GravitinoGravitino DarkDark mattermatter thethe darkestdarkest darkdark mattermatter • Coupling / 1/mpl • no signal for direct/indirect DM searches • can not be produced at colliders New proposal:not very excitingsuperWIMP DM • naturally obtain Ω • solve BBN 7Li anomaly • Could be tested at colliders Shufang Su • U. of Arizona Aspen Winter Conference 2005 OutlineOutline Gravitino Gravitino as warm Dark Matter Gravitino as cold Dark Matter superWIMP Constraints - Late time energy injection and BBN Collider phenomenology Slepton trapping Conclusion S. Su Gravitino Dark Matter 2 GravitinoGravitino • Gravitino: superpartner of graviton ~ • Obtain mass whenwhen 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 Gravitino Dark Matter 3 Gravitino:Gravitino: warmwarm darkdark mattermatter ~ mG ¿ mSUSY (GMSB) 2 ~ Ω h » (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 Gravitino Dark Matter 4 GravitinoGravitino coldcold darkdark mattermatter ~ mG » mSUSY » GeV – TeV (supergravity) ~ ~ G χ~, ~ ~ ~ LSP l LSP ~ χ, l G superWIMP thermal -1 Ωthermal ∝ 〈σ 〉-1 thermal -1 Ω LSP ∝ 〈σv〉 Ω ∝ 〈σv〉 DM WIMP LSP -2 ∝ (weak coupling) ∝ (gravitational coupling)-2 ~ G → LSP + SM ● 〈σv〉 too small BBN constraints: 5 8 th ~ TRH < 10 – 10 GeV ● Ω G too big Kawasaki, Kohri and Moroi, overclose the Universe asrtro-ph/0402490, astro-ph/0408426 10 unless TRH < 10 GeV Conflict with thermal leptogenesis: Bolz, Brandenburg and Buchmuller, 9 TRH > 3 £ 10 GeV NPB 606, 518 (2001) S. Su Buchmuller, Bari, Plumacher, NPB665,Gravitino 445 (2003) Dark Matter 5 WIMPWIMP →→ SWIMPSWIMP ++ SMSM particleparticle FRT hep-ph/0302215, 0306024 WIMP 104 s < t < 108 s SWIMPSM • Gravitino LSP • LKK graviton 106 S. Su Gravitino Dark Matter 6 SuperWIMPSuperWIMP andand SUSYSUSY WIMPWIMP ~ ~ • SUSY case SWIMP: G (LSP) 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 EM BBN had -3 Brhad > O(0.01) Brhad ≤ O(10 ) S. Su Gravitino Dark Matter 7 ConstraintsConstraints ~ → NLSP → G + SM particles η/10-10 = 6.1± 0.4 ~ c Dark matter density ΩG · 0.23 th ΩSWIMP=(mSWIMP/mNLSP) Ω NLSP d CMB photon energy distribution e Big bang nucleosynthesis Late time EM/had injection could change the BBN prediction of light elements abundances Fields, Sarkar, PDG (2002) S. Su Gravitino Dark Matter 8 BBNBBN constraintsconstraints onon EM/hadEM/had injectioninjection • Decay lifetime τNLSP around a year • EM/had energy release ξEM,had=εEM,had BrEM,had YNLSP » ~ » mNLSP-mG had EM (GeV) EM ξ EM Cyburt, Ellis, Fields and Olive, PRD 67, 103521 (2003) Kawasaki, Kohri and Moroi, astro-ph/0402490 S. Su Gravitino Dark Matter 9 sleptonslepton andand sneutrinosneutrino NNLSPLSP J. Feng, F. Takayama, S. Su ~ ~ th ΩG = (mG/mNLSP) Ω NLSP hep-ph/0404198, 0404231 τNLSP, ξEM,had=εEM,had BEM,had YNLSP apply CMB and BBN constraints on (τNLSP, ξEM/had ) ⇒ viable parameter space S. Su Gravitino Dark Matter 10 superWIMPsuperWIMP inin mSUGRAmSUGRA Ellis et. al., hep-ph/0312262 BBN EM constraints only Usual WIMP allowed region superWIMP allowed region Stau NLSP S. Su Gravitino Dark Matter 11 ColliderCollider PhenomenologyPhenomenology SWIMP Dark Matter × no signals in direct / indirect dark matter searches 9 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) • τ(GMSB) ¿ τ(SWIMP): distinguish experimentally Feng and Smith, in preparation. S. Su Gravitino Dark Matter 12 GuaranteedGuaranteed signalsignal atat colliderscolliders Feng, SS, Takayama, in preparation Model independent approach: ΩDM ⇒ <σ v>ann ⇒ σproduction Birkedal, matchev, Perelstein, PRD 70, 077701 (2004). • Usual WIMP: missing energy + jet or photon irreducible SM background • superWIMP: promising event rates at LHC/LC. preliminary preliminary S. Su Gravitino Dark Matter 13 SneutrinoSneutrino aandnd neutralinoneutralino NNLSPLSP • sneutrino and neutralino NLSP missing energy signal: energetic jets/leptons + missing energy c Is the lightest SM superpartner sneutrino or neutralino? − angular distribution of events (LC) vs. d 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 th precision determination of SUSY parameter: Ω χ∼,∼ν Ωχ∼,ν∼ > 0.23 ⇒ favor gravitino LSP S. Su Gravitino Dark Matter 14 ● Decay life time ● SM particle energy/angular distribution … ~ ⇒ mG ⇒ m NLSPSM pl ~ ⇒ LFV G NLSPSM SM NLSP ~ … ~ G G NLSPSM Buchmuller et. al., hep-ph/0402179 SM ~ NLSP G Hamaguchi and Ibarra, hep-ph/0412229 Feng et. al., Hep-ph/0405248 ~ G Slepton trapping: Hamaguchi et. al. hep-ph/0409248 Feng and Smith, hep-ph/0409278 S. Su Gravitino Dark Matter 15 SleptonSlepton ttrappingrapping 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. 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 S. Su Gravitino Dark Matter 16 Courtesy of J. Feng ConclusionsConclusions Gravitino could be warm DM: m » keV Gravitino could be cold DM: m » few hundred GeV 10 − thermal production: TRH< 10 GeV − Non-thermal production: superWIMP WIMP → superWIMP + SM particle SuperWIMP: gravitino LSP WIMP: slepton/sneutrino/neutralino Constraints from BBN: EM injection and hadronic injection viable parameter space Rich collider phenomenology (no direct/indirect DM signal) − charged slepton: highly ionizing track − sneutrino/neutralino: missing energy Slepton trapping S. Su Gravitino Dark Matter 17.