 103 TeV with mϕ< 2m3/2. For a potentially most propitious case B2 with ϕ decay to Higgs and matter turned off, then modulus branching fractions to SUSY and to gravitinos become highly suppressed at large mϕ. But since the modulus number density increases faster than the branching fractions decrease, there is still gross overproduction of neutralino dark matter. We also show that in this scenario the thermally produced gravitino problem is fixed by huge entropy dilution, but non-thermal gravitino production from moduli decay remains a huge problem unless it is kinematically suppressed with mϕ< 2m3/2. In a pedagogical appendix, we present detailed calculations of modulus field two-body decay widths.

AB - Nowadays, the cosmological moduli problem (CMP) comes in three parts: 1. potential violation of Big-Bang nucleosynthesis (BBN) constraints from late decaying moduli fields, 2. the moduli-induced gravitino problem wherein gravitinos are overproduced and their decays violate BBN or dark matter overproduction bounds and 3. the moduli-induced lightest SUSY particle (LSP) overproduction problem. Also, the CMP may be regarded as either a problem or else a solution to scenarios with dark matter over- or under-production. We examine the cosmological moduli problem and its connection to electroweak naturalness. We calculate the various two-body decay widths of a light modulus field into MSSM particles and gravitinos within general supersymmetric models. We include both phase space and mixing effects. We examine cases without and with helicity suppression of modulus decays to gravitinos (cases 1 & 2) and/or gauginos (cases A & B). For case B1, we evaluate regions of gravitino mass m3/2 vs. modulus mass mϕ parameter space constrained by BBN, by overproduction of gravitinos and by overproduction of neutralino dark matter, along with connections to naturalness. For this case, essentially all of parameter space is excluded unless mϕ ≳ 2.5 × 103 TeV with mϕ< 2m3/2. For a potentially most propitious case B2 with ϕ decay to Higgs and matter turned off, then modulus branching fractions to SUSY and to gravitinos become highly suppressed at large mϕ. But since the modulus number density increases faster than the branching fractions decrease, there is still gross overproduction of neutralino dark matter. We also show that in this scenario the thermally produced gravitino problem is fixed by huge entropy dilution, but non-thermal gravitino production from moduli decay remains a huge problem unless it is kinematically suppressed with mϕ< 2m3/2. In a pedagogical appendix, we present detailed calculations of modulus field two-body decay widths.

KW - Cosmology of Theories BSM

KW - Early Universe Particle Physics

KW - Models for Dark Matter

KW - Supersymmetry

UR - http://www.scopus.com/inward/record.url?scp=85125362809&partnerID=8YFLogxK

U2 - 10.1007/JHEP02(2022)138

DO - 10.1007/JHEP02(2022)138

M3 - Article

AN - SCOPUS:85125362809

SN - 1029-8479

VL - 2022

JO - Journal of High Energy Physics

JF - Journal of High Energy Physics

IS - 2

M1 - 138

ER -