Signatures of Dark Matter Earth-Scattering: from sub-GeV particles - - PowerPoint PPT Presentation

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Signatures of Dark Matter Earth-Scattering: from sub-GeV particles - - PowerPoint PPT Presentation

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Signatures of Dark Matter Earth-Scattering: from sub-GeV particles to WIMPzillas Bradley J. Kavanagh LPTHE - Paris VI DM Signatures Workshop, Odense - 12th June 2017 bkavanagh@lpthe.jussieu.fr @BradleyKavanagh NewDark Direct Detection Focus

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NewDark

@BradleyKavanagh bkavanagh@lpthe.jussieu.fr

Bradley J. Kavanagh LPTHE - Paris VI DM Signatures Workshop, Odense - 12th June 2017

Signatures of Dark Matter Earth-Scattering:

from sub-GeV particles to WIMPzillas

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Direct Detection

χ

Detector DM flux:

Focus on DM-nucleus scattering for now

Φχ = ρχ mχ vf(v) Convolve with DM-nucleus cross section to obtain nuclear recoil rate: dR dER ∝ ρχ mχ ∞

vmin

vf(v) dσ dER dv

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Standard Halo Model

Standard Halo Model (SHM) is typically assumed: isotropic, spherically symmetric distribution of particles with . Leads to a Maxwell-Boltzmann (MB) distribution (in the lab frame): ρ(r) ∝ r−2 fLab(v) = (2πσ2

v)−3/2 exp

  • −(v − ve)2

2σ2

v

  • Θ(|v − ve| − vesc)

[But see e.g. 1705.05853]

f(v) = v2

  • f(v) dΩv
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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Annual Modulation (Earth’s Orbit)

[1312.1355]

vEarth(t) = vSun + vE(t) vSun ≈ 230 km s−1 vE ≈ 30 km s−1 O(1-10%) annual modulation of DM flux Maximum in June, Minimum in December

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Daily Modulation (Earth’s Rotation)

vrot ≈ 0.5 km s−1 vEarth(t) = vSun + vE(t) + vrot(t)

221.2 221.4 221.6 221.8 222.0 222.2 222.4 222.6 1 2 3 4 5 6 vlab[km/s] t [sidereal day] SUPL ANDES LNGS SUL SOUTH POLE

[1611.00802]

Produces a very small diurnal modulation (amplitude less than 0.1%)

[1505.02615]

vlab

time [days]

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Gravitational Focusing (GF)

Also modify DM velocities due to gravitational focusing from Sun and Earth

Sun Earth

DM Wind June 1 Sept 1 March 1 Dec 1

[astro-ph/0608390, 1308.1953, 1405.2340]

GF due to Sun produces a %- level annual modulation, with different phase compared to Earth’s orbital speed

Daily modulation amplitude

Similar effect due to focusing from Earth, comparable to effects of Earth’s rotation.

[1505.02615]

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Gravitational Focusing (GF)

Also modify DM velocities due to gravitational focusing from Sun and Earth

Sun Earth

DM Wind June 1 Sept 1 March 1 Dec 1

[astro-ph/0608390, 1308.1953, 1405.2340]

GF due to Sun produces a %- level annual modulation, with different phase compared to Earth’s orbital speed

Daily modulation amplitude

Similar effect due to focusing from Earth, comparable to effects of Earth’s rotation.

[1505.02615]

Perturb the velocity distribution, perturb the rate!

