# Presentation: 513350

## Studying Supersymmetry With Dark Matter

***Dan Hooper***
***Theoretical Astrophysics Group***
***dhooper@fnal.gov***

**Studying Supersymmetry With Dark Matter**

- Fermilab Wine and Cheese Seminar
- September 1, 2006

## Dark Matter

- Evidence from a wide range of astrophysical observations including rotation curves, CMB, lensing, clusters, BBN, SN1a, large scale structure

## NASA/Chandra Press Release, August 21, 2006 

**NASA/Chandra Press Release, August 21, 2006 **

## Dark Matter

- Evidence from a wide range of astrophysical observations including rotation curves, CMB, lensing, clusters, BBN, SN1a, large scale structure
- Each observes dark matter through its gravitational influence
- Still no (reliable) observations of dark matter’s electroweak interactions (or other non-gravitational interactions)
- Still no (reliable) indications of dark matter’s particle nature

## The Dark Matter Candidate Zoo

**Axions, Neutralinos,** **Gravitinos, Axinos, Kaluza-Klein Photons, Kaluza-Klein Neutrinos, Heavy Fourth Generation Neutrinos, Mirror Photons, Mirror Nuclei, Stable States in Little Higgs Theories, WIMPzillas, Cryptons, Sterile Neutrinos, Sneutrinos, Light Scalars, Q-Balls, D-Matter, Brane World Dark Matter, Primordial Black Holes, ...**

## Weakly Interacting Massive Particles (WIMPs)

- As a result of the thermal freeze-out process, a relic density of WIMPs is left behind:
-            h2 ~ xF / <v>
- For a particle with a GeV-TeV mass, to obtain a thermal abundance equal to the observed dark matter density, we need an annihilation cross section of <v> ~ pb
- Generic weak interaction yields:
- <v> ~ 2 (100 GeV)-2 ~ pb

## Weakly Interacting Massive Particles (WIMPs)

- As a result of the thermal freeze-out process, a relic density of WIMPs is left behind:
-            h2 ~ xF / <v>
- For a particle with a GeV-TeV mass, to obtain a thermal abundance equal to the observed dark matter density, we need an annihilation cross section of <v> ~ pb
- Generic weak interaction yields:
- <v> ~ 2 (100 GeV)-2 ~ pb

- Numerical coincidence?  Or an indication that dark matter originates from EW physics?

## Supersymmetry

**Supersymmetry**

- Perhaps the most theoretically appealing (certainly the most well studied) extension of the Standard Model
- Natural solution to hierarchy problem (stabilizes quadradic divergences to Higgs mass)
- Restores unification of couplings
- Vital ingredient of string theory
- Naturally provides a compelling candidate for dark matter

## Supersymmetric Dark Matter

- R-parity must be introduced in supersymmetry to prevent rapid proton decay
- Another consequence of R-parity is that superpartners can only be created and destroyed in pairs, making the lightest supersymmetric particle (LSP) stable
- Possible WIMP candidates from supersymmetry include:

-  , Z, h, H

-  ~  ~  ~

- ~

- 

- 4 Neutralinos

- 

- ~

- 3 Sneutrinos

## Supersymmetric Dark Matter

- R-parity must be introduced in supersymmetry to prevent rapid proton decay
- Another consequence of R-parity is that superpartners can only be created and destroyed in pairs, making the lightest supersymmetric particle (LSP) stable
- Possible WIMP candidates from supersymmetry include:

-  , Z, h, H

-  ~  ~  ~

- ~

- 

- 4 Neutralinos

- 

- ~

- 3 Sneutrinos

- Excluded by direct detection

## Supersymmetry at the Tevatron

- Most promising channel is through neutralino-chargino production
- For example:
- Currently sensitive to charginos as heavy as ~140 GeV
- Tevatron searches for light squarks and gluinos are also very interesting
- For the case of light mA and large  tan, heavy MSSM higgs bosons (A/H) may be observable

## Supersymmetry at the LHC

- Squarks and gluinos produced prolifically at the LHC
- Subsequent decays result in distinctive combinations of leptons, jets and missing energy

**T. Plehn, Prospino 2.0**

- Squarks and gluinos up to 1 TeV can be discovered with 1% of the first year design luminosity
- Ultimately, LHC can probe squarks and gluinos up to ~3 TeV

## Supersymmetry at the LHC

- Kinematics of squark/gluino decays can reveal masses of squarks, gluinos, sleptons and neutralinos involved
- If many superpartners are light (bulk region), much of the sparticle spectrum could be reconstructed at the LHC

- What Can We Learn About Supersymmetry At The LHC?

