Indirect searches for dark matter at Baikal

Indirect searches for dark matter at Baikal

Dark Ghosts:

1st GNN Workshop on Indirect Dark Matter Searches Valencia, 10-11 April 2014

S.V.Demidov INR RAS

Neutrino signal from DM annihilations in the Sun

I We use NT-200 as a playground for studing of indirect DM searches technics

I Benchmark channels: b¯b, W⁺W⁻, τ⁺τ⁻,ν_eν¯_e,ν_µν¯_µ,ν_τν¯_τ

I Expected muon neutrino and muon uxes from dark matter annihilation in the Sun

Φ_νµ = Γ_A

4πR² ×X

νj,ν¯j

Z mDM

Eth

dE_νjP_νµ(E_νj,E_th)dNν^prodj

dE_νj Pνµ(Eνj,E_th) - probability to obtain neutrino or muon at the detector level

Baikal Neutrino Telescope (NT200)

I 8 strings and 192 OM

I Angular resolution 4-5^◦

I Energy thresholdE_th≈10GeV

I data from April 1998 to February 2003

I Events towards the Sun

1e-12 1e-10 1e-08 1e-06 0.0001 0.01 1

10 100 1000 10000

Aνeff, m2

E_ν, GeV no Sun track

Sun track

Expected number of events N_µ=RMDM

Eth dE_νdΩA^ν_eff(E_ν,Ω)_dE^d2Nν

νdΩ

Indirect searches for dark matter at Baikal 3

Signal simulation: overview and parameters

I We use our C program; compare results with WIMPsim and PPPC

I Initial neutrino spectra at the center of the Sun: PYTHIA

I Annihilation point near the center of the Sun

I Neutrino oscillations,3×3scheme

I Matter eects: solar model, J.N.Bahcall, A.M.Serenelli½ S.Basu (2005). We should improve here.

I NC and CC interactions (including τ-mass eects) in the Sun and the Earth: change in neutrino uxes and spectra

I ντ regeneration:ντ →τ⁻+...,τ⁻ →ντ,ν¯e,ν¯µ+... - secondary neutrinos

Comparison with WIMPsim: ν

spectra at 1 a.u.

For the same initial neutrino spectra

0.001 0.01 0.1 1 10

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 dNν/dz (ann-1)

z=E_ν/m_DM bb, m_DM = 100 GeV

ν_µ at production WimpSim, ν_µ at 1 a.u.

our calculations, νµ at 1 a.u.

0.001 0.01 0.1 1 10

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 dNν/dz (ann-1)

z=E_ν/m_DM

W⁺W^-, m_DM = 100 GeV ν_µ at production ν_τ at production WimpSim, νµ at 1 a.u.

our calculations, νµ at 1 a.u.

0.001 0.01 0.1 1 10

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 dNν/dz (ann-1)

z=E_ν/m_DM τ⁺τ^-, m_DM = 100 GeV

ν_τ at production ν_µ at production WimpSim, νµ at 1 a.u.

our calculations, νµ at 1 a.u.

0.001 0.01 0.1 1 10

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 dNν/dz (ann-1)

z=E_ν/m_DM

W⁺W^-, m_DM = 1000 GeV ν_µ at production ν_τ at production WimpSim, νµ at 1 a.u.

our calculations, νµ at 1 a.u.

Indirect searches for dark matter at Baikal 5

PPPC 4 DM ν

I New calculation neutrino energy spectra by M.Cirelli, A.Strumia et.al arXiv:1312.6408, JCAP (2014)

I GEANT 4 to simulate propagation of annihilation products in the Sun, in particular eect of secondary products

I EW corrections to spectra: radiation of soft electroweak bosons enhance EW corrections by powers of logM_DM/M_Z

I Neutrino spectra at production and at the Earth are availible for particular solar model and particular oscillation parameters.

PPPC 4 DM ν : comparison with other spectra

0.001 0.01 0.1 1 10

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 dNν/dz (ann-1)

z=E_ν/m_DM bb, mDM = 100 GeV WimpSim, νµ at 1 a.u.

our calculations, νµ at 1 a.u.

EW corrections, ν_µ at 1 a.u.

