1. Shufang Su • U. of Arizona
SuperWIMP Dark matter
in SUSY with a Gravitino LSP
Shufang Su • U. of Arizona
See also, Jonathan Feng’s talk,
SuperWIMPs and Slepton Traps
J. Feng, F. Takayama, S. Su
hep-ph/ ,

2. Why is the gravitino not usually considered as DM?-
In supergravity, for mG » GeV – TeV ~
thG  v-1  (gravitional coupling)-2
(comparig to WIMP of weak coupling strength)
v too small
thG too big, overclose the Universe ~
However, gravitino can get relic density by other means
SuperWIMP
S. Su SWIMP

3. WIMP  SWIMP + SM particle-
FRT hep-ph/ ,
WIMP
104 s  t  108 s
SWIMP SM
 Gravitino LSP
 LKK graviton
106
S. Su SWIMP

4. Outline SWIMP dark matter and gravitino LSP Constraints-
SWIMP dark matter and gravitino LSP
Constraints
Late time energy injection and BBN
NLSP  gravitino +SM particle
slepton, sneutrino, neutralino
- approach I: fix SWIMP=0.23
- approach II: SWIMP=(mSWIMP/mNLSP) thNLSP
Collider phenomenology
Conclusion
Updates since Jan SLAC LC workshop
S. Su SWIMP

5. SWIMP and SUSY WIMP SWIMP: G (LSP) WIMP: NLSP mG » mNLSP ~ SUSY case-
SWIMP: G (LSP) WIMP: NLSP mG » mNLSP ~
SUSY case ~
Ellis et. al., hep-ph/ ; Wang and Yang, hep-ph/
104 s  t  108 s
NLSP  G + SM particles ~
neutralino/chargino NLSP
slepton/sneutrino NLSP
BBN EM
had
Brhad  O(0.01)
Brhad  O(10-3)
S. Su SWIMP

6. Constraints ~ NLSP  G + SM particles  Dark matter density G · 0.23- ~
NLSP  G + SM particles
/10-10 = 6.1 0.4
Fields, Sarkar, PDG (2002)
 Dark matter density G · 0.23 ~
- approach I: fix SWIMP=0.23
- approach II: SWIMP=(mSWIMP/mNLSP) thNLSP
 CMB photon energy distribution
 Big bang nucleosynthesis
Late time EM/had injection could
change the BBN prediction of
light elements abundances
S. Su SWIMP

7. BBN constraints on EM/had injection-
Decay lifetime NLSP
EM/had energy release
EM,had=EM,had BrEM,had YNLSP
Cyburt, Ellis, Fields and Olive, PRD 67, (2003) EM
EM (GeV)
» mNLSP-mG ~
Kawasaki, Kohri and Moroi, astro-ph/
had EM
S. Su SWIMP

8. YNLSP: approach I approach I: fix G = 0.23 ~ slepton and sneutrino-
approach I: fix G = 0.23 ~
slepton and sneutrino
200 GeV ·  m · 400 » 1500 GeV
mG ¸ 200 GeV ~
 m · 80 » 300 GeV
apply CMB and BBN constraints on (NLSP, EM/had )
 viable parameter space
NLSP, EM,had=EM,had BEM,had YNLSP
S. Su SWIMP

9. Approach II: slepton and sneutrino-
G = (mG/mNLSP) thNLSP ~
S. Su SWIMP

10. Distinguish from stau NLSP and gravitino LSP in GMSB
Collider Phenomenology -
SWIMP Dark Matter
no signals in direct / indirect dark matter searches
SUSY NLSP: rich collider phenomenology
NLSP in SWIMP: long lifetime  stable inside the detector
Charged slepton highly ionizing track, almost background free
Distinguish from stau NLSP and gravitino LSP in GMSB
GMSB: gravitino m » keV warm not cold DM
collider searches: other sparticle (mass)
(GMSB) ¿ (SWIMP): distinguish experimentally
Feng and Smith, in preparation.
S. Su SWIMP

11. Sneutrino and neutralino NLSP-
sneutrino and neutralino NLSP missing energy
signal: energetic jets/leptons + missing energy
 Is the lightest SM superpartner sneutrino or neutralino?
angular distribution of events (LC)
vs.
 Does it decay into gravitino or not?
sneutrino case: most likely gravitino is LSP
neutralino case: most likely neutralino LSP
direct/indirect dark matter search
positive detection  disfavor gravitino LSP
precision determination of SUSY parameter: th, ~ ~
,  0.23  favor gravitino LSP ~
S. Su SWIMP

12. SM energy distribution  Mpl
Decay life time
SM energy distribution
 Mpl
 mG
 SUSY breaking scale ~ SM
NLSP ~ G
NLSP SM SM
NLSP ~ G
Capture particle:
Goity, Kossler and Sher,
hep-ph/ ~ G SM
NLSP
NLSP SM ~ G
Supergravity at colliders
Buchmuller et. al.
hep-ph/ ~ G
SWIMPs and slepton traps
Feng and Smith
In preparation…
See Feng’s talk
S. Su SWIMP

13. Conclusions SuperWIMP is possible candidate for dark matter-
SuperWIMP is possible candidate for dark matter
SUSY models
SWIMP: gravitino LSP WIMP: slepton/sneutrino/neutralino
Constraints from BBN: EM injection and hadronic injection
need updated studies of BBN constraints on hadronic/EM injection
Favored mass region
Approach I: fix G=0.23
Approach II: G = (mG/mNLSP) thNLSP
Rich collider phenomenology (no direct/indirect DM signal)
charged slepton: highly ionizing track
sneutrino/neutralino: missing energy
Other implications … ~ ~ ~
S. Su SWIMP