Direct Detection Signals from Absorption of Fermionic Dark Matter - - PowerPoint PPT Presentation

Direct Detection Signals from Absorption of Fermionic Dark Matter

Gilly Elor

University of Washington, Seattle

Jeff Dror, GE, Robert McGehee [1905.12635] submitted to PRL Jeff Dror, GE, Robert McGehee [1908.xxxxx] nuclear targets Jeff Dror, GE, Robert McGehee, Tien-Tien Yu [19xx.xxxxx] electron targets

Searching for new physics - Leaving no stone unturned!

University of Utah, August 5 2019

Based on:

Dark Matter exists.

DM DM SM SM

Searching for Dark Matter

Dark Matter - Standard Model Interaction

DM DM SM

Production at Colliders

SM

Searching for Dark Matter

Indirect Detection (today)

DM DM SM

Production at Colliders D i r e c t D e t e c t i

• n

SM

Searching for Dark Matter

Indirect Detection (today)

Today’s Talk

mχ ⇠ 10 GeV - 10 TeV

Vanilla WIMP:

• Interacts via weak force
• Stable

Direct Detection Searches:

x recoil energy: T χ χ T Λ

χ

N N

χ χ

MW

• Elastic Scattering: DM imparts kinetic

energy on nuclei

• Measure nuclear recoil
• Order keV experimental thresholds

ER ⇠ µ2v2 MN

Weakly Interacting Massive Particles

Snowmass Report 2013

We Have Not Found WIMPs

Ever smaller cross sections excluded while approaching the neutrino floor

Snowmass Report 2013

Light (sub-GeV) dark matter (LDM) below experimental nuclear recoil thresholds

Light Dark Matter

ER ∼ µ2v2/MT

(Model space is actually highly constrained [1709.07882])

• Interacts via weak force
• Stable

mχ ⇠ 10 GeV - 10 TeV

Vanilla WIMP:

Elastic scattering off electrons Lots of work has been done!

x recoil energy: T χ χ T Λ

χ

χ χ

e− e−

Λ

Need Lower Thresholds

Moving away from Vanilla WIMP: Lack of discoveries motivates us to move away from the simplest scenarios.

ER ∼ µ2v2/MT

• Interacts via weak force
• Stable

mχ ⇠ 10 GeV - 10 TeV

Vanilla WIMP:

Giving up Stability?

??

• Interacts via weak force
• Stable

mχ ⇠ 10 GeV - 10 TeV

Vanilla WIMP:

Giving up Stability?

??

Leaving no stone unturned!

• Interacts via weak force
• Stable

mχ ⇠ 10 GeV - 10 TeV

Vanilla WIMP:

Giving up Stability?

??

Signals from Absorption of fermionic Dark Matter

χ

Λ

ν

N, e− N, e−

• Distinctive new signals!
• Can repurpose existing DM

direct detection and neutrino experiments.

• No neutrino floor

Target can absorb fermionic DM rest mass

Neutral Current Charged Current

Absorption of Fermionic Dark Matter

ENR

χ

⇠ mχ + 1 2mχv2

χ

Λ

e± N

N

Γi ⌘ {1, γ5, γµ, γµγ5, σµν}

Fermion Absorption Operators

• Ex. UV Model*: Z’ mediator, lepton no. charged DM and Dirac neutrinos

χ Λ

ν

N, e− N, e−

Neutral Current: ONC = 1 Λ2 ⇥ ¯ χΓiν ⇤⇥ ¯ ψΓjψ ⇤ , ψ = p , n , e

OCC = 1 Λ2 ⇥ ¯ χΓie ⇤⇥ ¯ nΓjp ⇤

• Ex. UV Model*: L-R model vector mediator, lepton no. charged DM and Dirac neutrinos

Charged Current:

χ Λ

e± N

N

*For model building details see: “Absorption of Fermionic Dark Matter by Nuclear Targets” [1908.xxxxx]

Dark Matter Decays

Dark Matter Decays

¯ χσµννFµν

• Certain problematic operators leading to fast decays

can be suppressed e.g.