0.001 0.01 0.1 1 10

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 dNν/dz (ann-1)

z=E_ν/m_DM

W⁺W^-, m_DM = 100 GeV WimpSim, νµ at 1 a.u.

our calculations, ν_µ at 1 a.u.

EW corrections, ν_µ at 1 a.u.

0.001 0.01 0.1 1 10

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 dNν/dz (ann-1)

z=E_ν/m_DM

bb, mDM = 1000 GeV WimpSim, νµ at 1 a.u.

our calculations, νµ at 1 a.u.

EW corrections, ν_µ at 1 a.u.

0.001 0.01 0.1 1 10

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 dNν/dz (ann-1)

z=E_ν/m_DM

W⁺W^-, m_DM = 1000 GeV WimpSim, νµ at 1 a.u.

our calculations, ν_µ at 1 a.u.

EW corrections, ν_µ at 1 a.u.

Indirect searches for dark matter at Baikal 7

Comparison of dierent spectra

Eective areas normalized to those obtain with WimpSim spectra

0 0.5 1 1.5 2 2.5 3

0 100 200 300 400 500 600 700 800 900 1000 Seff/SWSeff

m_DM, GeV bb

our calculations Strumia et.al., 2013

0 0.2 0.4 0.6 0.8 1 1.2

0 100 200 300 400 500 600 700 800 900 1000 Seff/SWSeff

m_DM, GeV τ⁺τ^-

our calculations Strumia et.al., 2013 0

0.2 0.4 0.6 0.8 1 1.2

100 200 300 400 500 600 700 800 900 1000 Seff/SWSeff

m_DM, GeV W⁺W^-

our calculations Strumia et.al., 2013

Considerable corrections! Sensitivity tobb¯ increases, while to W⁺W⁻ decreases!

Muon ux calculation

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

0 5 10 15 20 25 30

dNµ/dγ (1/Nµ)

γ (deg) τ⁺τ^-, mDM = 90 GeV

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07

0 5 10 15 20 25 30

dNµ/dγ (1/Nµ)

γ (deg) bb, mDM = 90 GeV

I Muons are produced in neutrino CC interactions

I Mean muon energy losses in rock (D.E.Groom, N.V.Mokhov, S.I.Striganov, 2001)

h^dE_dxi=−(α(E) +β(E)E)ρ

I Multiple Coulomb scattering

Indirect searches for dark matter at Baikal 9

Neutrino from the Sun and optimization

expected limit on neutrino ux≈ _Aν^N¯90(γ) eff(γ)×T

The eective area for given spectrum A^ν_eff(γ) =

R_mDM

Eth dE_νA(E_ν,E_th)P_µ(E_ν,θ)^dNν(Eν_dEν ⁾ R_mDM

Eth dEνPµ(Eν,θ)^dNν_dEν^(Eν)

Upper limit- using TRolke root class

°) -Sun( Ψµ

0 5 10 15 20 25

Events per bin

0 1 2 3 4 5 6 7

Data Apr_1998 - Feb_2003 years

Measured background Background fit

1e-10 1e-08 1e-06 0.0001 0.01 1

10 100 1000 10000

Aeffν, m2

E_ν or m_DM, GeV bb

W⁺W^- τ⁺τ^- νeνe ν_µν_µ ν_τν_τ total

0 2 4 6 8 10 12

10 100 1000 10000

Ψ (°)

bbτ⁺τ^- W⁺W^-

Upper limits on neutrino ux

Φ^lim_ν = _A^Nν^90(γ)

eff×T, recalculated on E_ν >1GeV;

1e+09 1e+10 1e+11 1e+12 1e+13 1e+14 1e+15 1e+16 1e+17 1e+18

10 100 1000 10000

Φν, km-2 yr-1

m_DM, GeV

Baikal 1998-2003, bb Baikal 1998-2003, W⁺W^- Baikal 1998-2003, τ⁺τ^- Baikal 1998-2003, ν_eν_e Baikal 1998-2003, ν_µν_µ Baikal 1998-2003, ν_τν_τ

Indirect searches for dark matter at Baikal 11

Upper limits on muon neutrino ux

Φ^lim_ν = _A^Nν^90(γ)

eff×T, recalculated on E_ν >1GeV;

