Asymmetric Dark Matter & (Self) Interactions John March-Russell Oxford University GGI Florence, 2013 work w/ Stephen West, James Unwin, & earlier with Lawrence Hall, Matthew McCullough
Dark Matter Genesis? Dark matter WIMPs: Calculable thermal freeze-out with scale v FIMPs: Calculable thermal freeze-in with scale v Axions: Mis-alignment or thermal production Asymmetric DM & Baryons Sharing Co-genesis
Motivation Baryons need origin of particle-antiparticle asymmetry η B = Y B − Y ¯ B m B η B ∼ sin φ m 2 ν M R M P l Λ QCD v 4 CP-violating phase Usual, unrelated origin of baryons & DM, involving very different physics, makes it hard to understand Ω DM / Ω B ' 4 . 86 Freeze-out dominates thinking about DM candidates, detection, and LHC phenomenology
Are we being misled?
ADM Basics Alternative: similar physics underlies both and Ω B Ω DM (Nussinov ’85; Gelmini, Hall, Lin ’87; Barr ’91; Kaplan ‘92; Thomas ’95; Hooper, JMR, West ’04; explosion in last 3yrs esp work of Zurek etal; now many others...) Baryons: U (1) B p stable u, d, s... Ω B ∝ m B η B DM: U (1) X X 0 , X 1 , X 2 ... X 0 stable Ω X ∝ m X η X Interactions violate B and X to yield At some era related values for and η X η B Ω X = η X m X Ω B η B m B
ADM Basics Ω X only true if X density is determined = η X m X by the asymmetric part otherwise Ω B η B m B Ω X = Y X + Y ¯ m X X Ω B Y B + Y ¯ m B B need Y X + Y ¯ X = Y X − Y ¯ X + small corrections X = Y X − Y ¯ non-trivial constraint as initially X Y X + Y ¯ � where measures ✏ ≤ sin( � eff ) × loop factor CP-violation
ADM Basics Two general categories of theories: “sharing” & “co-generation” T T R Unspecified primordial generation Negligible primordial generation Vis Dark Dark Vis T T � T v η X ∼ η B by sharing η X ∼ η B by co-generation Co-generation is more ambitious: attempts to explain simultaneous origin of B & X asymmetries (if at scale ~ TeV allowing test at LHC...)
ADM Basics Sharing: T Arbitrary initial L X Assumes presence of some initial η X η B , η L asymmetry in (at least) one of B, L & X η 10 12 GeV EW anomaly breaks A “portal interaction” breaks a combination of B/L & X, such that B + L 10 2 GeV there is an era when only conserved U(1) is ed U(1) is η B : η L : η X = N 1 : N 2 : N 3 B − L + X ⇒ = X
ADM Basics Co-generation: T Arbitrary initial η B = η L = η X = 0 L X zero initial asymmetry in B, L & X η X η B , η L η 10 12 GeV EW anomaly “Connector interactions” both break a combination breaks of B/L & X, and lead to generation of asymmetry which is simultaneously shared (further later sharing due to B + L EW anomaly can occur too) 10 2 GeV ed U(1) is X
ADM Basics Alternative view (either sharing or co-generation): incompatible with standard SUSY Majorana neutralino DM changes one or both direct/indirect DM detection co-generation harder as requires B, X violation & out-of- equilibrium condition (at TeV scale if testable). Requires a new theory of calculable (thermal) DM production....
ADM Basics Must efficiently annihilate away symmetric part to light states ⇒ = there has to be an efficient X-preserving freeze-out process Three options: direct FO to light SM dof operators connecting X & SM sectors with strength bounded below ⇒ = direct FO to light dark sector dof (potentially) new long-range DM interactions ⇒ = FO to dark sector dof which then late decay to SM late-time energy injection in early universe ⇒ =
FO Portal direct FO of symm yield to light SM dof limits from direct detection experiments and monojet searches at Tevatron and LHC are very constraining
Use effective operators to parameterise portal interactions. Some are suppressed by: v velocity of q < 0.1GeV mom’m
we shall examine CP-violating ops
m_q dep’t ops direct detection constrained
ADM relic density - removal of symmetric component: ⇣ m DM Ω DM h 2 ' 3 ⇥ 10 8 ( Y sym + Y asym ) ⌘ GeV By assumption relic density must be due to the asymmetry, so demand symmetric component <10% of asymmetric part (results relatively insensitive to 0.1% vs 100%) Yields depend on (presumed known) asymmetry and FO cross section η X η X Y DM ∼ Y DM ∼ h ⇣ ⌘i h ⇣ ⌘i a b a b exp x F + − 1 1 − exp x F + η X ω − η X ω x 2 x 2 ¯ ¯ ¯ ¯ F F √ g ∗ and h σ v i = a + 6 b where ω = 4 π 90 m DM M Pl x + · · · √
Example: relic density requirement on m q Λ 3 ψψ qq 10 4 ! 3 / 2 1 − m 2 b = 3 m 2 q X X m 2 a = 0 q m 2 8 π Λ 6 X q 1000 L H GeV L 100 allowed region is below line 10 ` y : m q L 3 y y q q O s 1 1 10 100 1000 10 4 m DM H GeV L
