Transcript ASBS2 - University of Arizona

SuperWIMP Dark matter
in SUSY with a Gravitino LSP
Shufang Su • U. of Arizona
J. Feng, F. Takayama, S. Su
hep-ph/0404198, 0404231
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
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Outline
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
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WIMP  SWIMP + SM particle
FRT hep-ph/0302215, 0306024
WIMP
104 s  t  108 s
SWIMP
SM
 Gravitino LSP
 LKK graviton
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SWIMP and SUSY WIMP
 SUSY case
~ (LSP)
SWIMP: G
WIMP: NLSP mG~ » mNLSP
Ellis et. al., hep-ph/0312262; Wang and Yang, hep-ph/0405186.
104 s  t  108 s
~
NLSP  G + SM particles
neutralino/chargino NLSP
slepton/sneutrino NLSP
Brhad  O(0.01)
Brhad  O(10-3)
EM
BBN
had
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Constraints
~
NLSP  G + SM particles
 Dark matter density G~ · 0.23
Approach I
fix ~G = 0.23
Approach II
G~ = m~G/mNLSP 
th
NLSP
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
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Constraints (cont’)
 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
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Fixsen et. al., astro-ph/9605054
Hagiwara et. al., PDG
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Constraints (cont’)
 Big bang nucleosynthesis
/10-10 = 6.1 0.4
?
Fields, Sarkar, PDG (2002)
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BBN constraints on EM/had injection
 Decay lifetime NLSP
 EM/had energy release
had
EM
EM (GeV)
» mNLSP-mG~
EM,had=EM,had BrEM,had
YNLSP
EM
Cyburt, Ellis, Fields and Olive, PRD 67, 103521 (2003) Kawasaki, Kohri and Moroi, astro-ph/0402490
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Decay lifetime
 Decay lifetime (sec)
~
~
B  G + /Z/h
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~
~
l  G + l, ~ ! G + 
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EM.had and BrEM, had
 EM, had » mNLSP-mG~
 EM/had branching ratio BrEM, had
neutralino
slepton
Sneutrino
1
1
0
O(1)
O(10-2 - 10-6)
mode
EM
BrEM
mode
had
Brhad
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YNLSP: approach I
 approach I: fix G~ = 0.23
200 GeV ·  m · 400 » 1500 GeV
, EM,had=EM,had BEM,had
mG~ 
¸ NLSP
200 GeV
slepton and sneutrino
YNLSP m
· 80 » 300 GeV
apply CMB and BBN constraints on (NLSP, EM/had )
 viable parameter space
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YNLSP: approach II
 approach II: G~ = (mG~/mNLSP) thNLSP
Approximately
 right-handed slepton
 sneutrino (left-handed slepton)
 neutralino
- “bulk”
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-“focus point/co-annihilation”
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Approach II: slepton and sneutrino
G~ = (m~G/mNLSP) thNLSP
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Approach II: bino
G~ = (m~G/mNLSP) thNLSP
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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.
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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
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Conclusions
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?
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● Decay life time
● SM energy distribution
 Mpl
 m~G
SM
NLSP
~
G
SM
NLSP
 SUSY breaking scale
SM
NLSP
~
G
~
G
SM
NLSP
SM
NLSP
~
G
~
G
Capture particle:
Goity, Kossler and Sher,
hep-ph/9305244
Supergravity at colliders
Buchmuller et. al.
hep-ph/0402179
SWIMPs and slepton traps
Feng and Smith
In preparation…
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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
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Frequently asked question
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
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