• Decays are model dependent: build UV models

which suppressed additional decay contributions.

• Minimum contribution to decay is independent of

UV model, but scales as powers of DM mass.

Dark Matter Decays

¯ χσµννFµν

• Certain problematic operators leading to fast decays

can be suppressed e.g.

• Decays are model dependent: build UV models

which suppressed additional decay contributions.

• Minimum contribution to decay is independent of

UV model, but scales as powers of DM mass.

„ ν χ p, n γ, Z e´, e`,

Dark Matter Decays

< mχ < 100 MeV

¯ χσµννFµν

• Certain problematic operators leading to fast decays

can be suppressed e.g.

• Decays are model dependent: build UV models

which suppressed additional decay contributions.

• Minimum contribution to decay is independent of

UV model, but scales as powers of DM mass.

„ ν χ p, n γ, Z e´, e`,

Dark Matter Decays

< mχ < 100 MeV

• Speaking of Elephants: Little hope to detect sterile neutrinos

τN→νγ / Λ2 / 1/s2

θ

¯ χσµννFµν

• Certain problematic operators leading to fast decays

can be suppressed e.g.

• Decays are model dependent: build UV models

which suppressed additional decay contributions.

• Minimum contribution to decay is independent of

UV model, but scales as powers of DM mass.

New Signals!

Neutral Current Signals: Nuclear Targets

χ Λ

ν

N, N,

JD, GE, RM [1905.12635] , [1908.xxxxx]

• Operators:

Neutral Current Signals: Nuclear Targets

ONC = 1 Λ2 ⇥ ¯ Γi⌫ ⇤⇥ ¯ nucΓj nuc ⇤ , nuc = p , n

χ Λ

ν

N, N,

JD, GE, RM [1905.12635] , [1908.xxxxx]

• Operators:

Neutral Current Signals: Nuclear Targets

ONC = 1 Λ2 ⇥ ¯ Γi⌫ ⇤⇥ ¯ nucΓj nuc ⇤ , nuc = p , n

χ Λ

ν

N, N,

• Kinematics:

Eν ∼ mχ and ET ∼

m2

2 MN

mχ << MN Dark matter rest mass is absorbed (kinetic energy negligible)

JD, GE, RM [1905.12635] , [1908.xxxxx]

• Operators:

Neutral Current Signals: Nuclear Targets

ONC = 1 Λ2 ⇥ ¯ Γi⌫ ⇤⇥ ¯ nucΓj nuc ⇤ , nuc = p , n

χ Λ

ν

N, N,

• Kinematics:

Eν ∼ mχ and ET ∼

m2

2 MN

mχ << MN Dark matter rest mass is absorbed (kinetic energy negligible)

• Signal:

Distinct from elastic scattering which recall is DM velocity dependent

dR dER ∝ δ ✓ ER − m2

χ

2MN ◆

• All events in one bin
• Isotope peaks
• No neutrino floor
• Sensitive to sub GeV DM masses

ER ⇠ µ2v2 MN

JD, GE, RM [1905.12635] , [1908.xxxxx]

s CaWO4 s CaW O4 aWO

Absorption vs Elastic Scattering Signals

is NC = m2

χ/

• 4⇡Λ4

ature of correlated, pe

crystals

Eelastic

∼ m2

MN Eabs

∼ m2

2MN vs

s CaWO4 s CaW O4 aWO

Absorption vs Elastic Scattering Signals

is NC = m2

χ/

• 4⇡Λ4

ature of correlated, pe

crystals

1905.12635 Robert McGehee

Neutral Current Projections

R = ⇢χ mχ NC X

j

NjA2

jF 2 j Θ(E0 R,j Eth).is NC = m2

χ/

• 4⇡Λ4

ature of correlated, pe 52 kg-days

• No. Events < 10

1905.12635 Robert McGehee

Mono-Jet searches [1807.03817]

