Mixed Axion/Higgsino Dark Matter Eung Jin Chun Introduction Two “natural” DM candidates predicted by “naturalness” argument: Strong CP problem PQ symmetry scalar DM: Axion Hierarchy problem Supersymmetry fermion DM: Neutralino Higgsino vs. gaugino – supersymmetric vs. SUSY breaking mass: No SUSY yet at LHC – high SUSY breaking masses Light Higgsino – motivated to minimize fine-tuning Higgsino DM lighter than 1 TeV is under-abundant and the rest can come from axion. 2 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Strong CP problem & axion QCD µ parameter allowed in SM strongly constrained by EDM: Weak CP ~ 1 vs. Strong CP <10-11 ?? Peccei-Quinn mechanism: a spontaneously broken QCD-anomalous global U(1) symmetry axion. 9-10 Star cooling Fa > 10 GeV. 3 "Mixed Axion/Higgsino DM" EJChun@KIAS 2015-03-16 Axion DM QCD 휃 term becomes dynamical by a pseudo-Goldstone boson of PQ symmetry: 푎 푔2 푎 푠 ෨ 2 2 ℒ = 2 퐺퐺 → 푚휋푓휋 1 − cos 퐹푎 32휋 퐹푎 Axion oscillation forms cold dark matter: 7 F 6 Λ Ω ℎ2 ≈ 0.18 휃ҧ2 a 푄퐶퐷 푎 1 1012퐺푒푉 400 푀푒푉 Amount of axion DM controlled by 퐹푎 & 휃1ҧ ∈ (0,2휋). 4 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Supersymmetric axion models Two ways to realize PQ symmetry (QCD-anomaly). KSVZ – introduce extra heavy vector-like quarks: 1 0 -1 DFSZ – extend the Higgs bilinear term: 1 -1 -1 0 1 -1 0 1 -1 0 1 -1 “Simultaneous resolution of the strong CP and ¹ problems” Kim-Nilles, ‘84 5 "Mixed Axion/Higgsino DM" EJChun@KIAS 2015-03-16 Light Higgsino for naturalness EWSB in SUSY: Minimization conditions: Natural EWSB: 휇~푀푍 (ex) Radiative realization Baer, et.al., 2012 6 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Higgsino DM abundance Standard thermal freeze-out density (at 푥푓 ≡ 휇/푇푓 ≈ 25): under-abundant for 휇 < 1 푇푒푉 : 휇 2 Ω ℎ2 ≈ 0.1 퐻෩ 1푇푒푉 If over-dumped at 푇퐷 < 푇푓 (푥퐷 > 푥푓), re-annihilation depletes the abundance: 푥 휇 2 ⇒ Ω ℎ2 ≈ 0.1 퐷 퐻෩ 25 1푇푒푉 Late decays of axino/saxion may over-produce Higgsino DM. 7 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Cosmic axino/saxion production 퐴 = (푠 + 푎, 푎෤) Sizable thermal generation although axino/saxions are too weakly interacting to be in thermal equilibrium: with EJC, 1104.2219 Bae, KChoi, Im, 1106.2452 −12 cf) 푌퐷푀~10 Bae, EJC, Im, 1111.5962 8 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova DFSZ axino abundance Decay/inverse-decay & scattering: Resonant scattering 1111.5962 9 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Cosmic saxion production Coherent oscillation with initial amplitude s0 = Fa : 10 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Higgsino dumping from axino/saxion decays Late decays of axino/saxion may produce over-abundant Higgsino DM after its freeze-out: Note) EJC, Lukas, ‘95 11 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Benchmark study with radiative natural SUSY Baer, et.al., 2012 Higgsino LSP underabundant 12 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Axion-Higgsino composition Bae, Baer, EJC, 1309.0519; 1309.5365 13 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Characteristics depending on Fa 10 12 Low Fa region: 10 – 10 GeV. Saxion/axino decay before neutralino freeze-out Standard neutralino density (10%)+axion density (90%) 12 13 Intermediate Fa region: 10 – 10 GeV. Saxion/axino decay after neutralino freeze-out Augmented neutralino (10-100%) + axion (90-0%) 13 16 High Fa region: 10 – 10 GeV. Overclosing neutralinos even after re-annihilation Saxion oscillation produces sizable dark radiation (axion) 14 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Higgsino detection 15 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Axion detection CAPP B=25~35T Q> x10 V> x50 2018-2020 16 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Summary Resolution of the mu, strong CP and Higgs fine-tuning problems leads to “SUSY with light Higgsino and DFSZ axion”. Long-lived saxion & axino are produced copiously through thermal generation/coherent oscillation. Light Higgsino abundance is determined by the standard freeze-out or re- annihilation caused by late decays of axino/saxion. 10 13 Mixed axion/Higgsino DM realized for Fa =10 – 10 GeV Signals in LUX/Zenon+ADMX/CAPP? 17 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Back-up 18 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Axino/saxion mass SUSY breaking induces axino/saxion mass. Model-dependent SUSY and PQ symmetry breaking: EJC, Kim, Nilles, ‘92 EJC, Lukas, ‘95 Axino mass is typically m3/2 but can be much lighter. Saxion mass is around m3/2. 19 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova Saxion/axino decays Saxion has generically order-one couplings to axions/axinos: Saxion to Higgs/Higgsinos: Axino to Higgs and Higgsino: 20 "Mixed Axion/Higgsino DM" EJChun@KIAS 2016-09-14 Padova.