Dark radiation from the axino solution of the gravitino problem
Jasper Hasenkamp (Hamburg U.)
at DESY Theory Workshop 2012 (Hamburg, Germany)
University of Hamburg (Germany)
Based on Phys. Lett. B 707, 121-128 (2012), [arXiv:1107.4319].
27th September 2012 Motivation Axino solution Emergence of dark radiation Summary
New observation opportunity for physics beyond the two standard models
Bounds on radiation energy density ρrad in terms of the effective number of neutrino species Neff defined by
4 1 7 Tν Tν ` 4 ´ 3 ρ = 1 + N ργ with = . rad eff 8 Tγ Tγ 11
Departure ∆Neff from standard cosmology making use of the Standard Model parameterised as
SM SM Neff = Neff + ∆Neff with Neff ' 3.
ρrad affects expansion ⇒ ∆Neff can be constrained. Independent measurements probing different cosmological times → reveal time evolution of ∆Neff 6= increasing Neff by, e.g., additional thermal species.
New observation opportunity to reveal an evolution of Neff
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 2 / 11 Motivation Axino solution Emergence of dark radiation Summary
Current/ongoing observations
4He formed ∼ 1 s → big bang nucleosynthesis (BBN) lasts ∼ 20 min
BBN ∗ SM Neff ≤ 4 (95% CL) → consistent with Neff
100 ky later Universe becomes transparent for photons → cosmic microwave background (CMB):
CMB † (ACT+WMAP+BAO+H0) Neff = 4.56 ± 0.75 (68% CL) → ∆Neff ∼ 1.5
CMB ‡ (SPT+WMAP+BAO+H0) Neff = 3.86 ± 0.42 (68% CL) → ∆Neff ∼ 0.81
∗ [Mangano, Serpico, 11] consistent with earlier studies, e.g. [Simha,Steigman, 08]. Under discussion, see [Aver, Olive, Skillman, 10] & [Izotov, Thuan, 10]. † Atacama Cosmology Telescope (ACT) data analysis [Dunkley et al., 10] using WMAP7. ‡ South Pole Telescope (SPT) data analysis [Keisler et al., 11] using WMAP7.
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 3 / 11 Motivation Axino solution Emergence of dark radiation Summary
Current/ongoing observations
SM ⇒ everything consistent with Neff → only hint of tension
∗ → Planck satellite → ∆Neff ' 0.26 precision
⇒ 3- to 5-σ if current central values accurate!
Planck mission could turn the hint into a discovery
∗ [Perotto, Lesgourgues, Hannestad, Tu, Wong, 06] & [Hamann, Lesgourgues, Mangano, 08]
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 4 / 11 Motivation Axino solution Emergence of dark radiation Summary
Gravitino, axino, axion,...
Gravitino Ψ3/2 inevitable prediction of any local supersymmetric theory → gravitational interactions only ⇒ gravitino problem
Standard solution of the strong CP problem: Peccei-Quinn mechanism susy 9 → introduces axion a −−−→{a, φsax, ae} with LPQ ∝ 1/fa, where fa & 10 GeV
Ψ3/2 → ... or ae → ... OR
∗ LOSP → Ψ3/2 + SM particle or LOSP → ae + SM particle
after tBBN may dissociate formerly build nuclei →
Decays after tBBN endanger its success ∗ LOSP = lightest ordinary supersymmetric particle= lightest particle in MSSM
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 5 / 11 Motivation Axino solution Emergence of dark radiation Summary
Gravitino decay into decoupled decay products
with m m > m gravitino decays invisibly [Asaka,Yanagida, 00] losp & 3/2 ea
Ψ3/2 → ae + a as m , m m ⇒ emission with relativistic momenta ⇒ dark radiation a ea 3/2
LOSP (bino,Higgsino,stau,...)∗ → ae + SM particle ⇒ no gravitational decay ⇒ LOSP decay problem drastically softened
Light axino solves the gravitino problem
∗ bino: [Baer, Kraml, Lessa, Sekmen, 11]; stau: [Freitas, Steffen, Tajudddin, Wyler, 11]; Higgsino,wino,...: [JH, 11] using [JH, Kersten, 11] & [Covi, JH, Pokorski, Roberts, 09]
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 6 / 11 Motivation Axino solution Emergence of dark radiation Summary
Dark radiation from invisible gravitino decay at the right time...