**E. Baltz, et al, hep-ph/0602187**

## Supersymmetry at the LHC

- Kinematics of squark/gluino decays can reveal masses of squarks, gluinos, sleptons and neutralinos involved
- If many superpartners are light (bulk region), most/much of the sparticle spectrum could be reconstructed at the LHC

- What Can We Learn About Supersymmetry At The LHC?

**E. Baltz, et al, hep-ph/0602187**

**But we might not be so lucky!**

## Supersymmetry at the LHC

- For moderate and heavy SUSY models, the LHC will reveal far fewer superpartners
- It is not at all unlikely that the LHC could uncover a spectrum of squarks, gluinos and one neutralino
- Other than one mass, this would tell us next to nothing about the neutralino sector

- What Can We Learn About Supersymmetry At The LHC?

**E. Baltz, et al, hep-ph/0602187**

## Studying Supersymmetry With Neutralino Dark Matter

- Unless several of the neutralinos are light enough to be discovered at the LHC, we will learn very little about the composition and couplings of the lightest neutralino
- Astrophysical dark matter experiments provide another way to probe these couplings
- Potentially enable us to constrain/measure parameters appearing in the neutralino mass matrix: , M1, M2, tan

## Astrophysical Probes of Particle Dark Matter

**Direct Detection** 			-Momentum transfer to detector   	    through elastic scattering
**Indirect Detection** 			-Observation of annihilation 	    products (, , e+, p, etc.)

## Direct Detection

**Direct Detection**

- Neutralino-nuclei elastic scattering can occur through Higgs and squark exchange diagrams:

- Cross section depends on numerous SUSY parameters: neutralino mass and composition, tan, squark masses and mixings, Higgs masses and mixings

**SUSY Models**

## Slide 19

## Direct Detection

**Direct Detection**

- Current Status:

**CDMS**

**Zeplin, Edelweiss**

**DAMA**

**Supersymmetric **
**Models**

## Direct Detection

**Direct Detection**

- Near-Future Prospects:

**CDMS**

**Zeplin, Edelweiss**

**DAMA**

**Supersymmetric **
**Models**

**CDMS 2007 Projection**

## Direct Detection

**Direct Detection**

- Long-Term Prospects:

**CDMS**

**Zeplin, Edelweiss**

**DAMA**

**Supersymmetric **
**Models**

**Super-CDMS, Zeplin-Max **

## Direct Detection

- But what does direct detection tell us?

**Hooper and A. Taylor, hep-ph/0607086**

- Neutralino *is* dark matter                (sec vs. cosmological time scales)
- Models with large cross       sections are dominated by        Higgs exchange, couplings              to b, s quarks
- Squark exchange contribution substantial only below ~10-8 pb
- Leads to correlation between neutralino composition, tan, mA  and the elastic scattering rate

## Direct Detection And The Tevatron

- Correlation between neutralino composition, tan, mA and the elastic scattering rate (large tan, small mA leads to a large elastic scattering rate)
- MSSM Higgs searches at the Tevatron are also most sensitive to large tan, small mA ** **

**M. Carena, Hooper and P. Skands, PRL, hep-ph/0603180**** **

## Direct Detection And The Tevatron

**M. Carena, Hooper and P. Skands, PRL, hep-ph/0603180**** **

- Current CDMS Limit

- For a wide range of M2 and ,  much stronger current limits on tan, mA from CDMS than from the Tevatron

## Direct Detection And The Tevatron

**M. Carena, Hooper and P. Skands, PRL, hep-ph/0603180**** **

- Limits from CDMS imply heavy, neutral MSSM Higgs (H/A) are beyond the reach of the Tevatron, unless the LSP has a very small higgsino fraction (>>M2)** **

- 3 discovery reach, 4 fb-1

- Projected 2007 CDMS Limit (assuming no detection)