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Direct Detection Landscape

10−1 100 101 102 103 104

mχ [GeV]

10−48 10−47 10−46 10−45 10−44 10−43 10−42 10−41 10−40 10−39 10−38 10−37 10−36

σSI

p [cm2]

8B

LUX (IDM-2016) CDMSlite (2015) CRESST-II (2015) Xenon1T (2017) Xe Neutrino Floor (O’Hare 2016)

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Direct Detection Landscape

10−1 100 101 102 103 104

mχ [GeV]

10−48 10−47 10−46 10−45 10−44 10−43 10−42 10−41 10−40 10−39 10−38 10−37 10−36

σSI

p [cm2]

8B

LUX (IDM-2016) CDMSlite (2015) CRESST-II (2015) Xenon1T (2017) Xe Neutrino Floor (O’Hare 2016)

Sub-GeV DM

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Direct Detection Landscape

10−1 100 101 102 103 104

mχ [GeV]

10−48 10−47 10−46 10−45 10−44 10−43 10−42 10−41 10−40 10−39 10−38 10−37 10−36

σSI

p [cm2]

8B

LUX (IDM-2016) CDMSlite (2015) CRESST-II (2015) Xenon1T (2017) Xe Neutrino Floor (O’Hare 2016)

Sub-GeV DM WIMPzillas

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Earth-Scattering of sub-GeV DM

BJK, Catena, Kouvaris [1611.05453] Emken, Kouvaris, Shoemaker [1702.07750] Emken & Kouvaris [1706.02249]

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

0.1 1 10 100 300

mχ [GeV]

10−46 10−45 10−44 10−43 10−42 10−41 10−40 10−39 10−38 10−37 10−36 10−35 10−34

ρ0.3 σp

SI [cm2]

LUX CRESST-II p = 5 % p = 10% p = 1%

DD Landscape - Sub-GeV DM

CRESST-II [1509.01515] LUX [1608.07648] + many others…

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

0.1 1 10 100 300

mχ [GeV]

10−46 10−45 10−44 10−43 10−42 10−41 10−40 10−39 10−38 10−37 10−36 10−35 10−34

ρ0.3 σp

SI [cm2]

LUX CRESST-II p = 5 % p = 10% p = 1%

DD Landscape - Sub-GeV DM

CRESST-II [1509.01515] LUX [1608.07648] + many others…

Focus on this region

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Direct Detection of DM (in space?)

χ

Detector Unscattered (free) DM: f0(v)

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Direct Detection of DM on Earth

χ

Detector

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Earth-Scattering - Stopping

χ

Detector Previous calculations usually only consider DM stopping:

Kouvaris & Shoemaker [1405.1729,1509.08720] DAMA [1505.05336] Zaharijas & Farrar [astro-ph/0406531]

Slowing/stopping of DM, without changing direction

vi → vf < vi

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Deflection of Dark Matter

χ

How good is the ‘stopping’ approximation?

Nucleus

α

Need to calculate the distribution of the deflection angle :

α

P(cos α) = 1 σ dσ dER dER d cos α For standard SI, we have at low mass But let’s be more general…

dσ dER ∝ const.

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Non-relativistic effective field theory (NREFT) SI SD

O1 = 1 O4 = ~ Sχ · ~ SN

[1008.1591, 1203.3542, 1308.6288, 1505.03117]

Write down all possible non-relativistic (NR) WIMP-nucleon operators which can mediate the elastic scattering.

[Fan et al - 1008.1591, Fitzpatrick et al. - 1203.3542] See also Riccardo Catena’s talk for more details…

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Non-relativistic effective field theory (NREFT)

O1 = 1 O3 = i~ SN · (~ q × ~ v⊥)/mN O4 = ~ Sχ · ~ SN O5 = i~ Sχ · (~ q × ~ v⊥)/mN O6 = (~ Sχ · ~ q)(~ SN · ~ q)/m2

N

O7 = ~ SN · ~ v⊥ O8 = ~ Sχ · ~ v⊥ O9 = i~ Sχ · (~ SN × ~ q)/mN O10 = i~ SN · ~ q/mN O11 = i~ Sχ · ~ q/mN

SI SD

O12 = ~ Sχ · (~ SN × ~ v⊥) O13 = i(~ Sχ · ~ v⊥)(~ SN · ~ q)/mN O14 = i(~ Sχ · ~ q)(~ SN · ~ v⊥)/mN O15 = −(~ Sχ · ~ q)((~ SN × ~ v⊥) · ~ q/m2

N

. . . Write down all possible non-relativistic (NR) WIMP-nucleon operators which can mediate the elastic scattering.

