new signals in dark matter detectors · signals in dark matter detectors joachim kopp (based on...

New signals in dark matter detectors

Joachim Kopp(based on work done in collaboration with

Roni Harnik and Pedro Machado, arXiv:1202.6073)

Kaffeepalaver @ MPIK, November 08, 2012

Joachim Kopp New signals in dark matter detectors 1

ν signals in dark matter detectors

Joachim Kopp(based on work done in collaboration with

Roni Harnik and Pedro Machado, arXiv:1202.6073)

Kaffeepalaver @ MPIK, November 08, 2012

Joachim Kopp ν signals in dark matter detectors 2

Outline

1 Direct Dark Matter detection

2 Standard Model neutrino backgrounds in DM detectors

3 Enhanced neutrino scattering from new physics

4 Temporal modulation of ν signals

5 Constraints on hidden photons and sterile neutrinos

6 Conclusions


Outline






6 Conclusions


Direct Dark Matter detectionIdea: A WIMP (Weakly Interacting Massive Particle) can scatteron an atomic nucleus.

t

f

χ

f

χ

Strategy: Look for feeble nuclear recoil

Problem: Many background processes can mimic the signal:Radioactive decaysCosmic raysNeutrinos→ this talk. . .


Direct DM detection — The experimental challenge

background

suppression


Direct detection results — Current status

101 102 10310- 45

10- 44

10- 43

10- 42

10- 41

10- 40

10-39

WIMP mass m Χ @GeV D

WIM

P-

nu

cleo

ncr

oss

sect

ion

ΣSI

@cm2

D

í

Limits: 90%Countours: 90%, 3Σ

v0 = 220 km� s

vesc = 550 km� s

CRESST

CDM

S H lowthr .L

CDMS-II H2009L

Xe-100 H2012L

Xe-

10 H lowthr .L

DAMA Hq ± 10%Lscattering on Na

DAMA Hq ± 10%Lscattering on I

CoGeNT H2011L

updated version of plot from JK Schwetz Zupan 1110.2721see also Freese Lisanti Savage 1209.3339

Assumptions here:

Elastic DM scattering ∝ target mass


Outline






6 Conclusions


Standard Model neutrino backgrounds in DM detectorsSolar neutrinos are a well-known background to future direct DM searches:

see e.g. Gütlein et al. arXiv:1003.5530

dσSM(νN → νN)

dEr=

G2F mNF 2(Er )

2πE2ν

[A2E2

ν + 2AZ (2E2ν (s2

w − 1)− Er mNs2w )

+ 4Z 2(E2ν + s4

w (2E2ν + E2

r − Er (2Eν + mN)) + s2w (Er mN − 2E2

ν ))],




dσSM(νN → νN)

dEr=

G2F mNF 2(Er )

2πE2ν

[A2E2

ν + 2AZ (2E2ν (s2

w − 1)− Er mNs2w )

+ 4Z 2(E2ν + s4

w (2E2ν + E2

r − Er (2Eν + mN)) + s2w (Er mN − 2E2

ν ))],

ææ

æ

ææææææææææææææææææææææææææææææææææ

10-1 100 101 102 103 10410-1410-1310-1210-1110-1010-910-810-710-610-510-410-310-210-1100101102

Erec HkeVL

coun

ts�N

A�k

eV�y

ear

electron recoil

DAMA

Borexino

XENON100 e-

CoGeNT

pp7Be

13N 15Opep

8B17F

hepSM total rateComponents

10-4 10-3 10-2 10-1 100 10110-2

10-1

100

101

102

103

104

105

106

107

108

Erec HkeVL

coun

ts�to

n�ke

V�y

ear

Nuclear recoil - Ge

pp7Be

13N 15Opep

8B

17F

hep

CoGeNT

CDMS-II

SM total rateComponents

Harnik JK Machado 1202.6073




dσSM(νN → νN)

dEr=

G2F mNF 2(Er )

2πE2ν

[A2E2

ν + 2AZ (2E2ν (s2

w − 1)− Er mNs2w )

+ 4Z 2(E2ν + s4

w (2E2ν + E2

r − Er (2Eν + mN)) + s2w (Er mN − 2E2

ν ))],

SM signal will only become sizeable in multi-ton detectors

But: New physics can enhance the rate


Outline






6 Conclusions


Enhanced neutrino scattering from new physicsQuestion:

Can neutrino scattering be relevant already in the current generation ofDM detectors?Can it explain some of the anomalous signals (CoGeNT, DAMA, CRESST)?