1e-08 1e-07 1e-06 1e-05 0.0001 0.001 0.01 0.1 1 10

10 100 1000 10000

Φν, cm-2 s-1

m_DM, GeV

IceCube 2012, hard IceCube 2012, bb ANTARES 2007-2008, W⁺W^- ANTARES 2007-2008, bb ANTARES 2007-2008, τ⁺τ^- Baksan 1978-2009, W⁺W^- Baksan 1978-2009, bb Baksan 1978-2009, τ⁺τ^- Baikal 1998-2003, W⁺W^- (pr.) Baikal 1998-2003, bb (pr.) Baikal 1998-2003, τ⁺τ^- (pr.) Baikal 1998-2003, ν_eν_e (pr.) Baikal 1998-2003, ν_µν_µ (pr.) Baikal 1998-2003, ν_τν_τ (pr.)

Recalculation to upper limits on SD

G. Wikstrom, J. Edsjo, 2009

I Firstly, we recalculateΦµ→ΓA

I In equilibrium between capture and annihilation processes:

ΓA =CDM/2

I Capture rate is determined by the SI and SD elastic cross section of DM particles on nucleons (Gould, 1987)

I Recalculation ΓA→σ^SD_p , σ^SI_p (Olga Suvorova, S.D., 2010)

Γ_A = Γ^SD_A + Γ^SI_A, σ_p^SD

Γ^SD_A ·Γ^Upp.Lim._A =σSD,Upp.Lim.

p , σ_p^SI

Γ^SI_A ·Γ^Upp.Lim._A =σSI,Upp.Lim.

p

I Upper limits on SD cross sections are strong - a lot of hydrogen in the Sun

Indirect searches for dark matter at Baikal 13

Upper limits on SD elastic cross section: indirect searches

1e-40 1e-39 1e-38 1e-37 1e-36 1e-35

10 100 1000 10000

σχpSD, cm2

m_DM, GeV

ANTARES 2007-2008, bb ANTARES 2007-2008, W⁺W^-

ANTARES 2007-2008 τ⁺τ^- Super-K 2011, bb Super-K 2011, W⁺W^-

IceCube 2012, bb IceCube 2012, hard Baksan 1978-2009, bb Baksan 1978-2009, W⁺W^-

Baksan 1978-2009, τ⁺τ^- Baikal 1998-2003, bb Baikal 1998-2003, W⁺W^-

Baikal 1998-2003, τ⁺τ^-

Upper limits on SD: direct and collider searches

1e-40 1e-39 1e-38 1e-37 1e-36 1e-35

10 100 1000 10000

σχpSD, cm2

m_DM, GeV

DAMA no channeling 2008 PICASSO 2012

KIMS 2011 SIMPLE 2011

COUPP 2012 Baikal 1998-2003, bb Baikal 1998-2003, W⁺W^-

Baikal 1998-2003, τ⁺τ^- Baikal 1998-2003, ν_eν_e Baikal 1998-2003, ν_µν_µ

Baikal 1998-2003, ν_τν_τ

Indirect searches for dark matter at Baikal 15

Systematic uncertanties

I Experimental uncertanties NT200:≈30%.

I Inuence of uncertanty in neutrino oscillation parameters on propagation: ≈5% for W⁺W⁻ andb¯b,≈8% for τ⁺τ⁻

I Inuence of neutrino nucleon cross section on propagation in the Sun and the Earth - up to 10% for E_ν ∼10 GeV and 4%

for E_ν ∼1 TeV.

I Contribution of tau-neutrinos to the muon events - around 6%.

I Considerable corrections from new neutrino spectra at production!

I For limits on SD and SI cross sections: astrophysical uncertanties (chemical composition of the Sun, local dark matter density ρχ, DM velocity distribution, ...)

Thank you!

Indirect searches for dark matter at Baikal 17

Comparison of upper limits for W

W

and τ

τ

channels

I Comparable limits on muon uxes

I Number of neutrinos (and antineutrinos) per annihilation:

≈1.0 forW⁺W⁻ and≈2.6 forτ⁺τ⁻

I Eect of oscillations

0 1 2 3 4 5

10 100 1000

Φµ, osc/Φµ, noosc

m_DM, GeV

bb W⁺W^- τ⁺τ^-