[Fan et al - 1008.1591, Fitzpatrick et al. - 1203.3542]

  • v⊥ =

v +

  • q

2µχN

  • q

Recoil momentum

[1008.1591, 1203.3542, 1308.6288, 1505.03117] See also Riccardo Catena’s talk for more details…

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Energy spectra

Standard SI/SD int.

mχ = 100 GeV

dσ dER ∼ 1/v2

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Energy spectra mχ = 100 GeV

dσ dER ∼ v2

⊥/v2

dσ dER ∼ q2/v2

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

DM deflection distribution

P(cos α) = 1 σ dσ dER dER d cos α

  • α

(α)

  • χ =
  • α

(α)

  • χ =

Forward Backward Standard SI interaction

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Earth-Scattering - Attenuation

χ

Detector

f(v) → f0(v) − fA(v)

Attenuation of DM flux: Forget slowing and think instead about attenuation:

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Earth-Scattering - Deflection

χ

Detector

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

[1702.07750, 1706.02249] (see later)

Earth-Scattering - Deflection

χ

Collar & Avignone [PLB 275, 1992 and others]

Considered in early Monte Carlo simulations… Can treat (without MC) in the ‘single scatter’ approximation…

λ RE

Assuming DM mean free path As well as more recent ones… Can be very important for light DM. Detector

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

˜ f(v) = f0(v) − fA(v) + fD(v) Earth-Scattering

Total DM velocity distribution:

χ

altered flux, daily modulation, directionality…

λ RE

Assuming DM mean free path Consider both attenuation and deflection in an analytic framework (‘Single scatter’) Consider non-standard DM-nucleon interactions (e.g. NREFT) Detector

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

deff,i = 1 ¯ ni

  • AB

ni(r)dl ¯ λi(v)−1 = ¯ ni σ(v)

Attenuation

Detector

A B

v = (v, cos θ, φ) f0(v) − fA(v) = f0(v) exp

  • −

species

  • i

deff,i(cos θ) ¯ λi(v)

  • Sum over 8 most abundant elements in the Earth: O, Si, Mg, Fe, Ca, Na, S, Al
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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Effective Earth-crossing distance

Most scattering comes from Oxygen (in the mantle) and Iron (in the core)

0.0 0.2 0.4 0.6 0.8 1.0 r/RE 0.0 0.5 1.0 1.5 2.0 n(r) [cm−3] ×1023

Oxygen Iron

NB: little Earth-scattering for spin-dependent interactions

π/4 π/2 θ 0.0 0.2 0.4 0.6 0.8 1.0 1.2 ¯ n deff(θ) [cm−2] ×1032

Oxygen Iron

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Deflection

v = (v, cos θ, φ)

Detector

A B C

v = (v, cos θ, φ) ¯ λi(v)−1 = ¯ ni σ(v)

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Deflection

v = (v, cos θ, φ)

Detector

A B C

v = (v, cos θ, φ) ¯ λi(v)−1 = ¯ ni σ(v) κi = v/v fD(v) =

species

  • i
  • d2ˆ

v deff,i(cos θ) λi(κiv) (κi)4 2π f0(κiv, ˆ v)Pi(cos α)

[Detailed calculation in 1611.05453]

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Deflection

v = (v, cos θ, φ)

Detector

A B C

v = (v, cos θ, φ) ¯ λi(v)−1 = ¯ ni σ(v) κi = v/v fD(v) =

species

  • i
  • d2ˆ

v deff,i(cos θ) λi(κiv) (κi)4 2π f0(κiv, ˆ v)Pi(cos α)

Depends on total cross section Depends on differential cross section

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Deflection

v = (v, cos θ, φ)