Conditions for large scattering cross sections:Large scattering rate at low energies, low scattering rate at high energies

I High-E neutrino scattering well studied experimentally, consistent with SMI Possible realization: Scattering through a light (or massless) force carrier

φ(mφ ≪ 1 GeV)

ν

ν

f

f

Typically also: Existence sterile neutrinosI Active neutrinos in the same SU(2) doublets as charged leptonsI New physics in the charged lepton sector tightly constrained


Light force carriers: MotivationWe know they exist! In particular the photon in electromagnetism.Top-down approaches to particle physics (Grand Unified Theories (GUTs),string theory, . . . ) usually have extra gauge groupsU(1) factors are often left over when gauge symmetries are broken

I Example: SU(2)× U(1)Y → U(1)em

No preferred mass scale for new gauge bosons(depending on BSM symmetry breaking mechanism)Couplings and masses naturally suppressed in extra-dimensional worlds

see talks by Jörg JäckelSlight cosmological preference for extra “radiation” (light particles)

Hamann Hannestad Raffelt Tamborra Wong 1006.5276


Light force carriers: Motivation (2)

L = LSM −14

F ′µνF ′µν − 12εF ′µνFµν

10-24 10-21 10-18 10-15 10-12 10-9 10-6 10-3 110-16

10-14

10-12

10-10

10-8

10-6

10-4

10-210-24 10-21 10-18 10-15 10-12 10-9 10-6 10-3 1

10-16

10-14

10-12

10-10

10-8

10-6

10-4

10-2

Dark Photon Mass MA'HGeVL

Kin

etic

mix

ing

Ε

Fixedtarget

Kinetically Mixed Gauge Boson

Hg-2LΜ

Hg-2Le

U

SN1987A

Atomic PhysicsAtomic Physics

CMB

Glo

bula

rC

lust

ers

Sun�Globular Clusters, energy loss via Νs

Hin models with d 10 keV sterile neutrinosL

Sun

A' capture in SunHpartly allowedL

CASTCMB

LSW

gΝ2 sin22Θ=10-4

gΝ2 sin22Θ=10-12

Borexino Hin models with UH1L'-charged sterile ΝL

Plot from Harnik JK Machado 1202.6073based in part on works by Jaeckel Redondo Ringwald

Lots of open parameter space . . . more on this laterJoachim Kopp ν signals in dark matter detectors 13

Sterile neutrinos: Theoretical motivationStandard Model singlet fermions are a very generic feature of “newphysics” models

I Leftovers of extended gauge multiplets (e.g. GUT multiplets) (typically heavy)I Dark matter (keV . . . TeV or above)

Neutrino–singlet mixing is one of the allowed “portals” between the SMand a hidden sector.SM singlet fermions can live at any mass scaleTypical Lagrangian:

Lmass ⊃ Yν L̄H∗NR + ms ν̄sNR +12

M NcRNR + h.c.

⇒ mass mixing between active and sterile neutrinos


Sterile neutrinos: Experimental motivationSeveral experiments have seen hints for sterile neutrinosin

(_ )ν µ → (_ )

ν e appearance and(_ )ν e → (_ )

ν e disappearance oscillations. . . but tension with other experiments (

(_ )ν µ → (_ )

ν e,(_ )ν e → (_ )

ν e,(_ )ν µ → (_ )

ν µ)

