Transcript PowerPoint プレゼンテーション - Cosmic

High Energy Cosmic Rays
from Decaying Supersymmetric Dark Matter
Koji Ishiwata
(Tohoku University)
In collaboration with
Shigeki Matsumoto (Toyama University)
Takeo Moroi (Tohoku University)
Based on arXiv:0811.0250(hep-ph),0811.4492(astro-ph),
0903.0242(hep-ph)
ICRR, May 8, 2009
1. Introduction
Dark Matter (DM)
 Very weakly interacting with other particles
 Massive
 Stable
It accounts for 23 % of total energy density in the Universe
[WMAP]
In the standard model of particle physics, however,
there is no candidate for DM
Beyond the standard model
Supersymmetry (SUSY) is promising model
Motivated by
 Hierarchy problem
 Gauge coupling unification, etc…
 Lightest superparticle (LSP) is viable candidate for DM
under -parity
As LSP,
 Lightest neutralino (Bino, Wino, Higgsinos mixed state)
 Sneutrino
 Gravitino
LSP-DM scenarios has been studied in cosmological
and astrophysical points of view
 Production processes in thermal history (thermal relic for
lightest neutralino, thermal scattering for gravitino, etc…)
 Consistency with big-bang neucleosynthesis (BBN)
[Kawasaki,Kohri,Moroi]
 Direct detection of DM [DAMA,CDMS-II,XENON10]
 Indirect search via cosmic rays
Signal from DM might be detected [HEAT,EGRET, etc]
Recently, PAMELA (and Fermi) observations have
indicated anomalous fluxes in cosmic-ray
[Adriani et al.]
[Abdo et al.; Chang et al.]
Possible candidates for the origins of the anomalies
 DM annihilation
 DM decay
[Cirelli,Kodastik,Raidal,Strumia; Hisano,Kawasaki,
Kohri,Moroi,Nakayama,etc…]
[Chen,Nojiri,Takahashi,Yanagida; Hamaguchi,Nakamura,
Shirai,etc…]
 Pulsars [Hooper,Blasi,Serpico]
Especially in SUSY, decaying LSP-DM under very weak
-parity violation (RPV) has interesting aspects
 Lifetime can be much longer than the age of the Universe
 PAMELA anomaly can be well reproduced [KI,Matsumoto,Moroi]
Our works
Focusing on decaying LSP-DM scenarios, we calculate
cosmic-ray
and found that
 The PAMELA anomaly can be well explained
 Constraints from cosmic-ray anti-proton observation are
not so severe
 Synchrotron radiation from Galactic center is consistent
with foreground emission observed by WMAP
DM
Cosmic rays
now
time
Contents of my talk
1. Introduction
2. Decaying DM Scenarios
3. Cosmic rays (
)
4. Summary
2. Decaying DM Scenarios
Decaying LSP DM in RPV
LSP
 Gravitino
 Bino
 Sneutrino
RPV
 Bi-linear (Gaugino/Higgsino – lepton mixing)
 Leptonic tri-linear (lepton – lepton – slepton mixing)
Leptonic decay is main mode
Gravitino LSP
[Takayama,Yamaguchi;Buchmuller,Covi,Hamaguchi,Ibarra,
Yanagida]
 Advantage for thermal leptogenesis without conflicting
BBN ( NLSP decays before BBN)
 Cosmic-ray
produced by the
decay explain
EGRET and HEAT simultaneously when
[KI,Matsumoto,Moroi; Ibarra,Tran]
Main mode:
(under bi-linear RPV)
Gravitino
NLSP
Cosmic rays
SM
BBN
now
time
Sneutrino LSP

(not excluded by direct detection experiment)