## Direct Detection And The Tevatron

**M. Carena, Hooper and P. Skands, PRL, hep-ph/0603180**** **

- H/A discovery (3, 4 fb-1) not expected given current CDMS limit

- H/A discovery (3, 4 fb-1) not expected given projected 2007 CDMS limits (assuming no detection)

## Indirect Detection With Neutrinos

- Neutralinos elastically scatter with nuclei in the Sun, becoming gravitationally bound
- As neutralinos accumulate in the Sun’s core, they annihilate at an increasing rate
- After ~Gyr, annihilation rate typically reaches equilibrium with capture rate, generating a potentially observable flux of high-energy neutrinos

## Indirect Detection With Neutrinos

- Muon neutrinos from the Sun interacting via charged current produce energetic muons
- Kilometer-scale neutrino telescope IceCube currently under construction at South Pole

## Indirect Detection With Neutrinos

- Rate observed at IceCube depends primarily on the neutralino capture rate in the Sun (the elastic scattering cross section)
- The reach of neutrino telescopes is, therefore, expected to be tied to that of direct detection experiments

## Indirect Detection With Neutrinos

- Important Caveat: WIMPs scatter with nuclei in the Sun through *both* spin-independent and spin-dependent scattering
- Sensitivity of direct detection to spin-dependent scattering is currently very weak

_**Spin-Independent**_

_**Spin-Dependent**_

**F. Halzen and Hooper, PRD, hep-ph/0510048**** **

## Indirect Detection With Neutrinos

- What kind of neutralino has large spin-dependent couplings?

- 

- q

- q

- Z

- q

- q

**Always Small**

******  ****[ |f****H1****|****2**** - |f****H2****|****2 ****]****2**

**Substantial Higgsino Component Needed**

## Indirect Detection With Neutrinos

- What kind of neutralino has large spin-dependent couplings?

- High Neutrino Rates

**Hooper and A. Taylor, hep-ph/0607086;                               F. Halzen and Hooper, PRD, hep-ph/0510048**** **

## Indirect Detection With Neutrinos

- Rates complicated by competing scalar and axial-vector scattering processes

**Hooper and A. Taylor, hep-ph/0607086;                               F. Halzen and Hooper, PRD, hep-ph/0510048**** **

**Current CDMS Constraint**

## Indirect Detection With Neutrinos

- Rates complicated by competing scalar and axial-vector scattering processes; but becomes simple with future bounds

**Hooper and A. Taylor, hep-ph/0607086;                               F. Halzen and Hooper, PRD, hep-ph/0510048**** **

**Current CDMS Constraint**

- High Neutrino Rates

**100 Times Stronger Constraint**

## Indirect Detection With Gamma-Rays

- _Advantages of Gamma-Rays_:
- Propagate undeflected (point sources possible)
- Propagate without energy loss (spectral information)
- Distinctive spectral features (lines), provide potential “smoking gun”
- Wide range of experimental technology (ACTs, satellite-based)

## Indirect Detection With Gamma-Rays

- What does the gamma-ray spectrum tell us?
- Most annihilation modes generate very similar spectra
- +- mode is the most distinctive, although still not identifiable with planned experiments (GLAST, etc.)
- Neutralino mass and annihilation rate may be roughly extracted

**Hooper and A. Taylor, hep-ph/0607086**

## Indirect Detection With Gamma-Rays

- What does the gamma-ray spectrum tell us?
- At loop level, neutralinos annihilate to  and Z final states
- Distinctive spectral line features
- If bright enough, fraction of neutralino annihilations to lines can be measured

## Indirect Detection With Gamma-Rays

- What does the gamma-ray spectrum tell us?
- Chargino-W+/- loop diagrams provide largest contributions in most models
- Cross sections largest for higgsino-like (or wino-like) neutralinos
- Knowledge of squark masses makes this correlation more powerful

**Hooper and A. Taylor, hep-ph/0607086**

## Information From Anti-Matter

- Gamma-ray observations can tell us the fraction of neutralino annihilation to various modes (, Z), but cannot measure the total cross section
- Positron spectrum generated in neutralino annihilations is dominated by local dark matter distribution (within a few kpc)
- Considerably less uncertainty in the local density than the density of inner halo
- Cosmic positron measurements can       roughly measure the neutralino’s     total annihilation cross section

