Transcript ASBS2 - University of Arizona

superWIMP Dark matter
the darkest dark matter
 Coupling / 1/mpl (very suppressed)
 no signal for direct/indirect DM searches
 can not be produced at colliders
not Su
very •exciting
Shufang
U. of Arizona
 naturally obtain 
 solve BBN 7Li anomaly
 could be tested at colliders
Work collaborated with
J. Feng, F. Takayama
Outline
WIMP and superWIMP dark matter
Gravitino LSP as superWIMP
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
Slepton trapping
Conclusion
S. Su SWIMP
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Dark Matter (DM)




Non-baryonic
Stable
Neutral
Cold
DM h2=0.112 § 0.009
 Can not be any of the known particles
 microscopic identity of DM ?
WIMP
and
superWIMP
 appear in particle physics models motivated independently
by attempts to solve EWSB
 relic density are determined by Mpl and Mweak
 naturally around the observed value
 no need to introduce and adjust new energy scale
S. Su SWIMP
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WIMP
Thermalequation
equilibrium
Boltzmann
 $ ff
WIMP
expansion
Universe
cools:
n=nEQe-m/T
WIMP » h anFreeze
v i-1
  ff
out, n/s » const
 mWIMP» Mweak
 an » weak2 Mweak-2
naturally around
the observed value
e.g. neutralino LSP
ff  
=n hvi
v.s. H
− early time   H
n ¼ neq
− late time   H
(n/s)today » (n/s)decoupling
− at freeze-out ¼ H
TF » m/25
Approximately, relic / 1/hvi
S. Su SWIMP
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superWIMP
WIMP  superWIMP + SM particles
FRT hep-ph/0302215, 0306024
104 s  t  108 s
SWIMP
SM
WIMP
superWIMP
e.g. Gravitino LSP
LKK graviton
WIMP
106
S. Su SWIMP
 neutral
 charged
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Gravitino
 Gravitino: superpartner of graviton
 Obtain mass when SUSY is spontaneously broken mG~ » F/mpl
 Stable when it is LSP - candidate of Dark Matter
mG~ ¿ mSUSY
mG~ » mSUSY
» keV
» GeV – TeV
warm Dark Matter
cold Dark Matter
S. Su SWIMP
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Gravitino: warm dark matter
mG~ ¿ mSUSY
(GMSB)
 h2 » (mG~/keV) (100/g*)
 mG~ » keV : warm Dark Matter
 mG~  keV : problematic !
gravitino dilution necessary
 stringent bounds on reheating temp.
Moroi, Murayama and Yamaguchi, PLB303, 289 (1993)
S. Su SWIMP
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Gravitino cold dark matter
mG~ » mSUSY » GeV – TeV
~
G
LSP
~
, ~
l
thermalLSP  v-1
 (weak
coupling)-2
WIMP
~
G  LSP + SM
BBN constraints:
TRH  105 – 108 GeV
Kawasaki, Kohri and Moroi,
asrtro-ph/0402490, astro-ph/0408426
Conflict with thermal leptogenesis:
TRH  3 £ 109 GeV
Buchmuller, Bari, Plumacher,
NPB665, 445 (2003)
(supergravity)
~
, ~
l
thermalLSP  v-1
~
G
LSP
superWIMP
DM
 (gravitational coupling)-2
● v too small
● thG~ too big
overclose the Universe
unless TRH  1010 GeV
Bolz, Brandenburg and Buchmuller,NPB 606, 518 (2001)
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superWIMP : an example
SUSY case
WIMP  superWIMP + SM particles
NLSP: slepton/sneutrino
neutralino/chargino
Gravitino LSP
Superpartner of graviton
superWIMP
1
»
mpl2
WIMP
SM particle
Decay lifetime  planck mass
S. Su SWIMP
change light element
abundance predicted
by BBN
Strong constraints !
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superWIMP and SUSY WIMP
neutralino/chargino NLSP
slepton/sneutrino NLSP
Brhad  O(0.01)
Brhad  O(10-3)
EM
BBN
had
S. Su SWIMP
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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
S. Su SWIMP
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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
S. Su SWIMP
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)
S. Su SWIMP
Kawasaki, Kohri and Moroi, astro-ph/0402490
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Decay lifetime
 Decay lifetime (sec)
~
~
B  G + /Z/h
S. Su SWIMP
~
~
~
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
S. Su SWIMP
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YNLSP: approach II
 approach II: G~ = (mG~/mNLSP) thNLSP
Approximately
 right-handed slepton
 sneutrino (left-handed slepton)
 neutralino
- “bulk”
S. Su SWIMP
-“focus point/co-annihilation”
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Approach II: slepton and sneutrino
G~ = (m~G/mNLSP) thNLSP
S. Su SWIMP
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Approach II: bino
G~ = (m~G/mNLSP) thNLSP
S. Su SWIMP
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superWIMP in mSUGRA
Ellis et. al., hep-ph/0312262
BBN EM constraints only
Usual WIMP allowed region
superWIMP allowed region
Stau NLSP
S. Su SWIMP
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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
S. Su SWIMP
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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
S. Su SWIMP
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● Decay life time
● SM particle energy/angular
distribution …
 mG~
 mpl …
 Probes gravity in a particle
physics experiments!
SM
NLSP
SM
NLSP
~
G
SM
NLSP
 BBN, CMB in the lab
~
G
~
G
SM
NLSP
~
G
SM
NLSP
 Precise test of supergravity:
gravitino is a graviton partner
~
G
How to trap slepton?
Hamaguchi, kuno, Nakaya, Nojiri, hep-ph/0409248
Feng and Smith, hep-ph/0409278
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Slepton trapping
Feng and Smith, hep-ph/0409278
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 are fast.
Catch 100/yr in 1 kton water
 LC: tune beam energy to produce
slow sleptons,
can catch 1000/yr in 1 kton water
S. Su SWIMP
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Conclusions
SuperWIMP is possible candidate for dark matter
WIMP  superWIMP + SM particle
SUSY models
SWIMP: gravitino LSP WIMP: slepton/sneutrino/neutralino
Constraints from BBN: EM injection and hadronic 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
slepton trapping
S. Su SWIMP
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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
S. Su SWIMP
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