Detector

A B C

v = (v, cos θ, φ) ¯ λi(v)−1 = ¯ ni σ(v) κi = v/v fD(v) =

species

  • i
  • d2ˆ

v deff,i(cos θ) λi(κiv) (κi)4 2π f0(κiv, ˆ v)Pi(cos α)

Depends on total cross section Depends on differential cross section

Focus on low mass DM:

mχ = 0.5 GeV

Fix couplings to give 10% probability of scattering in the Earth

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

  • α

(α)

  • χ =

DM deflection distribution

P(cos α) = 1 σ dσ dER dER d cos α O12 = Sχ · ( SN × v⊥) ⇒ d dER ∼ ER v2 O1 = 1 ⇒ dσ dER ∼ 1 v2 O8 = Sχ · v⊥ ⇒ d dER ∼ (1 − mN ER 2µ2

χN v2 )

Forward Backward Standard SI interaction Standard SI interaction

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Deflection

v = (v, cos θ, φ)

Detector

A B C

v = (v, cos θ, φ) ¯ λi(v)−1 = ¯ ni σ(v) κi = v/v fD(v) =

species

  • i
  • d2ˆ

v deff,i(cos θ) λi(κiv) (κi)4 2π f0(κiv, ˆ v)Pi(cos α)

Depends on total cross section Depends on differential cross section

Focus on low mass DM:

mχ = 0.5 GeV

Fix couplings to give 10% probability of scattering in the Earth

Now we have everything we need!

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

EARTHSHADOW Code

EARTHSHADOW code is available online at: github.com/bradkav/EarthShadow Including routines, numerical results, plots and animations…

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 ˜ f(v, γ) [10−3 km/s]

Operator O1 − mχ = 0.5 GeV

Free γ = 0 γ = π/2 γ = π

100 200 300 400 500 600 700 800 v [km/s] 0.7 0.8 0.9 1.0 1.1 ˜ f(v, γ)/f0(v)

Speed Distribution - Operator 1

Detector

Calculate DM speed distribution after Earth scattering: ve ˜ f(v, γ)

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Comparison with Monte-Carlo

http://cp3-origins.dk/site/damascus

Monte-Carlo results from the DaMaSCUS code

[Emken & Kouvaris - 1706.02249]

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Comparison with Monte-Carlo

http://cp3-origins.dk/site/damascus

Monte-Carlo results from the DaMaSCUS code

[Emken & Kouvaris - 1706.02249]

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Speed Distribution - Operator 1

Detector

Calculate DM speed distribution after Earth scattering: ve

100 200 300 400 500 600 700 v [km/s]

π 4 π 2 3π 4

π γ = cos1(hˆ vχi · ˆ rdet)

  • 1 %
  • 10 %
  • 5 %
  • 1 %

1 %

Operator O1 mχ = 0.5 GeV

  • 30%
  • 20%
  • 10%

0% 10% 20% 30%

Percentage change in speed dist. ˜ f(v, γ)

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Speed Distribution - O1 vs O8

Detector

100 200 300 400 500 600 700 v [km/s]

π 4 π 2 3π 4

π γ = cos1(hˆ vχi · ˆ rdet)

  • 1 %
  • 10 %
  • 5 %
  • 1

% 1 %

Operator O1 mχ = 0.5 GeV

  • 30%
  • 20%
  • 10%

0% 10% 20% 30%

100 200 300 400 500 600 700 v [km/s]

π 4 π 2 3π 4

π γ = cos1(hˆ vχi · ˆ rdet)

  • 1 %
  • 2

5 %

  • 10 %
  • 5 %
  • 1 %

1 % 5 %

Operator O8 mχ = 0.5 GeV

  • 30%
  • 20%
  • 10%

0% 10% 20% 30%

Operator 8 - preferentially forward deflection

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Speed Distribution - O1 vs O12

Detector

100 200 300 400 500 600 700 v [km/s]

