Singlet Dark Matter, Type II Seesaw and Cosmic Ray Signals Nobuchika Okada Miami 2009 @ Fort Fauderdale, Dec. 15-20, 2009 University of Alabama, Tuscaloosa In collaboration with Ilia Gogoladze (University of Delaware) Qaisar Shafi (University of Delaware) Toshifumi Yamada (KEK, Japan) Ref: Gogoladze, N.O. and Shafi, “Type II Seesaw and the PAMELA/ATIC Signals, ” PLB 679 (2009) 237 Gogoladze, N.O. ,Shafi, and Yamada, in preparation
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Singlet Dark Matter, Type II Seesaw and Cosmic Ray Signals Nobuchika Okada Miami 2009 @ Fort Fauderdale, Dec. 15-20, 2009 University of Alabama, Tuscaloosa.
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Singlet Dark Matter, Type II Seesaw and Cosmic Ray Signals
Nobuchika Okada
Miami 2009 @ Fort Fauderdale, Dec. 15-20, 2009
University of Alabama, Tuscaloosa
In collaboration with Ilia Gogoladze (University of Delaware) Qaisar Shafi (University of Delaware) Toshifumi Yamada (KEK, Japan)
Ref: Gogoladze, N.O. and Shafi, “Type II Seesaw and the PAMELA/ATIC Signals, ” PLB 679 (2009) 237 Gogoladze, N.O. ,Shafi, and Yamada, in preparation
1. Introduction
Existence of Dark Matter has been established!
Wilkinson Microwave Anisotropy Probe (WMAP) satellite has established the energy budget of the present Universe with a great accuracy
Dark Matter particle: non-baryonic electric charge neutral (quasi) stable
The property of the DM is still a prime open question in particle physics and cosmology
Weakly Interacting Massive Particles (WIMPs) are among the best motivated classes of candidates for the dark matter No candidate in the SM New Physics beyond the SM
What is the scale of WIMP?
TeV scale New Physics is suitable for WIMP DM physics!
Solving the Boltzmann Equation,
Investigating the nature of Dark Matter
Collider Physics (LHC, ILC,…)
Producing DM particles at colliders and measure DM properties mass, couplings with SM particles, spin, etc.
Direct detection of DMA variety of experiments has been carried out to directly detect dark matter particle through its elastic scattering off a nucleon
nucleon
detector
DM underground
cosmic rays originating from DM pair annihilations in the halo associated with our galaxy, sun, …
Indirect detection of DM
Sun
Halo
Sun
DM
DM
Earth
Cosmic-ray
Many experiments:
HEAT, PAMELA, ATIC, PPB-BETS, Fermi-LAT
HESS, MAGIC, EGRET, Fermi-GLAST
Super-K, IceCube
Recent hot topic: cosmic-ray e+/e- excesses
(1) The PAMELA experiment has reported a significant positron excess over the expected background without a corresponding increase in the flux of anti-protons! Adriani et al., Nature 458, (2009) 607
Positron excess
Expected
Solar activity
Expected
(2) Fermi satellite experiment also shows an excess of the sum of cosmic-ray e+ and e- flux
PAMELA and Fermi data may constitute the first indirect evidence of dark matter pair annihilations in the halo!
Puzzle: excess of cosmic-ray e+/e- fluxes
no excess of cosmic-ray anti-proton flux
DM
DM
leptons
DM
DM
quarks
favored? disfavored?
In normal dark matter models, there is no significant difference
This implies a leptophilic nature of DM
Plan of this talk
1. Introduction 2. Propose a simple model of leptophilic DM
3. Numerical analysis Fitting to PAMELA and Fermi data and implication to neutrino
physics
4. Summary
2. Simple model of leptophilic dark matter
What’s missing in the SM?