## Putting It All Together

**                   **

**Direct Detection**

**Neutrino Telescopes**

******-Rays + e****+**

## Putting It All Together

## Studying SUSY with the LHC and Astrophysics

**                   **

- _Benchmark model IM3:_
- SUSY Inputs:**  **M2=673 GeV, =619 GeV, mA=397 GeV, tan=51, 				2130 GeV squarks
- Measured by the LHC:** **m= 236 ± 10%, msquark=2130 ± 30%,              		tan=51 ± 15%, mA=397 ± 1%**  ****	****	****	****	****	**** **(no sleptons, charginos, or heavy neutralinos)
- Measured by astrophysical experiments: N=9.6 10-9 pb x/ 2, 		R < 10 yr-1, +Z / tot < 10-5

## Studying SUSY with the LHC and Astrophysics

**                   **

- _Benchmark model IM3:_

- LHC+Relic Density

- Actual Value

- +Astro

**Hooper and A. Taylor, hep-ph/0607086**

## Studying SUSY with the LHC and Astrophysics

**                   **

- _Benchmark model IM1:_
- SUSY Inputs:**  **M2=551 GeV, =1318 GeV, mA=580 GeV, 				tan=6.8, 2240 GeV squarks
- Measured by the LHC:** **m= 276 ± 10%, msquark=2240 ± 30%,              		** **(no sleptons, charginos, heavy neutralinos, 				heavy Higgs bosons or tan)
- Measured by astrophysical experiments: N < 10-10 pb, 		R < 10 yr-1, +Z / tot < 10-4 to 10-6

## Studying SUSY with the LHC and Astrophysics

**                   **

- _Benchmark model IM1:_

**Hooper and A. Taylor, hep-ph/0607086**

- LHC+Relic Density

- Actual Value

## Studying SUSY with the LHC and Astrophysics

**                   **

- _Benchmark model IM1:_

**Hooper and A. Taylor, hep-ph/0607086**

- Actual Value

- +Astro

- LHC+Relic Density

## Studying SUSY with the LHC and Astrophysics

**                   **

- _Benchmark model IM1:_

**Hooper and A. Taylor, hep-ph/0607086**

- LHC+Relic Density

- Actual Value

- +Astro

## Is It SUSY?

- Thus far, we have assumed that the new particles seen at the Tevatron/LHC and in dark matter experiments are superpartners of SM particles
- Several alternatives to supersymmetry have been proposed which may effectively mimic the signatures of supersymmetry at the LHC

## Is It SUSY?

- _Universal Extra Dimensions (UED)_
- All SM particles allowed to travel around extra dimension(s) with size ~TeV-1
- Particles moving around extra dimensions appear as heavy versions of SM particles (Kaluza-Klein modes)
- The lightest Kaluza-Klein particle can be stable, weakly interacting and a suitable candidate for dark matter
- Can we distinguish Kaluza-Klein modes from superpartners?

## Is It SUSY?

**Is It SUSY?**

- _Discriminating Supersymmetry and UED at the LHC_
- Squarks and gluinos or KK quarks 				and KK gluons cascade to combinations 			   of jets, leptons and missing energy; mass 			measurements possible, but are they 				sparticles or KK states? 						        	 Spin-determination crucial

## Is It SUSY?

**Is It SUSY?**

- _Discriminating Supersymmetry and UED at the LHC_
- Recent literature on SUSY/UED discrimination: 				(see Cheng, Matchev, Schmaltz; Datta, Kong, 				Matchev; Datta, Kane, Toharia; Alves, Eboli, 				Plehn; Athanasiou, Lester, Smilie, Webber)
- In the case of somewhat heavy masses or 			quasi-degenerate spectra, spin determination 			becomes very challenging/impossible
- The observation of 2nd level 					  KK modes would bolster case 					   for UED, but could be confused 					with a Z prime, for example

## Is It SUSY?

**Is It SUSY?**

- _Discriminating Supersymmetry and UED with Dark Matter_
- Kalzua-Klein dark matter (KK ‘photon’, B(1)) annihilates primarily to charged leptons pairs (20-25% to each of e+e-, +- and +-)
- Neutarlino annihilations to light fermions, 			    in contrast, are chirality suppressed 			                  	(v  [mf/m]2)
- This difference can lead to 					very distinctive signatures in 					indirect dark matter experiments

