A new mechanism for large boost factor from DM conversions

Yu-Feng Zhou

collaborators:Ze-Peng Liu, Yue-Liang Wu

Institute of theoretical physics (ITP),Chinese Academy of Sciences (CAS).

work in progress

Outline

Introduction The recent DM search results and implications The stability of DM and the CP symmetry The boost factor problem A new source of boost factor from late time DM

conversions Numerical results and simple models Summary

Evidences of DM from gravitational effects

Gravitational curves

Strong lensing

Weak lensing

Large scale structure

CMB

Bullet cluster

Searching for non-gravitational effects

Satellite

underground

Cherenkov telescope balloon

collider

Hint of DM ? Positron fraction

if interpreted as DM signal Large annihilation cross section now, boost

factor problem. Sommerfeld enhancement ? Resonance enhancement ? Non-thermal DM ? DM may slightly decay ?

Mainly annihilation/decay into leptons,

not quarks Light final states <1GeV ? Leptophilic interaction ?

background

PAMELANature 458, 607 (2009)

Hint of DM? electrons plus positrons

ATIC/PPB-BETS Excess in the total flux peak at ~600 GeV rapid drop below 800GeV

Fermi LAT Spectrum harder than

expected background with power index around ~3.

Large boost factor still needed

Nature, 456, 2008,362-365

Phys.Rev.Lett.102:181101,2009

Under ground experiments

J. Li’s Talk

CDMS-II, arXiv:0912.3592

CoGeNT, arXiv:1002.4703,

Xenon100, arXiv:1005.0380

DAMA

CDMS-II

CoGent

Hint on light DM ?

Symmetries important for keeping particle stableelectron:U(1) em. symmetry, lightest charged particle

proton: U(1) B-L symmetry, lightest baryon

DM are often protected by symmetriesWell known examples

SUSY: R-parity,

UED: KK-parity,

Little Higgs: T-parity

Symmetries for DM stability

DM in minimal extensions of the SM

SM Scalar DM

Simplest extension to SM: scalar DM

Silveira, Zee, 1985

McDondald, 1994,

Burgess, Pospelov & Veldhuis, 2001

Barger,Langacker, KcCaskey, 2007

Shafi, Okada, 2009

He,Li, Tsai, 2007,2009

Left-Right Model Scalar DM

P and CP symmetry

Extension to LRM with scalar DM

P and CP broken

auto stable !

Guo, Wang, Wu, YFZ, Zhuang,PRD79,055015(2009);

A LR model with spontaneous P and CP violation

Gauge interaction:

P- and CP-transformations

Flavor contents

Two bi-doublet required for

spontaneous CP violation.

Only one bi-doublet cannot give

the correct CP phase

If P and CP are only broken spontaneously

After EWSB S_D does not participate gauge

Interactions, as it is gauge

singlet Require that S_D does not develop a

nonzero VEV S_D a DM particle

Relic density and direct detection

Parameter space from relic density

Prediction for direct detection

rate one bi-doublet case two bi-doublet case

Guo, Wang, Wu, YFZ, Zhuang,PRD79,055015(2009);

A special case: large Yukawa couplings to light quarks

• Relic density is dominated by heavy quark, not light ones• DM-nucleus scattering is sensitive to light quark Yukawa couplings

DM decay through soft C-breaking terms

Including soft C-breaking term

Guo, Wu, YFZ, PRD81,075014 (2010)

dominant part: C- and P-even

tiny part: C-odd

Explain PAMELA data well. for all type of lepton final

states. mu/tau final states favored by Fermi tau-lepton final states predict High neutrino-induced mu

on flux.

PAMELA

Fermi

Guo, Wu, YFZ, PRD81,075014 (2010)mass parameters

Consider 3 cases with final states dominated by different lepton flavor

Predictions for up-going muon flux

Triplets couple to neutrinos and charged-leptons with the same strength

up-going muon flux can reach the current SK bound

Guo, Wu, YFZ, PRD81,075014 (2010)

Inverse Compton scattering (ICS)

Final state radiation (FSI)

Virtual internal bremsstrahlung (VIB)

ICS

FSIVIB

ICS

FSI

VIB

Diffuse gamma-rays

SH-III caseLH-III case

Guo, Wu, YFZ, PRD81,075014 (2010)

ICSICSFSIFSI

VIBVIB

The boost factor problem

The std. WIMP annihilation

cross section is too small to

account for the PAMELA/Fermi data

Positron flux Boost factor

Bergstrom, Edsjo, Zaharijas, PRL103,031103,09’

Boot factor for DM annihilation Local clumps

Via Lactea II: in subhalo? B~ 4-15, Temperature-dependent ann. cross section

Sommerfeld enhancement

Resonance enhancement

Possible origins of boost factor

Diemand, et al, 0805.1244, Nature

Sommerfeld, Ann. Phy 403, 257 (1931).

J. Hisano, S. Matsumoto and M. M. Nojiri, Phys. Rev. D 67 (2003) Phys. Rev. Lett. 92, 031303 (2004)

Feldman, Liu, Nath, 09Ibe, Murayama, Yanagida, 09

Guo, Wu, 09

Other mechanism: DM decay, non-thermal DM ….