Ψ3/2 decays with lifetime τ3/2 emitting relativistic axion and axino
2 3 t end ∗ ∼ 103 s < τ ' 109 s 10 GeV < 5 × 1010 s ' τ max † BBN 3/2 m3/2 CMB
Gravitino decays naturally at the right time
∗ See [Menestrina, Scherrer, 11] for decay during BBN. † [Fischler, Meyers, 11]
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 7 / 11 Motivation Axino solution Emergence of dark radiation Summary
...and with the “right” amount
5 2 102 GeV 2 m T ∆ ' . ge R → O ( )! Neff 0 6 10 1 m3/2 1 TeV 10 GeV
1) ∆N (m , m , T ) only → m , Y tp (m , m , T ), τ (m ) eff 3/2 eg R 3/2 3/2 3/2 eg R 3/2 3/2
2) gluino-gravitino mass gap natural for mlosp & m3/2
11 3) new upper bound on reheating temperature TR . 10 GeV → no upper bound from entropy production (dark radiation does not thermalize)
Thermal leptogenesis might predict desired increase in Neff
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 8 / 11 Motivation Axino solution Emergence of dark radiation Summary
TR - m3 2 1013
1012
1011 D
10 GeV 10 @ R T
109
4 5 mgluino = 550 GeV 10 GeV 10 GeV 108
107 1 10 102 103 104 105
m3 2 GeV
@ D Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 9 / 11 Motivation Axino solution Emergence of dark radiation Summary
...and dark matter
Three consistent cosmologies:
12 1) Natural cold axion dark matter: fa ∼ 10 GeV → no bino LOSP and m ∼ O (keV)∗ to avoid overproduction. ea 10 2) Warm axino dark matter: smaller fa ∼ 10 GeV ⇒ Ωa 1 and ksvz dfsz Ω > 1 → Ω ∼ ΩDM with m > O (keV). ea ea ea 12 3) Beyond LHC: fa 10 GeV not forbidden with correspondingly heavier sparticles (not natural) → beyond LHC discovery range → LHC can not exclude the scenario.
Natural cold axion (warm axino) dark matter
∗ Axino mass model dependent, c.f. [Tamvakis, Wyler, 82] & [Goto, Yamaguchi, 92] & [Chun, Kim, Nilles, 92] & [Kim, Seo, 12].
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 10 / 11 Motivation Axino solution Emergence of dark radiation Summary
Summary
i no constraints from and on saxion except φsax as in [JH, Kersten, 11] safe against other decay channels
independent of R or R/
natural cold axion (warm axino) dark matter (LOSP and Ψ3/2 decay)
thermal leptogenesis might predict a desired increase in Neff ⇒ Prediction from a consistent cosmology!
High testability: LHC→ m , Planck→ ∆NCMB > 0 ⇒ gravitino problem eg eff a fortune ⇒ m3/2 tightly constrained ⇒ TR as well
Even though Ψ3/2 and ae elusive and TR experimentally not accessible → prediction testable with on-going experiments
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 11 / 11 Thank you for your attention!
Hopefully, there are comments/questions?
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 12 / 11 Backup slides
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 13 / 11 LOSP decay...