10-4 10- 3 10- 2 10-110-1

100

101

sin 2 2 Θ Μe

Dm

2

LSND + react. + Ga+ MB all channels

null resultsappearance

null resultsdisappearancenull results

combined

99% CL, 2 dof

JK Maltoni Schwetz 1103.4570 and work in progresssee also Giunti Laveder 1107.1452 and 1109.4033; Mention et al. 1101.2755; Karagiorgi et al. 0906.1997 and 1110.3735

appearance: E776, ICARUS, KARMEN (ν̄e), LSND (ν̄e), MiniBooNE (νe, ν̄e), NOMADdisappearance: Atmospheric Neutrinos, CDHS, KARMEN νe–12C, LSND νe–12C,

MiniBooNE (νµ, ν̄µ), MINOS, Reactor Neutrinos, Solar NeutrinosJoachim Kopp ν signals in dark matter detectors 15

... back to ν signals in dark matter detectors

Model 1: Neutrino magnetic momentsAssume neutrinos carry an enhanced magnetic moment(e.g. for composite neutrinos)

Lµν⊃ µν ν̄σαβ∂βAαν , µν,SM = 3.2× 10−19

Cross section large at low energies due to photon propagator ∝ q−2

dσµ(νe→ νe)

dEr= µ2

να

(1Er− 1

Eν

),

10 1 100 101 102 10310 -8

10 -7

10 -6

10 -5

10 -4

10 -3

10 -2

10 -1

100

101

102

Erec keVee

coun

tsNA

keV

eeye

ar

electron recoil

DAMA

Borexino

XENON100 e

CoGeNT

Standard model

A

A ΜΝ = 0.32 x 10-10ΜB

10 -4 10 -3 10 -2 10 -1 100 10110 -2

10 -1

100

101

102

103

104

105

106

107

108

E /rec keVnr

coun

ts/t

on/k

eV

/nr

year

Nuclear recoil – Ge

CoGeNT

CDMS II

A

Standard model

A ΜΝ = 0.32 x 10 -10 ΜB

Harnik JK Machado 1202.6073Joachim Kopp ν signals in dark matter detectors 17

Model 2: A hidden photon + sterile neutrinosIntroduce a hidden photon A′ and a sterile neutrino νs

Related model with gauged U(1)B first discussed in Pospelov 1103.3261detailed studies in Harnik JK Machado 1202:6073 and Pospelov Pradler 1203.0545

νs charged under U(1)′ → direct coupling to A′

SM particles couple to A′ only through kinetic mixing

L ⊃ −14

F ′µνF ′µν − 14

FµνFµν − 12εF ′µνFµν + ν̄s i /∂νs + g′ν̄sγ

µνsA′µ

− (νL)cmνLνL − (νs)cmνsνs − (νL)cmmixνs

A small fraction of solar neutrinos can oscillate into νs

νs scattering cross section in the detector given by

dσA′(νse→ νse)

dEr=

ε2e2g′2me

4πp2ν(M2

A′ + 2Er me)2

[2E2

ν + E2r − 2Er Eν − Er me −m2

ν

]Joachim Kopp ν signals in dark matter detectors 18

Model 2: A hidden photon + sterile neutrinos

æ

æ

æ

æ æææææææææææææææææææææææææææææææææ

10-1 100 101 102 10310-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

101

102

Erec HkeVeeL

coun

ts�N

A�k

eVee

�yea

r

electron recoil

DAMA

Borexino

XENON100 e-

CoGeNT

Standard model

B

C

DA

Line MA¢ gegΝ

A ΜΝ = 0.32 ´ 10-10ΜB

B 10 keV 4 ´ 10-12

C 50 keV 4 ´ 10-12

D 250 keV 6 ´ 10-12

10-4 10-3 10-2 10-1 100 10110-2

10-1

100

101

102

103

104

105

106

107

108

Erec HkeVnrLco

unts

�ton�

keV

nr�y

ear

Nuclear recoil –Ge

CoGeNT

CDMS-II

D

C

B

A

Standard model

Line MA¢ gNgΝ sin2Θ24

A ΜΝ = 0.32 ´ 10-10ΜB activeB 100 MeV 9 ´ 10-8 activeC 100 MeV 8 ´ 10-7 0.02D 10 MeV 10-6 0.02

A: ν magnetic moment A: ν magnetic momentB, C, D: kinetically mixed A′ + sterile νs B: U(1)B−L boson