Neutral Current Projections

Λ < 1 TeV

R = ⇢χ mχ NC X

j

NjA2

jF 2 j Θ(E0 R,j Eth).is NC = m2

χ/

• 4⇡Λ4

ature of correlated, pe 52 kg-days

• No. Events < 10

1905.12635 Robert McGehee

Neutral Current Projections

Isotopes nuclear recoil energy rises above experimental threshold

E0

R,j = m2 χ/(2MNj) > Eth

Λ < 1 TeV

R = ⇢χ mχ NC X

j

NjA2

jF 2 j Θ(E0 R,j Eth).is NC = m2

χ/

• 4⇡Λ4

ature of correlated, pe 52 kg-days

• No. Events < 10

1905.12635 Robert McGehee

Neutral Current Projections

Decays? e.g

Λ < 1 TeV

Γχ!νe+e

1905.12635 Robert McGehee

Neutral Current Projections

Decays? e.g

Λ < 1 TeV

Γχ!νe+e

Indirect Detection constraints [1309.4091]

⌫

• Z0

✏

• e

e+

ΓNC

Λ4

1905.12635 Robert McGehee

Neutral Current Projections

Λ < 1 TeV Indirect Detection constraints [1309.4091]

⌫

• Z0

✏

• e

e+

“Fine Tune “ away with a UV Kinetic Mixing

Decays? e.gΓχ!νe+e

ΓNC

Λ4

Neutral Current Projections

• No. Events < 10

Repurposing Existing Experiments

σNC . 10mχ ρχ

• Ave. Isotope mass

Fiducial Mass ⇥ Run Time

Neutral Current Hypothetical Experiments

Lighter targets and lower threshold to probe sub-MeV Dark Matter

by collective m Since ER / 1/M, this regime.

Neutral Current Hypothetical Experiments

Lighter targets and lower threshold to probe sub-MeV Dark Matter

by collective m Since ER / 1/M, this regime.

Γχ→νγγγ / mpower

χ

Indirect detection constraints:

• Z0

• e

No/little need for Fine Tuning.

Decays?

⇥ ⇤ ⇥ ⇤ 1 Λ2 ⇥ ¯ χΓµe ⇤ ⇥ ¯ nΓµp ⇤

Charged Current Signals

• Operators:

χ

Λ

e±

N

N

⇥ ⇤ ⇥ ⇤ 1 Λ2 ⇥ ¯ χΓµe ⇤ ⇥ ¯ nΓµp ⇤

• Operators:
• Kinematics:

χ

Λ

e±

N

N

Massive DM induces (otherwise stable) “Beta” transitions if:

mχ > mβ⌥

th ≡ M (⇤) A,Z±1 + me − MA,Z ,

Charged Current Signals

⇥ ⇤ ⇥ ⇤ 1 Λ2 ⇥ ¯ χΓµe ⇤ ⇥ ¯ nΓµp ⇤

• Operators:
• Kinematics:
• Signals:

χ

Λ

e±

N

N

Massive DM induces (otherwise stable) “Beta” transitions if:

mχ > mβ⌥

th ≡ M (⇤) A,Z±1 + me − MA,Z ,

β: χ + n → p + e ⇒ χ + N

ZX → N Z+1X + ⇤ + e

β+: ¯ χ + p → n + e+ ⇒ ¯ χ + N

ZX → N Z1X

• ⇤ + e+

Charged Current Signals

⇥ ⇤ ⇥ ⇤ 1 Λ2 ⇥ ¯ χΓµe ⇤ ⇥ ¯ nΓµp ⇤

• Operators:
• Kinematics:
• Signals:

χ

Λ

e±

N

N

Massive DM induces (otherwise stable) “Beta” transitions if:

mχ > mβ⌥

th ≡ M (⇤) A,Z±1 + me − MA,Z ,

β: χ + n → p + e ⇒ χ + N

ZX → N Z+1X + ⇤ + e

β+: ¯ χ + p → n + e+ ⇒ ¯ χ + N

ZX → N Z1X

• ⇤ + e+

Multiple correlated signals at DM and neutrino experiments Signatures depend on isotope and DM energy.