Constraints from relic density

Other constraints

•Halo shape

•CMB, protohalo

Refined analysis at freeze-out

• Cut-off of resonance, recoupling• Force-carrier production & decay rates• Kinetic decoupling

• Self-interaction efficiency, non-thermality

J. Zavala, M. Vogelsberger and S. D. M. White, Phys. Rev. D 81, 083502 (2010)M. Kamionkowski and S. Profumo, Phys. Rev. Lett. 101,261301 (2008)

J. L. Feng, M. Kaplinghat and H. B. Yu, Phys. Rev. Lett. 104, 151301 (2010)arXiv:1005.4678

Boost factor in multi-component DM models(with temperature independent ann. cross sections)

Large boost requires1. Large annihilation cross

section2. Still the correct relic

density

Impossible for one-component thermal DM?

Multi-component DM Models with hidden sectors

naturally have multi-DM DM may have SUSY

partners Neutrinos are already (tiny)

part of DM

boost from simply mixed thermal multi-DM ? (No)

Boost factor from interacting multi-DM ?(Possible)

For thermal relic large cross section Always reduces signal

Thermal evolution of interacting multi-DM

The components can be converted Thermal evolution for interacting DM

Use common variable

Nature of the DM conversion

The role of large Keep the components in chemical equilibrium for a long time

Convert the heavy DM into the light

The total density

The total density at equilibrium

The total density evolves like an ordinary WIMP at early time

Nontrivial z-dependence in effective cross section

The effective cross section

A interesting limit

Approximate form

Two component case

Thermal evolution for two-component DM

1. Thermal equilibrium

2. Departure from thermal equilibrium but still in chemical Equilibrium

3. Late time DM conversion at large z Slow conversion characterized by r(z) Crossing point

4. Freeze-out after Freeze-out condition

Y1(z) increased eventually

The condition for a large boost factor

• Large internal degree of freedom of Y2: • Small mass difference:

• Cross sections satisfy:

Approximate expression for the boost factor

Numerical results

Equilibrium• Equilibrium density Y2

Numerical results

Equilibrium• Equilibrium density Y2• Equilibrium density Y1

Numerical results

Equilibrium• Equilibrium density Y2• Equilibrium density Y1If no conversion• Decoupling of Y2

Numerical results

Equilibrium• Equilibrium density Y2• Equilibrium density Y1If no conversion• Decoupling of Y2• Decoupling of Y1

Numerical results

Equilibrium• Equilibrium density Y2• Equilibrium density Y1If no conversion• Decoupling of Y2• Decoupling of Y1With conversion• Evolution of Y2

Numerical results

Equilibrium• Equilibrium density Y2• Equilibrium density Y1If no conversion• Decoupling of Y2• Decoupling of Y1With conversion• Evolution of Y2• Evolution of Y1

Numerical results

Equilibrium• Equilibrium density Y2• Equilibrium density Y1If no conversion• Decoupling of Y2• Decoupling of Y1With conversion• Evolution of Y2• Evolution of Y1• Evolution of Y1+Y2

Numerical results

B vs mass difference B vs relative cross sections

A generic model

Add to the SM

Cross sections

Parameters and boost factor

Parameter set

(off resonance)

Cross sections

Boost factors

Parameter set

(near resonance)

Summary

In multi-DM models, DM conversion can significantly modify the thermal evolution of each DM component.

The relic density of the DM component may not always inversely proportional to it’s annihilation cross section. Through conversions from heavier DM components, the relic density of light DM can be enhanced, leading to large boost factors.

The boost is mostly temperature independent. For generic models with large conversion rate the boost fact can reach ~100-1000.

Thank You !

backups

Positron signals

Diffusion eq.

Background

Sources from DM decay

The Sommerfeld enhancement

Sommerfeld enhancement factor S:

N. Arkani-Hamed, et al, Phys. Rev. D 79, 015014(2009)

KITPC 2011 programDark matter and new physics Sept. 21-Nov. 06, 2011 (7-week)

International Coordinators: Shafi, Qaisar (Delaware), Aprile, Elena (Columbia U.) Wang, Tsz-king Henry(IOP,) Wefel, John (Louisiana Stat

e U.) Matsumoto, Shigeki (IPMU), Su, Shu-Fang (Arizona U.) Geng, Chao-Qiang ( NCTS ),

Local Coordinators: Bi, Xiao-Jun (IHEP) Ni, Kai-Xuan (SJTU) Yang, Chang-Geng (IHEP) Yue, Qian (Tsinghua U.) Zhou, Yu-Feng (ITP )

Numerical results

B~150 B~1000

no conversion

With conversion

Large boost factor if mass diff. is small

The Sommerfeld effectA. Sommerfeld, Annalen der Physik 403, 257 (1931).

J. Hisano, S. Matsumoto and M. M. Nojiri, Phys. Rev. D 67 (2003) Phys. Rev. Lett. 92, 031303 (2004)

Constraints from relic density

J. L. Feng, M. Kaplinghat and H. B. Yu, Phys. Rev. Lett. 104, 151301 (2010)

Irreducible process

Symmetries for hidden sector DM

Hidden sector U(1) symmetryexact U(1) Broken U(1): a massive Z’, a scalar

Hidden custodial symmetry vector DM

Custodial symmetry SU(2)_C keep vector bosons stable

Ackerman,buckley,Carroll, Kamonkowski 08’Feng, Tu, Yu 08’, Feng, Kaplinghat, Tu, Yu 0

9’Foot etal. 10’

Pospelov, Ritz, voloshin 07’Gpoalakrishnal,Jung,Wells 08’

Gpoalakrishnal,Lee,Wells 08’Mambrini 10’

Higgs portalkinetic mixing

Hambye 08’

SM Hidden sector DM

Symmetry not shared wiht SM sectorSymmetry not shared wiht SM sector