C: kinetically mixed U(1)′ + sterile νD: U(1)B + sterile ν charged under U(1)Bproposed in Pospelov 1103.3261, details in Pospelov Pradler 1203.0545Enhanced scattering at low Er for light A′

Negligible compared to SM scattering (∼ g4mT /M4W ) at energies probed in dedicated

neutrino experimentsHarnik JK Machado 1202.6073


Heavier sterile neutrinosSterile neutrinos with mass close to a kinematic threshold in the Sun lead todifferent recoil spectra

Example: mνs ∼ 861 keV (energy of solar Be-7 line: 7Be + e− → 7Li + ν)

æ

æ

æ

æ æææææææææææææææææææææææææææææææææ

10-1 100 101 102 10310-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

101

102

Erec HkeVeeL

coun

ts�N

A�k

eVee

�yea

r

electron recoil

DAMA

Borexino

XENON100 e-

CoGeNT

Standard model

Line mΝs allA 860 keV MA¢ = 10 keVB 850 keV ge gΝ sinΘ24 = 10-11

C 700 keV

Plot from Harnik JK Machado 1202.6073


Outline






6 Conclusions


Annual modulation as a “smoking gun” DM signatureAn annually modulation signal is considered very robust evidence for DM.

Freese Frieman Gould 1988

Earth’s velocity relative to the Milky Way’s DM halo is different in summerand in winter

I Expect annually modulating scattering ratesI Low recoil energy, heavy DM: Peak in summer

High recoil energy, light DM: Peak in winter

The DAMA signalI Highly controversial evidence for annual modulation in nuclear or electron

recoils from NaI detectors2-4 keV

Time (day)

Res

idua

ls (

cpd/

kg/k

eV)

DAMA/LIBRA ≈ 250 kg (0.87 ton×yr)

DAMA collaboration, Bernabei et al. 1002.1028







0 200 400 600 800

v @km�sD

ÙdHc

osΘL

vfH

v®L@

A.U

.D

700 720 740 760 780 800

t = Jun 01

t = Sep 01

t = Dec 01

DM scattering rate:

dRdEr∝∫

vmin

d3vf (~v + ~v⊕)

v

vmin =mN + mχ

mNmχ

√Er mN

2



Time (day)

Res

idua

ls (

cpd/

kg/k

eV)











Time (day)

Res

idua

ls (

cpd/

kg/k

eV)




Annual modulation from ellipticity of the Earth orbitEarth–Sun distance is 3.4% larger in summer than in winterThus, the solar neutrino count rate is generically ∼ 7% larger in winterthan in summerThis modulation is opposite to the DAMA modulation . . .. . . but can mimic signals of O(100 GeV) dark matter Freese Frieman Gould 1988


Annual modulation from active–sterile oscillationsFor active–sterile oscillations with oscillation lengths . 1 AU, sterile neutrinoappearance depends on the time of year.

Pospelov 1103.3261, Harnik JK Machado 1202.6073, Pospelov Pradler 1203.0545

This does not require extreme fine-tuningJoachim Kopp ν signals in dark matter detectors 24

More modulation mechanismsSterile neutrino absorption: For strong νs–A′ couplings and not-too-weakA′–SM couplings, sterile neutrino cannot traverse the Earth.→ lower flux at night. And nights are longer in winter.

Earth matter effects: An MSW-type resonance can lead to modified fluxof certain neutrino flavors at night. And nights are longer in winter.Direction-dependent detection efficiencies: If channeling effects arenon-negligible, detection rates depend on the position of the Sun.


More modulation mechanismsSterile neutrino absorption: For strong νs–A′ couplings and not-too-weakA′–SM couplings, sterile neutrino cannot traverse the Earth.→ lower flux at night. And nights are longer in winter.Earth matter effects: An MSW-type resonance can lead to modified fluxof certain neutrino flavors at night. And nights are longer in winter.

Direction-dependent detection efficiencies: If channeling effects arenon-negligible, detection rates depend on the position of the Sun.


