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 + 𝑖푎, 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