1. Shufang Su • U. of Arizona
SuperWIMP Dark matter
in SUSY with a Gravitino LSP
Shufang Su • U. of Arizona
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. 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
S. Su SWIMP

4. WIMP  SWIMP + SM particle-
FRT hep-ph/ ,
WIMP
104 s  t  108 s
SWIMP SM
 Gravitino LSP
 LKK graviton
106
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
 Dark matter density G · 0.23 ~
Approach I
Approach II
SWIMP close universe
SWIMP maybe insiginificant
nNLSP  SWIMP/mSWIMP1/mSWIMP
 1/mSUSY
thNLSP  v-1  m2SUSY
 nNLSP  mSUSY
NLSP: slepton,sneutrino
neutralino : excluded
NLSP: slepton, sneutrino,
neutralino
fix G = 0.23 ~
G = mG/mNLSP thNLSP ~
S. Su SWIMP

7. Constraints (cont’)  CMB photon energy distribution-
 CMB photon energy distribution
- early decay:  = 0
thermalized through e  e, eX  eX , e  e
- late decay:   0
statistical but not thermodynamical equilibrium
|| · 9 £ 10-5
Fixsen et. al., astro-ph/
Hagiwara et. al., PDG
S. Su SWIMP

8. Constraints (cont’) ?  Big bang nucleosynthesis /10-10 = 6.1 0.4
Fields, Sarkar, PDG (2002)
S. Su SWIMP

9. 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

10. Decay lifetime Decay lifetime (sec) ~ ~ l  G + l,  ! G + -
Decay lifetime (sec)
l  G + l,  ! G +  ~
B  G + /Z/h ~
S. Su SWIMP

11. EM.had and BrEM, had EM, had » mNLSP-mG
EM/had branching ratio BrEM, had ~
neutralino
slepton
Sneutrino EM
mode
BrEM 1
had
Brhad
O(1)
O( )
S. Su SWIMP

12. 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

13. YNLSP: approach II approach II: G = (mG/mNLSP) thNLSP ~-
approach II: G = (mG/mNLSP) thNLSP ~
Approximately
right-handed slepton
sneutrino (left-handed slepton)
neutralino
“bulk” “focus point/co-annihilation”
S. Su SWIMP

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

15. Approach II: bino -
G = (mG/mNLSP) thNLSP ~
S. Su SWIMP

16. 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

17. 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

18. 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
distinguish from GMSB
sneutrino/neutralino: missing energy
stable or not? ~ ~ ~
S. Su SWIMP

19. 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…
S. Su SWIMP

20. Slepton trapping (from J. Feng)-
Slepton could live for a year, so can be trapped then moved
to a quiet environment to observe decays
LHC: 106 slepton/yr possible, but most a fast. By optimizing trap location and shape, can catch » 100/yr in 1000m3 water
LC: tune beam energy to produce slow sleptons, can catch 1000/yr in 1000m3 water
Courtesy of J. Feng
S. Su SWIMP

21. Frequently asked question

22. Something about  lepton-
  G +, ~
  mesons, induce hadronic cascade
meson decay before interact with BG hadrons
longer than typical meson (, K) lifetime (E/m)£ 10-8 s
S. Su SWIMP