Charged Current Signals

Signals from Induced Beta Transitions

χ + 128

54Xe ! 128 55Cs+ ⇤ + e

Example:

mβ−

th ⇠ 0.86 MeV

χ Λ

e±

+ 128

Signals from Induced Beta Transitions

ER ' ( mχ mβ

th

(electron)

• mχ mβ

th

2/2M (⇤)

A,Z+1

(nucleus)

• Emitted high energy electron/positron
• Recoiling nucleus
• Photon from excited nucleus
• Decay of unstable nucleus

Signals:

χ + 128

54Xe ! 128 55Cs+ ⇤ + e

Example:

mβ−

th ⇠ 0.86 MeV

Kinematics:

χ Λ

e±

+ 128

Signals from Induced Beta Transitions

χ + 128

54Xe ! 128 55Cs+ ⇤ + e

Example:

mβ−

th ⇠ 0.86 MeV

Angular Momentum Selection Rules for a given operator (Fermi, Gamow-Teller transitions etc.)

χ + 128

54Xe ! 128 55Cs+ ⇤ + e Ground state Excited state

χ Λ

e±

+ 128

Signals from Induced Beta Transitions

χ + 128

54Xe ! 128 55Cs+ ⇤ + e

Example:

mβ−

th ⇠ 0.86 MeV

Angular Momentum Selection Rules for a given operator (Fermi, Gamow-Teller transitions etc.)

Consider the vector operator: Fermi transitions dominate

Example (neutrino scattering result)

• P. Pirinen,1 J. Suhonen,1 and E. Ydrefors2

1 Λ2 ⇥ ¯ χγµe ⇤ ⇥ ¯ nγµp ⇤ + h.c.

Ground state Excited state

χ Λ

e±

+ 128

all the selection rule (∆π = 0, ∆I = 0)

e´

Signals from Induced Beta Transitions

χ + 128

54Xe ! 128 55Cs+ ⇤ + e

Example:

mβ−

th ⇠ 0.86 MeV

Angular Momentum Selection Rules for a given operator (Fermi, Gamow-Teller transitions etc.)

Consider the vector operator:

1 Λ2 ⇥ ¯ χγµe ⇤ ⇥ ¯ nγµp ⇤ + h.c.

Fermi transitions dominate

Ground state Excited state

χ Λ

e±

+ 128

all the selection rule (∆π = 0, ∆I = 0)

e´

Signals from Induced Beta Transitions

• Emitted high energy electron/positron
• Recoiling nucleus
• Photon from excited nucleus
• Decay of unstable nucleus

Signals:

χ + 128

54Xe ! 128 55Cs+ ⇤ + e

Example:

mβ−

th ⇠ 0.86 MeV

Angular Momentum Selection Rules for a given operator (Fermi, Gamow-Teller transitions etc.)

Ground state Excited state

χ Λ

e±

+ 128

e´

Signals from Induced Beta Transitions

• Emitted high energy electron/positron
• Recoiling nucleus
• Photon from excited nucleus
• Decay of unstable nucleus

Signals:

χ + 128

54Xe ! 128 55Cs+ ⇤ + e

Example:

mβ−

th ⇠ 0.86 MeV

Angular Momentum Selection Rules for a given operator (Fermi, Gamow-Teller transitions etc.)

Ground state Excited state

χ Λ

e±

+ 128

e´

Signals from Induced Beta Transitions

• Emitted high energy electron/positron
• Recoiling nucleus
• Photon from excited nucleus
• Decay of unstable nucleus

Signals:

χ + 128

54Xe ! 128 55Cs+ ⇤ + e

Example:

mβ−

th ⇠ 0.86 MeV

Angular Momentum Selection Rules for a given operator (Fermi, Gamow-Teller transitions etc.)