LOSP (bino,Higgsino,stau,...)∗ → ae + SM particle ⇒ BBN constraints! ∆Nlosp decay 1 and Ωlosp decay 1 X eff ea → early enough decay → possible mass bounds and upper bound on fa 1 3 max ! 2 m 2 τ f 1010 GeV Be Be a . 100 GeV 10−2 s
wino/Higgsino LOSP → τ max ∼ (102–103) s 12 , → fa > 10 GeV and mlosp ∼ m3/2 allowed DFSZ dim-4 operators to He-h and sfermion-fermion 12 , → fa > 10 GeV and mlosp ∼ m3/2 allowed
LOSP decay safe and allows for large fa and mlosp ∼ m3/2
∗ bino: [Baer, Kraml, Lessa, Sekmen, 11]; stau: [Freitas, Steffen, Tajudddin, Wyler, 11]; Higgsino,wino,...: [this work] using [JH, Kersten, 11]/talk[] & [Covi, JH, Pokorski, Roberts, 09]
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 14 / 11 The gravitino Ψ3/2 inevitable and unique prediction of any local supersymmetric theory.
i) msoft ∼ m3/2 (gravitino mass m3/2 = gravity mediated contribution) ii) gravitational interactions only 3 ⇒ τ3/2> years × (100 GeV/m3/2) 1 s ∼ tBBN tp iii) produced in thermal scatterings Ω3/2 (ΩDM ' 0.2): 100 GeV T m 2 Ωtp ∼ . R ge 3/2 0 2 10 m3/2 10 GeV 1 TeV
⇒ (2nd) gravitino problem: upper bound on energy released by particle 5 decays after tBBN ⇒ TR < 10 GeV 10 → gravitino LSP = perfect dark matter for TR ∼ 10 GeV
Gravitino dark matter turns gravitino problem into a virtue Not the only opportunity! → see ”dark radiation”
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 15 / 11 The strong CP problem
QCD has rich vacuum structure → LΘ ∼ ΘGGe ⇒ CP violation CP violation constrained by neutron electric dipole moment:
−10 Θe = Arg Det Mquarks + Θ . 10 , while Arg Det Mquarks 6= 0!
⇒ Why should a sum of two independent parameters result in zero? → fine-tuning problem of Standard Model QCD
Standard solution ”Peccei-Quinn (PQ) mechanism“:
spontaneous symmetry breaking of U(1)PQ ⇒ Θe dynamically 0
QCD is (still?) our best confirmed particle theory ⇒
Solution to strong CP problem should be enabled
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 16 / 11 The axion multiplet
spontaneous symmetry breaking ⇒ Goldstone boson susy → axion a −−−→{a, φsax, ae} 9 i) LPQ ∝ 1/fa, where fa & 10 GeV from super nova cooling ii) ma ∼ µeV (Goldstone boson), msax ∼ msoft (SUSY breaking), ∼ or down to O (keV )∗ mea msoft iii) copious production in a) thermal scatterings → Ω ∝ m × n n: number density 2 b) coherent vacuum oscillations → Ω ∝ φi φi : initial displacement i)–iii) ⇒ φsax and ae typical late-decaying particles (cp. Ψ3/2)
⇒ cosmological problems
Solving strong CP problem poses cosmological problems itself
∗ [Tamvakis, Wyler, 82], [Goto, Yamaguchi, 92] & [Chun, Kim, Nilles, 92]
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 17 / 11 Thermal leptogenesis
lepton asymmetry from decays of thermally produced heavy neutrinos νR. → consequence of see-saw mechanism (tiny neutrino massesX)
SM sphalerons convert lepton asymmetry into baryon asymmetry ηB
M ηmax ∼ 6 × 10−10 νR ∼ ηobs B 2 × 109 GeV B
9 ⇒ successful thermal leptogenesis ⇒ MνR > 2 × 10 GeV 9 → thermal production efficient for TR & MνR → TR > 2 × 10 GeV
Thermal leptogenesis simple and elegant origin of matter
MνR = lightest Majorana mass of right-handed neutrinos.
Dark radiation from the axino solution of the gravitino problem Jasper Hasenkamp 18 / 11