Constraints from direct detection (CRESST, DAMIC, CDMS, XENON100) 10 4 1000 L H GeV L 100 10 allowed region is above coloured lines ` y : m q L 3 y y q q O s 1 1 10 100 1000 10 4 m DM H GeV L ADM in preferred 1-10GeV region excluded with this op ⇒ =
m q Portal operator is an easy case as direct detection Λ 3 ψψ qq not SD and not v- or q- suppressed Monojet searches provide complementary constraints on DM with interactions with quarks (e.g. Bai, Fox, Harnik arXiv:1005.3797)
Constraints on q- or v-suppressed ops 10 4 10 4 10 4 1000 1000 1000 L H GeV L L H GeV L L H GeV L 100 100 100 10 10 10 y : y : L 2 y g 5 y q g 5 q 1 ` L 2 y g m y q g m g 5 q i y : m q O p L 3 y g 5 y q g 5 q O va O p 1 1 1 1 10 100 1000 10 4 1 10 100 1000 10 4 1 10 100 1000 10 4 m DM H GeV L m DM H GeV L m DM H GeV L 10 4 10 4 10 4 1000 1000 1000 L H GeV L L H GeV L L H GeV L 100 100 100 10 10 10 y : f : i L 2 y g m g 5 y q g m q y : L 2 y s mn y q s mn q 1 i O av L 2 f † ∂ m f q g m g 5 q O t O va 1 1 1 1 10 100 1000 10 4 1 10 100 1000 10 4 1 10 100 1000 10 4 m DM H GeV L m DM H GeV L m DM H GeV L
Constraints on SD operators 10 4 10 4 1000 1000 L H GeV L L H GeV L 100 100 10 10 y : 1 y : L 2 y s mn y q s mn q 1 L 2 y g m g 5 y q g m g 5 q O t O a 1 1 1 10 100 1000 10 4 1 10 100 1000 10 4 m DM H GeV L m DM H GeV L
Constraints on SI operators 10 6 10 4 10 4 10 5 1000 1000 10 4 L H GeV L L H GeV L L H GeV L 1000 100 100 100 10 10 10 ` y : f : m q 1 1 f : L f † f q q L 2 f † f q q O s L 2 y y q q O s O s 1 1 1 1 10 100 1000 10 4 1 10 100 1000 10 4 1 10 100 1000 10 4 m DM H GeV L m DM H GeV L m DM H GeV L 10 4 10 4 1000 1000 L H GeV L L H GeV L 100 100 10 10 1 f : 1 y : L 2 y Γ Μ y q g m q L 2 f † ∂ m f q g m q O v O v 1 1 1 10 100 1000 10 4 1 10 100 1000 10 4 m DM H GeV L m DM H GeV L
direct FO of symm yield to light SM dof limits from direct detection experiments and monojet searches at Tevatron and LHC are very constraining Main way to avoid these constraints: Non-minimal flavour structure: e.g. isospin violating or tau-philic, or very special choice of operator... with ugly exceptions if we want asymmetric DM in natural region then direct FO to SM is disfavoured m X < 10 GeV = ⇒ eliminating symm yield likely implies new dark-sector dynamics involving further light states
Crucial question how light?
`Midi’ Mass Mediators With mediators < few 100 GeV effective operator description breaks-down at LHC and previous results no longer valid Resonances and mass thresholds are important Large effects on the monojet limits and relic density calculation Notably, constraints from monojet limits are greatly relaxed Direct detection limits are unaffected for mediators >100 MeV as bigger than mom’m transfer & effective op is still good
Example: scalar midi mediator Consider a scalar mediator with couplings to quarks due to mixing with the SM Higgs θ ∼ m η m H L ⊃ λ X η ¯ X ( λ 0 θ y q ) η ¯ ψψ + qq q 10 10 1 1 0.1 0.1 l X l X 0.01 0.01 m h = 50 GeV m h = 10 GeV 0.001 0.001 5 10 20 50 5 10 20 50 100 m DM m X Monojet constraints relaxed, but direct detection limits remain unless in resonance region
Such midi-mass mediating states logically possible and still marginally allow ADM with some fine-tuning (rather like traditional WIMPs) However a much more interesting possibility in my opinion is that there are very light states in dark sector, like photon or pion/axion in our sector = ⇒ much richer dark-matter dynamics with astrophysical advantages (and signals) (also potential signals in direct and indirect detection, and precision particle phys expts)
Light Dark Sector States This leads to a rich and potentially extremely complicated set of possible consequences Here I’ll discuss only the very simplest... Suppose there exists a single v. light self-conjugate DS state Y coupling to ADM and which is stable or metastable What mass should it have? Maintaining ADM relation for DM X = Y X − Y ¯ X density given symm yield Y X + Y ¯ � = ⇒ m Y < ✏ 10 m X
α X ≡ λ 2 symmetric component annihilates to Y and the coupling 4 π must satisfy 0.014 0.012 0.010 0.008 Α X 0.006 0.004 0.002 0.000 0 5 10 15 20 m X Minimum for efficient annihilation for scalar (blue), & derivatively coupled pseudoscalar (red) mediator (in pseudoscalar case ) λ ≡ m x /f
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