Unstable Isotope of Cesium τ1/2 ⇠ 3.4 min Ground state

χ Λ

e±

+ 128

e´

Signals from Induced Beta Transitions

• Emitted high energy electron/positron
• Recoiling nucleus
• Photon from excited nucleus
• Decay of unstable nucleus

Signals:

χ + 128

54Xe ! 128 55Cs+ ⇤ + e

Example:

mβ−

th ⇠ 0.86 MeV

Angular Momentum Selection Rules for a given operator (Fermi, Gamow-Teller transitions etc.)

Unstable Isotope of Cesium τ1/2 ⇠ 3.4 min Ground state

Correlated signatures depend on a given isotope and experiment as well as DM energy.

χ Λ

e±

+ 128

Dark Matter Induced Beta Transitions

At Existing Experiments

χ

Λ

e± N

N

mχ > mβ⌥

th ≡ M (⇤) A,Z±1 + me − MA,Z ,

As with NC signals, large volume/exposure experiments will do best

Note ~1MeV Thresholds

Experiment Physics goal Exposure Isotope Abundance XENON1T DM 1.0 ton · yrs Liquid

Natural LUX DM 91.8kg · yrs Liquid

Natural EXO-200 0ν2β 233 kg · yrs Liquid 136

80% PandaX-II DM and 0ν2β 147.9 kg · yrs Liquid

Natural KamLAND-Zen 0ν2β 504 kg · yrs

91% CDMS-II DM 612 kg · d

Natural Borexino solar ν 817 t yra C6H3 (CH3)3 800 keVb Super Kamiokande ν 171,000 t yr H2O Natural DarkSide-50 DM 6786 kg d Liquid Ar Cuore 0ν2β 86.3 kg-yrs TeO2 crystals Natural Process Isotope (Threshold) β−:

β+:

At Existing Experiments

χ

Λ

e± N

N

mχ > mβ⌥

th ≡ M (⇤) A,Z±1 + me − MA,Z ,

As with NC signals, large volume/exposure experiments will do best

Note ~1MeV Thresholds

Experiment Physics goal Exposure Isotope Abundance XENON1T DM 1.0 ton · yrs Liquid

Natural LUX DM 91.8kg · yrs Liquid

Natural EXO-200 0ν2β 233 kg · yrs Liquid 136

80% PandaX-II DM and 0ν2β 147.9 kg · yrs Liquid

Natural KamLAND-Zen 0ν2β 504 kg · yrs

91% CDMS-II DM 612 kg · d

Natural Borexino solar ν 817 t yra C6H3 (CH3)3 800 keVb Super Kamiokande ν 171,000 t yr H2O Natural DarkSide-50 DM 6786 kg d Liquid Ar Cuore 0ν2β 86.3 kg-yrs TeO2 crystals Natural Process Isotope (Threshold) β−:

β+:

Dark Matter Induced Beta Transitions

Projected limits at Existing Experiments

⌧ R = ⇢χ 2mχ X

NT,j (Aj Zj) |~ pe|3

2⇡Λ4(mχ mβ

• No. Events < 10

Dark Matter Induced Beta Transitions

Λ < 1 TeV

Projected limits at Existing Experiments

⌧ R = ⇢χ 2mχ X

NT,j (Aj Zj) |~ pe|3

2⇡Λ4(mχ mβ

• No. Events < 10

Dark Matter Induced Beta Transitions

e

• W 0

W ⌫ e+

ΓNC

Λ4 Indirect detection constraints:

Decays?