## Is It SUSY?

- The Gamma-Ray Annihilation Spectrum
-            Neutralino annihilations to gauge/Higgs bosons and 		heavy quarks produce rather soft gamma-ray spectrum

## Is It SUSY?

- The Gamma-Ray Annihilation Spectrum
-            Kaluza-Klein dark matter particles produce harder 		spectrum due to 20-25% annihilation to tau pairs, and		 final state radiation

- Total, including ’s and FSR

- Quark fragmentation alone (SUSY-like)

- Including ’s

## Is It SUSY?

**Is It SUSY?**

- The Cosmic Positron Spectrum
-            Annihilations to e+e- ( and +-, +-) generate                                              	distinctive hard spectrum with edge

- UED Case

- Gauge Bosons, Heavy Quarks

- background

- (mDM=300 GeV, BF=5, moderate propagation)

## Is It SUSY?

**Is It SUSY?**

- The Cosmic Positron Spectrum
-            Clearly identifiable by future experiments 	(Pamela, AMS-02) for light/moderate masses

- UED Case

- Gauge Bosons, Heavy Quarks

- background

- (mDM=300 GeV, BF=5, moderate propagation)

- Pamela

## Supersymmetry in the ILC Era

- Combined with LHC data, likely able to measure much/most/all of the sparticle and Higgs masses
- With such knowledge of the particle spectrum, it may become possible to accurately calculate the expected relic abundance of neutralinos, and compare this to the observed dark matter density

## Supersymmetry in the ILC Era

- Combined with LHC data, likely able to measure much/most/all of the sparticle and Higgs masses
- With such knowledge of the particle spectrum, it may become possible to accurately calculate the expected relic abundance of neutralinos, and compare this to the observed dark matter density

-   Confirmation that neutralinos make up the dark matter of our universe!

**But what if they don’t match?**

## Supersymmetry in the ILC Era

- SuperWIMP Scenario: neutralinos freeze-out, and later decay to gravitinos
- Non-WIMP dark matter 					generated through WIMP-like 				freeze-out process
- No signal for direct or 					indirect detection

- _What if the calculated abundance doesn’t match astrophysical observations? _

- 

- g

- ~

## Supersymmetry in the ILC Era

- Relic abundance calculation assumes standard cosmological picture
- Non-standard cosmology/expansion history can lead to very different relic abundance		 			(see Lykken and Barenboim, last week)

- _What if the calculated abundance doesn’t match astrophysical observations? _

## Slide 62

## Current Observations

**Current Observations**

## The ILC Is A Window Into The Early Universe!

**Current Observations**

**Terascale Observations**

## Summary

- If (low-scale) supersymmetry exists in nature, then the LHC is exceedingly likely to discover superpartners
- The sparticle spectrum measured by the LHC will be very incomplete unless most of the sparticles are very light
- To learn more about the SUSY spectrum with colliders, we may have to wait for the ILC

## Summary

- If (low-scale) supersymmetry exists in nature, then the LHC is exceedingly likely to discover superpartners
- The sparticle spectrum measured by the LHC will be very incomplete unless most of the sparticles are very light
- To learn more about the SUSY spectrum with colliders, we may have to wait for the ILC

- (but I’m not that patient!)

## Summary

- Direct and indirect detection of dark matter can provide additional information on the couplings/composition of the lightest neutralino and masses of exchanged particles
- In many cases, dark matter measurements can break degeneracies between bulk/funnel/coannihilation regions of parameter space
- For models in the A-funnel 					region of parameter space, 					mA can often be determined 					by astrophysical measurements
- Astrophysical probes of neutralino 				dark matter can fill in some of the gaps 				in our post-LHC/pre-ILC understanding of supersymmetry

## Let’s use all of the tools we have to solve the puzzles of the terascale!

** ****I  C  E  C  U  B  E**

**GLAST**

**A**

**I   C  E**

**P**

**M  E  L  A**

**M S**

**D M S**

**ANTA**

**RES**

**A  T  L        S**

**ZEPLIN**

**DZERO**

**VERITAS**

**M A  G  I   C**

**CDF**

**CMS**

**H   E  S**

**Let’s use all of the tools we have to solve the puzzles of the terascale!**

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- In bookstores November 2006