More modulation mechanismsSterile neutrino absorption: For strong νs–A′ couplings and not-too-weakA′–SM couplings, sterile neutrino cannot traverse the Earth.→ lower flux at night. And nights are longer in winter.Earth matter effects: An MSW-type resonance can lead to modified fluxof certain neutrino flavors at night. And nights are longer in winter.

I A special case: Oscillation lengths comparable to 2R⊕or ∼ 1 km (thickness of rock overburden)

1 10 100 1000 1040.00

0.05

0.10

0.15

0.20

Distance L travelled in matter @kmD

Fra

ctio

no

fti

me

Solar Ν baselines at Gran Sasso

Winter HOct-MarLSummer HApr-SepL

Direction-dependent detection efficiencies: If channeling effects arenon-negligible, detection rates depend on the position of the Sun.


More modulation mechanismsSterile neutrino absorption: For strong νs–A′ couplings and not-too-weakA′–SM couplings, sterile neutrino cannot traverse the Earth.→ lower flux at night. And nights are longer in winter.Earth matter effects: An MSW-type resonance can lead to modified fluxof certain neutrino flavors at night. And nights are longer in winter.Direction-dependent detection efficiencies: If channeling effects arenon-negligible, detection rates depend on the position of the Sun.


Outline






6 Conclusions


Hidden photons

L ⊃ −14


FµνFµν − 12εF ′µνFµν + ν̄s i /∂νs + g′ν̄sγ

µνsA′µ

10-24 10-21 10-18 10-15 10-12 10-9 10-6 10-3 110-16

10-14

10-12

10-10

10-8

10-6

10-4

10-210-24 10-21 10-18 10-15 10-12 10-9 10-6 10-3 1

10-16

10-14

10-12

10-10

10-8

10-6

10-4

10-2


Kin

etic

mix

ing

Ε

Fixedtarget


Hg-2LΜ

Hg-2Le

U

SN1987A


CMB

Glo

bula

rC

lust

ers



Sun


CASTCMB

LSW

gΝ2 sin22Θ=10-4

gΝ2 sin22Θ=10-12


Constraints from Jaeckel Ringwald 1002.0329, Redondo 0801.1527,Bjorken Essig Schuster Toro 0906.0580, Dent Ferrer Krauss 1201.2683, Harnik JK Machado 1202.6073


Anomalous energy loss in stars and supernovaeA′ bosons can be produced by plasmon oscillations in stars + supernovae

see e.g. Redondo 0801.1527 and references therein

L ⊃ −14


FµνFµν − 12εF ′µνFµν +

12

m2A′A′µA′µ + Aµjµ

= −14


FµνFµν

+12

m2A′A′µA′µ − εm2

A′A′µAµ +12ε2m2

A′AµAµ + Aµjµ

Equations of motion:

(k2gµν − Πµν(k)− ε2m2A′)Aν + εm2

A′A′µ = 0

(k2gµν −m2A′)A′µ + εm2

A′Aµ = 0

(Πµν(k) = polarization tensor, depends on plasma frequency ωP

and on the inverse bremsstrahlung and Compton scattering rates)

Three regimesI Low mA′ : A′ production suppressed by small effective mixing ∼ m4

A′/ω4P

I mA′ ∼ ωP : Resonant A′ productionI High mA′ : Thermal A′ production

Interesting features:

I Resonant enhancement when MA′ ∼ plasmon massI In general: Non-resonant A′ production everywhere in the star

(not just in the outer photosphere)I But: For very large ε, small optical depth even for A′

→ reduced production, weaker limit

Limit based on requirement Pinvisible < Pvisible (P = energy loss rate)




Interesting features:I Resonant enhancement when MA′ ∼ plasmon massI In general: Non-resonant A′ production everywhere in the star


→ reduced production, weaker limitLimit based on requirement Pinvisible < Pvisible (P = energy loss rate)