ΓCC

Λ4 ✓mumd m2

◆2

compare with: Λ < 1 TeV

Projected limits at Existing Experiments

⌧ R = ⇢χ 2mχ X

NT,j (Aj Zj) |~ pe|3

2⇡Λ4(mχ mβ

• No. Events < 10

Note thresholds prevent us from significantly probing sub-MeV masses

Dark Matter Induced Beta Transitions

Λ < 1 TeV

Beta Decay Spectrum Shifts

• Threshold-less signal: probe sub-MeV DM masses
• For scattering on materials whose Beta decays which are unstable we will

see a shift in the kinematic spectrum e.g.

• Lack of existing large volume experiments using unstable target materials

3H → 3He + e− + ¯

νe, χ + 3H → 3He + e−.

Search for Tritium capturing incoming dark matter

⌘

• Ke =

⇣ m3H me + mχ ⌘2 m2

2 ⇣ m3H + mχ ⌘ .

In Summary: New Signals!

• Light decaying fermionic dark matter can lead to a variety of new signals through

absorption.

• Neutral current signals are distinctly different from elastic scattering (peaks, don’t need

low thresholds).

• Charged current operators can result in beta transitions.
• Current dark matter direct detection experiments and neutrino experiments can be

repurposed to search for these signals.

• Models relatively unconstrained by collider and cosmological bounds.

In Summary: New Signals!

• Light decaying fermionic dark matter can lead to a variety of new signals through

absorption.

• Neutral current signals are distinctly different from elastic scattering (peaks, don’t need

low thresholds).

• Charged current operators can result in beta transitions.
• Current dark matter direct detection experiments and neutrino experiments can be

repurposed to search for these signals.

• Models relatively unconstrained by collider and cosmological bounds.

Stay Tuned:

• Electron Targets Jeff Dror, GE, Robert McGehee, Tien-Tien Yu [19xx.xxxxx]
• Probes of Leptogenesis Jeff Dror, GE, Robert McGehee, Ann E. Nelson [19xx.xxxxx]

Thanks!

Backups

Experiment Physics goal Exposure Target Nuclear Recoil Threshold Refs XENON1T DM 1.0 ton · yrs Liquid Xe 3 keV [48] DarkSide-50 DM 6786 kgd Liquid Ar 0.6 keV [49] [50] CRESSTIII DM 2.39 kgd CaWO4 crystals 100 eV [42] CRESSTII DM 52 kgd CaWO4 crystals 307 eV [51] PICO-60 DM 1167 kgd Superheated C3F8 3.3 keV [52] PICO-60 DM 3420 kgd Superheated CF3I 13.6 keV [53] NEWS-G DM 9.7 kgd Neon 720 keV [54] DAMIC DM 0.6 kgd Si CCDs 0.7 keV [55] Borexino solar ν 817 ton-yrs C6H3 (CH3)3 200 keV [56] SuperK Atm neutrino 171 kiloton-yrs Liquid H2O (purified) 3.5 MeV [57] COHERENT CEνNS 6726 kgd CsI[Na] 6.5 keV [58] [59] Cuore 0ν2β 86.3 kg-yrs TeO2 crystals 100 keV [60]

TABLE II: Experiments which can probe fermionic DM absorption signals. Nuclear recoil thresholds are predominantly relevant for neutral current DM absorption, in which the only signal is nuclear recoil.

Experiments

13

Fermi

Gamow-Teller

1st forbidden

2nd forbidden

TABLE II. Every isotope which dominantly β decays (≥ 50 % BR) and has a half-life between 108 and 1013 seconds, categorized by their decay type [89]. Only Fermi and Gamow-Teller transitions are not momentum-suppressed for our charged current

• perators and therefore of interest to us.

Isotopes which Beta Minus Decay

• Fermi Transitions:

all the selection rules s (∆π = 0, ∆I = 0),

• Gamow-Teller Transitions:

i transitions (∆π = 0, ∆I s (∆π = 0, ∆I = 0, ±1),

• 1st forbidden:

itions (∆π = 0, ∆I = 0, ±1), s (∆π = 1, ∆I = 0, ±1, ±2),

• 2 nd forbidden:

± ± s (∆π = 0, ∆I = ±2, ±3),