Axion Portal ⌘ [Weinberg, Wilczek, KSVZ, DFSZ] �4 EFT for a (Neutral) Dark Sector

Snowmass RF6 - August 12, 2020

Dark Sector Portals at High Intensity

Adam Ritz University of Victoria

– New physics in a dark sector Empirical evidence for new physics, e.g. neutrino mass, dark matter, arguably points to a dark/hidden sector (but not directly to a specific mass scale) mediators Standard Model Dark Sector

May contain light states, if UV Physics sufficiently weakly coupled • Neutrino mass - (HL)(HL)/ΛUV • DM - WIMPs etc

Discoverability frontier

IR Physics Direct • Neutrino mass - light (RH) singlets searches • DM - axions, sterile neutrinos, etc EnergyFrontier

Visibility Frontier

➠ Dark sectors present a huge model-space a priori, but an EFT approach to the mediator channel allows for a classification (large community effort over past decade) EFT for a (neutral) dark sector

mediators Standard Model Dark Sector (+ gravity) There are just three UV-complete relevant or marginal “portals” to a SM-neutral hidden sector, unsuppressed by the (possibly large) new physics scale Λ c 1 = n (SM) (med) = + L ⇤n Ok Ol Lportals O ⇤ n=k+l 4 ✓ ◆ X ✏ µ⌫ 2 ij 1 = B A0 H†H(AS + S ) Y L¯ HN ++ 2 µ⌫ N i j OO ⇤ Vector portal Higgs portal Neutrino portal ✓ ◆◆ [Okun; Galison & Manohar; [Patt & Wilczek] Holdom; Foot et al]

Many more UV-sensitive interactions at dim ≥ 5

3 EFT for a (neutral) dark sector

mediators Standard Model Dark Sector (+ gravity) There are just three UV-complete relevant or marginal “portals” to a SM-neutral hidden sector, unsuppressed by the (possibly large) new physics scale Λ c 1 = n (SM) (med) = + L ⇤n Ok Ol Lportals O ⇤ n=k+l 4 ✓ ◆ X ✏ µ⌫ 2 ij 1 = B A0 H†H(AS + S ) Y L¯ HN + 2 µ⌫ N i j O ⇤ Vector portal Higgs portal Neutrino portal ✓ ◆ [Okun; Galison & Manohar; [Patt & Wilczek] Holdom; Foot et al] 1 ˜ ˜ µ + tr(GG)+cF F F + c @µjA a + (dim 5) fa O ⇣ Axion portal ⌘ [Weinberg, Wilczek, KSVZ, DFSZ] 4 EFT for a (neutral) dark sector

cn (SM) (med) CERN PBC1 = = portals + L ⇤n Ok Ol L benchmarkO ⇤ cases n=k+l 4 ✓ ◆ X ✏ µ⌫ 2 ij 1 = B A0 H†H(AS + S ) Y L¯ HN + 2 µ⌫ N i j O ⇤ ✓ ◆ BC 1-3 BC 4-5 BC 6-8

1 ˜ ˜ µ + tr(GG)+cF F F + c @µjA a + (dim 5) fa O ⇣ BC 9-11 ⌘ 5 EFT for a (neutral) dark sector

✏ µ⌫ 2 ij 1 = B A0 H†H(AS + S ) Y L¯ HN + L 2 µ⌫ N i j O ⇤ Vector portal Higgs portal Neutrino portal ✓ ◆

Applications of the portals fields a, A’, S and N: • minimal models of neutrino mass, and leptogenesis • viable (and minimal) non-thermal cold DM candidates (sub MeV) • new `dark force’ mediators enabling sufficient annihilation of thermal relic MeV-GeV (hidden sector) dark matter in the early universe

6 EFT for a (neutral) dark sector

✏ µ⌫ 2 ij 1 = B A0 H†H(AS + S ) Y L¯ HN + L 2 µ⌫ N i j O ⇤ ✓ ◆ A2 3 6 < 2H ✏1 2loop 10 10 2 ⇠ mS

Relevant operator, but does not γ A’ induce further UV sensitivity in loops, which generically scale as A2 log ⇤

ee0 ✏1 loop log ⇤ ⇠ 12⇡2 7 EFT for a (neutral) dark sector

✏ µ⌫ 2 ij 1 = B A0 H†H(AS + S ) Y L¯ HN + L 2 µ⌫ N i j O ⇤ Vector portal Higgs portal Neutrino portal ✓ ◆

2 µ Av ij ✏A0 J µ EM 2 SJS vYN ⌫¯iNj mh

Universal couplings to EM/scalar currents at low energy, so hidden sector models have correlated observable effects

8 Signatures at the intensity frontier

mediators Standard Model Dark Sector

“Visible” and “hidden” signatures

• Precision corrections • Rare (invisible) decays, E/pmiss • Rare (visible) decays • Anomalous NC-like scattering • Astrophys/cosmology • Astrophys/cosmology