10-24 10-21 10-18 10-15 10-12 10-9 10-6 10-3 110-16

10-14

10-12

10-10

10-8

10-6

10-4

10-210-24 10-21 10-18 10-15 10-12 10-9 10-6 10-3 1

10-16

10-14

10-12

10-10

10-8

10-6

10-4

10-2


Kin

etic

mix

ing

Ε

Fixedtarget


Hg-2LΜ

Hg-2Le

U

SN1987A


CMB

Glo

bula

rC

lust

ers



Sun


CASTCMB

LSW

gΝ2 sin22Θ=10-4

gΝ2 sin22Θ=10-12





Interesting features:I Resonant enhancement when MA′ ∼ plasmon massI In general: Non-resonant A′ production everywhere in the star


→ reduced production, weaker limitLimit based on requirement Pinvisible < Pvisible (P = energy loss rate)

10-24 10-21 10-18 10-15 10-12 10-9 10-6 10-3 110-16

10-14

10-12

10-10

10-8

10-6

10-4

10-210-24 10-21 10-18 10-15 10-12 10-9 10-6 10-3 1

10-16

10-14

10-12

10-10

10-8

10-6

10-4

10-2


Kin

etic

mix

ing

Ε

Fixedtarget


Hg-2LΜ

Hg-2Le

U

SN1987A


CMB

Glo

bula

rC

lust

ers



Sun


CASTCMB

LSW

gΝ2 sin22Θ=10-4

gΝ2 sin22Θ=10-12


Joachim Kopp ν signals in dark matter detectors 2810-24 10-21 10-18 10-15 10-12 10-9 10-6 10-3 110-16

10-14

10-12

10-10

10-8

10-6

10-4

10-210-24 10-21 10-18 10-15 10-12 10-9 10-6 10-3 1

10-16

10-14

10-12

10-10

10-8

10-6

10-4

10-2


Kin

etic

mix

ing

Ε

Fixedtarget


Hg-2LΜ

Hg-2Le

U

SN1987A


CMB

Glo

bula

rC

lust

ers



Sun


CASTCMB

LSW

gΝ2 sin22Θ=10-4

gΝ2 sin22Θ=10-12


Other constraints (1)

10-24 10-21 10-18 10-15 10-12 10-9 10-6 10-3 110-16

10-14

10-12

10-10

10-8

10-6

10-4

10-210-24 10-21 10-18 10-15 10-12 10-9 10-6 10-3 1

10-16

10-14

10-12

10-10

10-8

10-6

10-4

10-2


Kin

etic

mix

ing

Ε

Fixedtarget


Hg-2LΜ

Hg-2Le

U

SN1987A


CMB

Glo

bula

rC

lust

ers



Sun


CASTCMB

LSW

gΝ2 sin22Θ=10-4

gΝ2 sin22Θ=10-12


Muon and electron g − 2Atomic physics: Test 1/r2 scaling of electromagnetic forceLight shining through wallsFixed target experiments: A′ production in beam dump, decay to SM

I Expect significant improvement from APEX


Other constraints (2)

10-24 10-21 10-18 10-15 10-12 10-9 10-6 10-3 110-16

10-14

10-12

10-10

10-8

10-6

10-4

10-210-24 10-21 10-18 10-15 10-12 10-9 10-6 10-3 1

10-16

10-14

10-12

10-10

10-8

10-6

10-4

10-2


Kin

etic

mix

ing

Ε

Fixedtarget


Hg-2LΜ

Hg-2Le

U

SN1987A


CMB

Glo

bula

rC

lust

ers



Sun


CASTCMB

LSW

gΝ2 sin22Θ=10-4

gΝ2 sin22Θ=10-12


CMB: Distortions to the black body spectrumAxion telescopes (e.g. CAST): Look for A′ from the Sun oscillating to AB-factories: e+e− → A′ + something,A′ detected as /E or via its decay productsIn models with light sterile neutrinos:

I νs production in stars + supernovaeI νse scattering in Borexino


Outline






6 Conclusions


ConclusionsNeutrino detection and DM detection are closely related(experimentally and theoretically)Low-E solar neutrino spectrum only accessible in DM detectorsWell-motivated new physics could show up at low E .Models with hidden photons and sterile neutrinos can lead to interestingphenomena in dark matter detectors

I Enhanced neutrino–electron scatteringI Enhanced neutrino–nucleus scatteringI Possibility of annual and daily modulation


Thank you!

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