1. Dark Matter particle we’ve already discussed
2. Neutrino masses and mixings
Oscillation data
Very small mass scaleLarge mixing angle
Simplest extension of the SM to incorporate Dark Matter particle & Neutrino Masses
Introduce 2 scalars
Gogolzdze, N.O. & Shafi, PLB 679 (2009) 237
Neutrino mass via Type II seesaw
DM relic abundance
When , we get the right DM abundance
Leptophilic nature of DM
If is small, dominates
When DM pair annihilations happen in the halo, they produce mostly lepton flux
The flavor structure of the primary lepton fluxes are determined by the Yukawa coupling and hence, there is a correlation with neutrino oscillation data
Interesting Implications
Flavor structure of lepton flux carry the information of neutrino mass matrix:
Cosmic-ray neutrino flux
would be detected in future experiments
(ex: IceCube)
3. Numerical Analysis
We will show the proposed model can fit PAMELA and Fermi data with a suitable choice of parameters
For data fitting, it is necessary to introduce a boost factor (BF~1000) to enhance the annihilation cross section of DMs in the halo
DM relic abundance:
Typical scale to fit PAMELA data:
BF could either have astrophysical origin: large inhomogeneities in DM distribution a particle physics origin: Breit-Wigner enhancement
New scalar S Arrange
Gogolzadze, N.O., Shafi, and Yamada in preparation
In our analysis, free parameters in the model are: DM mass Annihilation cross section (with BF) Triplet scalar mass Yukawa coupling
For simplicity, we consider two cases for triplet scalar mass
(1) triplets from DM annihilation almost at rest
(2) highly boosted triplets
Energy distribution of primary leptons from triplet decay
(1)
(2)
In type II seesaw,
For simplicity, we assume hierarchical neutrino mass spectrum
From the formula of partial decay width and the neutrino oscillation data, we find the flavor structure of primary leptons as
(i) Normal hierarchical case e : mu : tau = 0.02 : 1 : 1 e : mu : tau = 2 : 1 : 1 (ii) Inverted hierarchical case
We calculate cosmic-ray e+/e- flux from DM pair annihilation for various values of DM mass with the annihilation cross section with the boost factor being a free parameter and fit the PAMELA and Fermi data
Positron and electron propagation in the galaxy is determined by the static diffusion equation
Diffusion coef. Energy loss rate Source term
Background flux:
Best fits to PAMELA and Fermi data
(A) NH &
(B) NH &
(C) IH &
Upper bound on neutrino flux from galactic center by Super-K
DM pair annihilations produce neutrino flux directly or via the decay of mu and tau
SuperK measured the up-ward muon flux induced by cosmic-ray muon neutrinos gives us the upper bound on neutrino flux from galactic center
Earth
SK
Neutrinos from GC
Neutrino flux vs. SK upper bound
Flux highly depend on DM density profile around the GC
We consider two typical DM density profiles: NFW profile & isothermal profile with 4 kps core
(A) NH & (B) NH &
Too much flux Too much flux
(C) IH &
Inverted hierarchical case is consistent with SK bound
IceCube+DeepCore experiment can significantly improve the SK bound in the near future
Mandal et al., arXiv:0911.5188 [hep-ph]
5. Summary
We have proposed a very simple extension of the SM to incorporate the DM particle and neutrino masses in the SM, where only one gauge singlet scalar and one SU(2) triplet scalar with a unit hypercharge are introduced.
Neutrino masses are obtained by type II seesaw
The type II seesaw structure naturally induces a leptophilic nature for the DM
The flavor structure of the primary lepton fluxes are related to neutrino oscillation data because of type II seesaw
We have calculated cosmic-ray e+/e- fluxes for two typical masses, and , and for NH and IH neutrino mass spectrum
We have shown that a suitable choice of mass and annihilation cross section (with the boost factor) can fit both PAMELA and Fermi data
We have also calculated neutrino flux form GC and found that NH cases predict too much flux which is severely constrained by Super-K up-ward muon flux
On the other hand, IH case with DM mass 1 TeV and can give a very nice fits to both the PAMELA and Fermi data without tension with the SK bound, and IH neutrino mass spectrum is favored