Embed Size (px)
Citation preview
Sergio Palomares-Ruiz
November 17, 2008
Dark Matter Annihilation/Decay
ScenariosNovel Searches for Dark Matter with
Neutrino Telescopes
Columbus, OH (USA) November 17-19, 2008
Sergio Palomares-Ruiz
November 17, 2008
What do we know about Dark Matter?
• Astrophysicist view:
• Particle Physicist view:
Sergio Palomares-Ruiz
November 17, 2008
Sergio Palomares-Ruiz
November 17, 2008
Model-independent bound
• Neutrinos are the least detectable particles of the SM
• From the detection point of view the most conservative assumption (the worst case) is that DM annihilates (decays) only into ν’s:
  → νν ( → νν)
• This is not an assumption about realistic models
• It provides a bound on the total annihilation cross section (lifetime) and not on the partial cross section (lifetime) to neutrinos
• Anything else would produce photons, and hence would lead to a stronger limit
J. F. Beacom, N. F. Bell and G. D. Mack, Phys. Rev. Lett. 99:231301, 2007
Sergio Palomares-Ruiz
November 17, 2008
Two energy regions: backgrounds
Strategy• Calculate neutrino flux
• Compare potential signal with the background
• E ~ 100 MeV – 100 TeV: atmospheric neutrino flux
• E ~ 10 MeV – 100 MeV: invisible muons and atmospheric neutrino flux
Sergio Palomares-Ruiz
November 17, 2008
Signal from Annihilations
annsc
ann
JRdE
dN
mdE
d
202
2
4
Experiment Particle Physics Astrophysics
Sergio Palomares-Ruiz
November 17, 2008 Field of View
Neutrino Spectrum: Flavor democracy
Average of the Line of Sight Integration of ½2
cos12
mEdE
dN
3
2
cos 2)(11 1
cos 0
220
max
ddrR
Jsc
ann
22 cos2 scsc RRr cossin 222max scschalo RRR
Sergio Palomares-Ruiz
November 17, 2008 Signal from Decays
dksc
dk
JRdE
dN
mdE
d
0
1
4
Experiment Particle Physics Astrophysics
Sergio Palomares-Ruiz
November 17, 2008 Field of View
Neutrino Spectrum: Flavor democracy
Average of the Line of Sight Integration of ρ
cos12
2/3
2 mE
dE
dN
cos 2)(11 1
cos 00
max
ddrR
Jsc
dk
22 cos2 scsc RRr
cossin 222max scschalo RRR
/
/1
/1)(
s
sscscsc
rr
rR
r
Rr
Sergio Palomares-Ruiz
November 17, 2008
Annihilations vs Decays
• 2 DM particles
• E = mÂ
• Proportional to <¾v>/mÂ
2
• Proportional to ½2
• 1 DM particle
• E = mÂ/2
• Proportional to 1/¿ÂmÂ
• Proportional to ½
s10
GeV 100
GeV/cm 3.0s/cm10310
26
0
3326 m
dE
d
dE
d anndk
Sergio Palomares-Ruiz
November 17, 2008
DM Density Profile Uncertainties
SPR and S. Pascoli, Phys. Rev. D77:025025, 2008
•Local rotational velocity•Amount of flatness •Non-halo components
P. Belli et al. , Phys.Rev.D 66:043503, 2002
From the allowed range of:
Annihilations:
Decays:
Extreme values for the 3 profiles: Javg = (1.3, 8.1)SPR, Phys. Lett. B665:50, 2008
Sergio Palomares-Ruiz
November 17, 2008
Energy resolution: ¢log E = 0.34
GeV 10
GeV 1030 E
Eo
GeV 10 30 Eo
H. Yüksel, S. Horiuchi, J. F. Beacom and S. Ando, Phys. Rev. D76:123506, 2007
Other related limitsM. Kachelriess and P. D. Serpico, Phys. Rev. D76:063516, 2007N. F. Bell, J. B. Dent, T. D. Jacques and T. J. Weiler, Phys. Rev. D78:083540, 2008J. B. Dent, R. J. Scherrer and T. J. Weiler, arXiv:0806.0370G. D. Mack, T. D. Jacques, J. F. Beacom, N. F. Bell and H. Yüksel, Phys. Rev. D78:063542, 2008
Sergio Palomares-Ruiz
November 17, 2008
Can we do better?
