Indirect DM Search: Current Status and Report
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Transcript of Indirect DM Search: Current Status and Report
Indirect dark matter searchCurrent status and report
YenHsun Lin (林彥勳 )Nat'l Chiao Tung Univ., Taiwan
江門中微子實驗黃皮書進展研討會8/4~8/9, 廈門
Neutrino flux from DM in the Sun
● The neutrino flux from DM annihilation in the Sun is given by:
● The is related to the DM particle property: σχp, the DM-nucleon cross section
● Spectrum dN/dE can be generated by WimpSim
Total annihilation rate
Neutrino spectrum @ solar core
JCAP 08, 021 (2008)
How evolves?
● The DM number evolution equation in the Sun
● The solution:
Self-interaction Self-interactioninduced evaporation
Gravitational capture Evaporation
Annihilation
Gravitational capture
● DM particles in the Halo attracted by solar gravity therefore scatter with nucleus and captured
● Two types of DM-nucleus interaction: 1) spin-dependent and 2) spin-independent
G
DM capture rate
● Spin-dependent:
● Spin-independent:
Phys.Rept. 267, 195 (1996)Phys.Rept. 405, 279 (2005)
DM capture ratearXiv:1312.6048
σχp
= 1 pb σχp
= 1 pb
Evaporation
● The captured DM particles scattered with the nucleus in the Sun and gains kinetic energy thus escapes
DM evaporation rate
● The evaporation rate:
Ce
σχp
= 10−4 pb
Left is for spin-dependent and spin-independent is similar.
JCAP 07, 010 (2013)
Astrophys. J. 321, 560 (1987)Nucl. Phys. B 283, 681 (1987)
Self-interaction, S.I.
● The Halo DM particles scatter with the DM already captured by the Sun● Both captured
● One captured, the other escapes
● Both escapes (self-eject)
PRD 80, 063501 (2009)
S.I. induced evaporation
● It's not one of the three situations mentioned before
● Explored by no one before as far as we know
DM number inside the Sun
Y.-H. Lin, Talk@ICHEP 2014
Total annihilation rate
● directly matters to the ν signal
● Actually not only related to σχp also σχχ
Y.-H. Lin, Talk@ICHEP 2014
Event rate estimation
● The neutrino event rate can be estimated:
Detector effective area
We used IC-PINGU's to calculate
Detector effective volume ν
e
νμ
arXiv:1401.2046
Mton
Mton
Let's have a look @
● With mχ > 5 GeV, the evaporation mass
● The most popular channels examined are: τ, ν, W...etc.
Hard channel Soft channel
High energy neutrino from annihilation/decay producthighest fewest
C. Rott, Talk@CosPA 2013
Disfavored by current galactic constraints
See review article arXiv:1202.1454 for further details
We expected...
● JUNO detector has ~ 20 kton effective volume
● By examining the hard spectrum
● We can expect the JUNO σχp-sensitivity by projecting the results from PRD 84, 036007 (2011)
Unfortunately...
● Evaporation occurs while ● Current galactic constraints favor leptophillic dominant
channels, but they are not realistic● The JUNO effective volume is not such large @ GeV level ● JUNO detector is designed to have better performance @
MeV level
IceCube JUNO
Effective voume 3-5 Mton <20 kton
Sensitive flavor All
Event rate (yr-1) ~7000 (Cas+Tra) <2
Around Eν ~ GeV
If JUNO is capable running @ GeV constantly all year
Soft spectrum revisited
● So far, the problems raised when we focus on hard spectrum signal● How about soft spectrum? Is it really non-detectable @ detector?
?1 GeV 100 GeV
Soft HardRecently...
MeVPRD 34,2206(1986)Nucl.Phys.B304,877(1987)
Considered as non-detectable
Pion multiplication
HadronsB
f = 64.79%
Goes to hard spectrum
Solar core
Annu.Rev.Nucl.Sci. 23, 395 (1973)
if survives
Continuous hadronic interaction
in the medium and energy lossPion decay at rest
Eν up to 52.8 MeV
Coulomb absorp-tion, no contribu-tion
negligible contribution
Pion
stop
pin
g p
oi n
t
Low energy neutrino from hadronic shower
Pion yieldPion yield at the production point as a function of DM mass m
χ
JCAP 08, 011 (2013)
ν-yield from π multiplication
PRD 88, 055005 (2013)JCAP 08, 011 (2013)
ν-yield @ Solar core
● Taking mχ = 10 GeV to avoid evaporation● Examining spectra from b and τ channels ● Higher mχ is achievable→Severe attenuation happens @ TeV
arXiv:1312.6048
Disadvantage to ICDC
No affect to MeV ν-yield: Advantage to JUNO
ν-yield @ JUNO
● Settings are the same as previous: ν-yield per annihilation
Soft spectrum10 - 100 MeV
Hard spectrum1 - 10 GeV
Hard spectrum1 - 10 GeV
Soft spectrum10 - 100 MeV
arXiv:1312.6048
Event rate re-estimation
● The high ν-yield is now @ MeV range● Thus:
● ν cross section can be approximated as:
● We can estimate the event rate in JUNO per year with (no S.I.):
10 MeV
100 MeV
PRD 60, 053003 (1999)Phys.Lett.B 564, 42 (2003)PRD 88, 055005 (2013)
~0.39 yr-1
Current status
● The soft spectrum has high ν-yield● MeV neutrinos produced via DM-DM annihila-
tion is potentially detectable in JUNO● At MeV energy, JUNO has maximum effective
volume● We estimated the neutrino event rate per year
in JUNO● By the unique spectrum shape, we can further
examine different DM scenarios
Further steps and discussions
● ν cross section is approximated not exactly calculated or from fine MC simulation
● Event rate is just a rough estimation, careful calculation required
● Backgrounds ● Angular/energy resolutions ● Day/night effects ● Manuscript not updated yet!!!● ……● Stay tuned!
Haven't analyzed yet!!!