π 4 π 2 3π 4

π γ = cos1(hˆ vχi · ˆ rdet)

  • 1 %
  • 10 %
  • 5 %
  • 1

% 1 %

Operator O1 mχ = 0.5 GeV

  • 30%
  • 20%
  • 10%

0% 10% 20% 30%

Operator 12 - preferentially backward deflection

100 200 300 400 500 600 700 v [km/s]

π 4 π 2 3π 4

π γ = cos1(hˆ vχi · ˆ rdet)

  • 50 %
  • 25 %
  • 10 %
  • 5

%

  • 1 %

1 % 5 % 1 %

Operator O12 mχ = 0.5 GeV

  • 30%
  • 20%
  • 10%

0% 10% 20% 30%

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 ˜ f(v, γ) [10−3 km/s]

Operator O1 − mχ = 0.5 GeV

Free γ = 0 γ = π/2 γ = π

100 200 300 400 500 600 700 800 v [km/s] 0.7 0.8 0.9 1.0 1.1 ˜ f(v, γ)/f0(v)

Event Rate

Calculate number of signal events in a CRESST-II like experiment, with and without the effects of Earth-Scattering, and . Npert Nfree Scattering predominantly with Oxygen and Calcium. DM particles within of the energy threshold 3 σE Eth ∼ 300 eV Translate the angle into time and detector position

γ

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Mapping the CRESST-II Rate

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Operator 1 - isotropic deflection

LNGS - Operator 1

LNGS - Gran Sasso Lab, Italy

6 12 18 24 time [hours] 0.9 1.0 1.1 1.2 Npert/Nfree LNGS (42.5 N)

  • Atten. only

Atten.+Defl. O1

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Operator 8 - forward deflection

LNGS - Operator 8

LNGS - Gran Sasso Lab, Italy

6 12 18 24 time [hours] 0.9 1.0 1.1 1.2 Npert/Nfree LNGS (42.5 N)

  • Atten. only

Atten.+Defl. O1 O8

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

LNGS - Operator 12

LNGS - Gran Sasso Lab, Italy

6 12 18 24 time [hours] 0.9 1.0 1.1 1.2 Npert/Nfree LNGS (42.5 N)

  • Atten. only

Atten.+Defl. O1 O8 O12

Operator 12 - backward deflection

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Operator 1 - isotropic deflection

6 12 18 24 time [hours] 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 Npert/Nfree SUPL (37.1 S)

O1 O8 O12

SUPL - Operator 1

SUPL - Stawell Underground Physics Lab, Australia

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Around the world

6 12 18 24 time [hours] 0.9 1.0 1.1 1.2 Npert/Nfree LNGS (42.5 N)

  • Atten. only

Atten.+Defl. O1 O8 O12

6 12 18 24 time [hours] 0.9 1.0 1.1 1.2 Npert/Nfree CJPL (28.2 N)

O1 O8 O12

6 12 18 24 time [hours] 0.8 0.9 1.0 1.1 1.2 Npert/Nfree INO (9.7 N)

O1 O8 O12

6 12 18 24 time [hours] 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 Npert/Nfree SUPL (37.1 S)

O1 O8 O12

India-based Neutrino Observatory China Jinping Lab

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

0.1 1 10 100 300

mχ [GeV]

10−46 10−45 10−44 10−43 10−42 10−41 10−40 10−39 10−38 10−37 10−36 10−35 10−34

ρ0.3 σp

SI [cm2]

LUX CRESST-II p = 50% p = 10% p = 1%

Beyond ‘single-scatter’

Emken & Kouvaris [1706.02249]

To go beyond the ‘single-scatter’ approximation, we need a Monte Carlo simulation… DAMASCUS: HTTP://CP3-ORIGINS.DK/SITE/DAMASCUS

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

DaMaSCUS

DM comes from above DM comes from below

Large O(1) daily modulation if DM scatters ~50 times during Earth-crossing

Emken & Kouvaris [1706.02249]