Overlap with searches for light DM

High intensity/luminosity experiments provide excellent sensitivity to

MeV-GeV mass mediators 9 Signatures at the intensity frontier

Standard Model Dark Sector

“Visible” and “hidden” signatures

Vector Higgs Neutrino Axion Visible BC1 BC4,5 BC6-8 BC 9-11 Invisible BC2 Scattering BC2

Consider BC1-7 here, with other BC’s in backup slides10 Vector portal

• Production channels /f – e+ e- → A’ γ – π, η, η’ → A’γ, D* → DA’ /f – Vector-meson mixing – Bremsstrahlung (e and p) – Drell-Yan, DIS 9 GeV proton fixed target

π0 ρ,ω

brem

Normalizedrate qq

[deNiverville et al ‘16] 11 Vector portal - signatures if Br(SM) ~ 1 Visible decays (e.g. A’ → dileptons) [Fabbrichesi et al ’20]

12 Vector portal - signatures if Br(SM) ~ 1 Visible decays (e.g. A’ → dileptons) [Fabbrichesi et al ’20]

Projections 13 Vector portal - signatures if Br(hid) ~ 1 Missing mass, E, or mtm - O(ε2) [Fabbrichesi et al ’20]

14 Vector portal - signatures if Br(hid) ~ 1 Missing mass, E, or mtm - O(ε2) [Fabbrichesi et al ’20]

BaBar (2017)

NA64 (2019)

Projections 15 Vector portal - signatures if Br(hid) ~ 1 Missing mass, E, mtm - O(ε2), or scattering - O(ε4) [Fabbrichesi et al ’20]

4D parameter space {mA’, mχ, ε, αD} 16 Vector portal - signatures if Br(hid) ~ 1 Missing mass, E, mtm - O(ε2), or scattering - O(ε4) [Fabbrichesi et al ’20]

BaBar

E137

NA64 LSND

Projections 4D parameter space {mA’, mχ, ε, αD} 17 Vector portal - signatures if Br(hid) ~ 1 Missing mass, E, mtm - O(ε2), or scattering - O(ε4)

[Berlin et al ’20]

4D parameter space {mA’, mχ, ε, αD} 18 Higgs portal - visible decays (λ=0)

• Production channels (S→f+f-) K, B decay [Boiarska et al '19] – Bremsstrahlung (p) Brem, DIS – K→πS, B→K(*)S – DIS

Weaker limits Seaquest above ~5 GeV from LEP

[PBC Beacham et al '19]

19 mS(GeV) Higgs portal - visible decays (Br(h->SS) ~ 0.01)

• Production channels (S→f+f-) K, B decay [Boiarska et al '19] – Bremsstrahlung (p) Brem, DIS – K→πS, B→K(*)S – DIS + Higgs decay

Weaker limits Seaquest above ~5 GeV are from LEP

[PBC Beacham et al '19]

20 mS(GeV) Higgs portal - invisible decays

• Production channels (S→f+f-) K, B decay [Boiarska et al '19] – Bremsstrahlung (p) Brem, DIS – K→πS, B→K(*)S – DIS

Thermal target excluded in minimal MeV-GeV mass DM model by K, B meson decays

[Krnjaic '15] [See also Boehm & Fayet; deNiverville et al ’12] 21 Neutrino portal - electron flavour • Production modes – π, K → lν, B → Xlν decays – Neutrino mixing – Z decay [PBC Beacham et al '19]

22 Neutrino portal - tau flavour • Production modes – π, K → lν, D, B → Xlν decays – Neutrino mixing – Z decay [PBC Beacham et al '19]

23 Discussion

Standard Model Dark Sector

UV Physics • EFT arguments focus attention on the Discoverability frontier UV-complete portal interactions • Considerable progress over past decade

➡ Are there clear coupling and mass Direct searches IR Physics targets in BC 1-11 for next-gen

EnergyFrontier intensity frontier searches? Visibility Frontier

Vector Higgs Neutrino Axion

Visible 2-loop scale… Mass > 5 GeV �-flavour…

Thermal target Thermal target Invisible (DOE light DM BRN) “excluded” Backup Material (additional PBC benchmark cases)

25 Vector portal - massless A’ (millcharge)

Ionization, Z decays

26 Neutrino portal - muon flavour • Production modes – π, K → lν, B → Xlν decays – Neutrino mixing – Z decay [PBC Beacham et al '19]

27 Axion portal (photon coupling) • Production channels – e+ e- → γ a – Primakov conversion – Pseudoscalar meson mixing – K, B meson decay [PBC Beacham et al '19]

28 Axion portal (fermion coupling) • Production channels – e+ e- → γ a – Primakov conversion – Pseudoscalar meson mixing – K, B meson decay [PBC Beacham et al '19]

29 Axion portal (gluon coupling) • Production channels – e+ e- → γ a – Primakov conversion – Pseudoscalar meson mixing – K, B meson decay [PBC Beacham et al '19]