Upper limits on the Peccei–Quinn scale and on the reheating temperature in axino dark matter scenarios

Abstract

Considering axino cold dark matter scenarios with a long-lived charged slepton, we study constraints on the Peccei-Quinn scale fa and on the reheating temperature TR imposed by the dark matter density and by big bang nucleosynthesis (BBN). For an axino mass compatible with largescale structure, m e a 100 keV, temperatures above 10 9 GeV become viable for fa > 3 × 10 12 GeV. We calculate the slepton lifetime in hadronic axion models. With the dominant decay mode being two-loop suppressed, this lifetime can be sufficiently large to allow for primordial bound states leading to catalyzed BBN of lithium-6 and beryllium-9. This implies new upper limits on fa and on TR that depend on quantities which will be probed at the Large Hadron Collider.PACS numbers: 98.80. Cq, 95.35.+d, 12.60.Jv, 95.30.Cq

Axino cold dark matter revisited

“…[2][3][4] and collider signatures in refs. [8][9][10][17][18][19]. If the LHC does not confirm the decay of heavy squarks or gluino to a lighter neutralino, the axino CDM idea with the R-parity conservation can not be saved unless some other mechanisms such as an effective SUSY is introduced [40,41].…”

“…(2.27), 8) where the upper row relates to the up-type quarks and the lower row to the down-type quarks. These tree-level couplings are always smaller than the one-loop ones for the light generations, but not for the third one.…”

“…[4] and more recently re-derived in ref. [8][9][10] in a full two-loop computation. This coupling is smaller and not important for thermal production, but it is important for the non-thermal production when the stau is the NLSP.…”

“…[1,2]. The scenario was subsequently extensively studied during the last decade [3][4][5][6][7][8][9][10][11][12][13][14][15][16], with either a neutralino or a stau as the next-to-lightest supersymmetric particle (NLSP). Ways of testing the axino CDM scenario at the LHC were explored in refs.…”

“…Ways of testing the axino CDM scenario at the LHC were explored in refs. [8][9][10][17][18][19] and implications for Affleck-Dine Baryogenesis in ref. [20].…”