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Implications of Earth-Scattering for light DM

Smoking gun signature: daily modulation + location dependence could confirm DM nature Possibility to distinguish different interactions with different amplitude and phase of modulation

6 12 18 24 time [hours] 0.9 1.0 1.1 1.2 Npert/Nfree LNGS (42.5 N)

  • Atten. only

Atten.+Defl. O1 O8 O12

BJK, Catena & Kouvaris [1611.05453]

Possibility to measure the local DM density (by breaking degeneracy with cross section)

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

DM-Electron scattering + Monte Carlo

Emken, Kouvaris & Shoemaker [1702.07750]

Consider energy loses for very strongly-interacting light DM Bounds on MeV Dark Matter are cut off above some critical cross section: DM lose too much energy and fall below threshold

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

WIMPzillas!

PRELIMINARY

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Direct Detection Landscape - zoomed out

Mack, Beacom & Bertone [0705.4298] Albuquerque & Baudis [astro-ph/0301188]

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Direct Detection Landscape - zoomed out

Mack, Beacom & Bertone [0705.4298] Albuquerque & Baudis [astro-ph/0301188]

Earth’s heat flow from DM capture + annihilation

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Direct Detection Landscape - zoomed out

Mack, Beacom & Bertone [0705.4298] Albuquerque & Baudis [astro-ph/0301188]

Assume e.g. asymmetric DM: no heat flux from annihilation

Focus on this region

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Luckily, deflection of DM can be neglected: angle of deflection (per scatter) goes as .

Earth-scattering for super-heavy DM mA/mχ 1

Consider only stopping/slowing of the DM particles! Large cross section means huge number of scattering events (>>100) Monte Carlo may not be the most efficient tool Need to calculate as a function of ….

vf vi

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Nuclear Stopping Equation

‘Correction factor’ due to nuclear form factors

Solve numerically for a given initial speed and incoming direction (which affects how much of the Earth has to be crossed) dv dx = 1 mχv

species

  • i

ni(r)σi(v)ERi = vσSI

p species

  • i

ni(r) mi mχ

  • A4

i Ci(v)

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Journey to the centre of the Earth

Detector Shielding Earth Atmosphere

χ

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Stopping power

Consider a detector at a depth of 10.6m, with DM particles coming from directly overhead:

CDMS I at the Stanford Underground Facility [astro-ph/0203500]

Atmosphere Earth Shielding

mχ = 105 GeV σp = 10−28 cm2

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Speed Distribution

10 keV CDMS I threshold

mχ = 105 GeV

˜ f(vf) = f0(vi) vi vf 2 dvi dvf

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Preliminary Results

Mack, Beacom & Bertone [0705.4298] Albuquerque & Baudis [astro-ph/0301188]

Possible gain of about 2 orders of magnitude in cross section Caveat: Need to perform full rate calculation, taking into account time variation

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Summary

Experiments are currently exploring the Earth-Scattering regime! Need careful calculations + Monte Carlo to explore signatures Sub-GeV DM: Smoking gun modulation signature May help us distinguish DM-nucleon interactions Could allow us to measure local DM density WIMPzillas: Strongly interacting particles are stopped Old experiments may actually rule out interesting parameter space

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Bradley J Kavanagh (LPTHE, Paris) DM Signatures - 12th June 2017 Earth-scattering of DM

Direct Detection Landscape

10−1 100 101 102 103 104

mχ [GeV]

10−48 10−47 10−46 10−45 10−44 10−43 10−42 10−41 10−40 10−39 10−38 10−37 10−36

σSI

p [cm2]

8B

LUX (IDM-2016) CDMSlite (2015) CRESST-II (2015) Xenon1T (2017) Xe Neutrino Floor (O’Hare 2016)

Sub-GeV DM WIMPzillas Interesting parts of the landscape where Earth-scattering soon to be explored…