(with purely Dirac type neutrino mass)
[Hall,Moroi,Murayama]
[Asaka,KI,Moroi]
Main mode:
Thermal relic
NLSP llate decay
Decay in thermal bath
(under tri-linear RPV)
Sneutrino
Cosmic rays
now
time
Bino LSP
 Thermal relic explains DM abundance (one of the most
popular scenarios)
Main mode:
(under tri-linear RPV)
(under bi-linear RPV)
The same as
LSP
Bino
Thermal relic
Cosmic rays
now
time
Decay vs. Annihilation
Production rate
 Decay
Parameters:
 Annihilation
Parameters:
3. Cosmic rays (
)
Propagation of Cosmic rays in the Galaxy
Mean free path
Solve diffusion equation in the Galaxy
Sum up the contributions of inside and outside
of the Galaxy
DM origin flux:
flux
Diffusion equation:
•
•
•
: Diffusion coefficient
: Energy loss rate
:
source term
Solar system
“Diffusion zone”
:speed of light
Note: background (BG) is the astrophysical origin flux
[Moskalenko,Strong], [Baltz,Edsjo]
flux
Diffusion equation:
•
•
: Convection velocity
: pair annihilation rate (
:half height of Galactic disc )
: velocity of
Solar system
“Diffusion zone”
Propagation models:
[Delahaye,Lineros,Donato,Fornengo,Salati]
[Tan,Ng; Protheroe]
Parameter
M1
MED
M2
MAX
MED
MIN
-ray flux
 Cosmological distance
 Milky Way halo
l.o.s.
NFW profile
: DM energy density (NFW)
: -ray energy distribution from single DM decay
Note: for BG flux, we interpolate from lower energy data as,
Numerical Results
 Gravitino LSP
PAMELA anomaly can be well explained when
irrespective of
and final state lepton
PAMELA best-fit value
Electron + Positron Flux
PPB-BETS [Torii et al.]
Fermi
Final state lepton: electron case may be excluded
The other cases may be severely constrained
PAMELA best-fit value
Anti-proton Flux
BESS [Orito et al.; Asaoka et al.; Abe et al.]
CAPRICE[Boezio et al.]
Constraints from anti-proton flux observations may not be
so severe in the decaying gravitino scenario
PAMELA best-fit value
Gamma-ray Flux
EGRET
[Sreekumar et al.]
Consistent with EGRET irrespective of
 Sneutrino LSP
,
PAMELA anomaly
Fermi
irrespective of
Severely constrained, except for final
state:
 Bino LSP
,
PAMELA anomaly
Fermi
irrespective of
Severely constrained, except for final
state leptons are only
On the other hand,
induces synchrotron radiation
under the magnetic field in the Galaxy
!!! Image of synchrotron radiation
In the frequency band, remnant flux of
from
the Galactic center, which is called "WMAP Haze", is reported
[Hooper,Finkbeiner,Dobler]
Numerical Results
Solar system
Synchrotron Radiation Flux
Side view of Galaxy
Radiation flux in decaying gravitino-DM scenario is
which is consistent with "WMAP Haze"
,
4. Summary
In decaying LSP-DM scenarios, we calculate cosmic-ray
and found that
When
,
 The PAMELA anomaly can be well explained, while some
cases where hard
are produced may be excluded by Fermi
 Constraints from cosmic-ray anti-proton observation are
not so severe
 Synchrotron radiation flux from Galactic center is consistent
with foreground emission observed by WMAP
Backup
Gravitino decay
Decay widths
(Large contribution of longitudinal mode)
Cosmic-ray Positron Flux
Decay vs. Annihilation
• Positron source term
(Decay)
(Annihilation)
Decay vs. Annihilation
Parameters:
For Wino annihilation case,
Parameters:
Synchrotron Radiation Flux
Formalism
: Synchrotron radiation energy
per unit time and unit frequency
from single electron
l.o.s.
Solar system
Side view of Galaxy
larger
is expected to have a peak at
and suppressed by
in
Numerical Results
• Gravitino DM
Radio flux in decaying gravitino DM scenario is
which is consistent with WMAP Haze
,
Numerical Results
• Final state:
Flux of
DM scenario
(
)
is expected in leptonically decaying
NLSP decay at the LHC
NLSP decay at LHC
In the gravitino DM scenario, NLSP decay can be detected
at the LHC although its decay length is much larger than the
detector size
When
, the number of decaying
NLSP is expected to be
for
cases
[K.I.,Ito,Moroi]
•
-NLSP:
•
-NLSP:
The number of NLSP decay is expected to be
for the wide parameter region in this scenario
Moreover, with the numbers of decaying and total NLSP,
lifetime can be determined when
with statistical
uncertainty 30% [K.I.,Ito,Moroi]
: Number of (decaying/total) NLSP
: Momentum distribution of NLSP
: Decay probability within
In SUSY event,
,which is not sensitive to mass
spectrum [simulated by HERWIG and ISAJET packages], thus
Observables:
NLSP decay at LHC
NLSP decay at LHC
stau
SUSY event simulated by HERWIG package
in minimal gauge mediation (mass spectrum
is given by ISAJET package)