• Careful treatment of energy resolution and backgrounds: eg. limits on MeV DM
• We use SK data for E = 18-82 MeV
• Detection: νe + p → e+ + n
• Two main backgrounds: – Invisible muons– Atmospheric neutrinos
M. S. Malek, Ph.D thesisM. S. Malek et al., Phys. Rev. Lett. 90:061101, 2003
Sergio Palomares-Ruiz
November 17, 2008
Analysis16 4-MeV bins in the range [18,82] MeV
Nl = Number of events in bin lAl = fraction of signal eventsBl = fraction of Michel electrons (positrons)Cl = fraction of atmospheric electron (anti)neutrinos
902
0
2 9.0)( )(
dPeKP
Sergio Palomares-Ruiz
November 17, 2008
We perform a similar Â2 analysis as that done by SK to limit the flux of DSNB and we set an upper bound on the DM annihilation cross section
SPR and S. Pascoli, Phys. Rev. D77:025025, 2008SPR, arXiv:0805.3367
Annihilations:
Sergio Palomares-Ruiz
November 17, 2008
LENA: 50000 m3 scintillator after 10 years
Reactor BG DSNB Atmospheric BGSPR and S. Pascoli, Phys. Rev. D77:025025, 2008
What if this is actually the case and DM only annihilates into neutrinos?
C. Boehm, Y. Farzan, T. Hambye, SPR and S. Pascoli, Phys. Rev. D 77:043516, 2008
Sergio Palomares-Ruiz
November 17, 2008
SPR, Phys. Lett. B665:50, 2008 Model-independent boundfrom CMB observations
K. Ichiki, M. Oguri and K. Takahashi,Phys. Rev. Lett. 93:071302, 2004
GeV 10
GeV 1030 E
Eo
GeV 10 30 Eo
4
Using SK data from DSNB search:Detailed analysis of background and energy resolution
New model-independent boundfrom CMB and SN observationsY. Gong and X. Chen, Phys. Rev. D77:103511, 2008
Decays:
For γ-line limits:H. Yuksel and M. Kistler, Phys. Rev. D78:023502, 2008
Sergio Palomares-Ruiz
November 17, 2008
A few words on PAMELA
O. Adriani et al., arXiv:0810.4994 O. Adriani et al., arXiv:0810.4995
Annihilations: need of large boost factors
Sub-structure Sommerfeld enhancementNon-thermal production
Decays: no need of boost factors -> “short” lifetime
s10
GeV 100
GeV/cm 3.0s/cm10310
26
0
3326 m
dE
d
dE
d anndk
M. Cirelli, M. Kadastik, M. Raidal and A. Strumia,arXiv:0809.2409
Sergio Palomares-Ruiz
November 17, 2008
Conclusions• Neutrino detectors can test DM properties
• Searches for neutrinos from DM annihilations/decays in the galactic halo could constitute powerful probes of DM properties
• Neutrino detectors can set model-independent bounds on the DM annihilation cross section and on the DM lifetime
• Difficult to distinguish annihilation/decay scenarios: use angular information
• Future detectors (LENA) might be able to detect a signal from DM annihilations/decay
Sergio Palomares-Ruiz
November 17, 2008
When you have eliminated all which is impossible,
then whatever remains, however improbable,
must be the truth
Sherlock Holmes
The world is full of obvious things which nobody by any chance ever observes
Long arm looking for a fingerprinttrying to find the mystery clue
Bon Scott
