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Exploring WIMPs in Particle Physics: Dark Matter Interplay in Cosmology

This presentation delves into the realm of dark matter, focusing on WIMPs (weakly interacting massive particles) and their relic density in the Universe. It covers the SUSY case as an illustrative example, discussing the implications of CP violation and the requirements for collider tests. The interplay between cosmology and particle physics, particularly the discovery potential at the LHC and precision measurements at the ILC, is also explored. The neutralino dark matter candidate in the MSSM is discussed, along with collider tests of WIMPs and the relic density mechanisms to align with cosmological data. The importance of measuring parameters with precision for neutralinos and staus is emphasized for future experiments like the ILC.

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Exploring WIMPs in Particle Physics: Dark Matter Interplay in Cosmology

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  1. LHC / ILC / Cosmology InterplaySabine Kraml (CERN) WHEPP-9, Bhubaneswar, India 3-14 Jan 2006

  2. Outline • Introduction • Relic density of WIMPs • SUSY case as illustrative example • Neutralino dark matter • Requirements for collider tests • Implications of CP violation • Conclusions WHEPP-9 Bhubaneswar

  3. What is the Universe made of? • Cosmological data: • 4% ±0.4% baryonic matter • 23% ±4% dark matter • 73% ±4% dark energy • Particle physics: • SM is incomplete; expect new physics at TeV scale • NP should provide the DM • Discovery at LHC, precision measurements at ILC ? WHEPP-9 Bhubaneswar

  4. Dark matter candidates Neutralino, gravitino, axion, axino, lightest KK particle, T-odd little Higgs, branons, Q-balls, etc., etc... New Physics WHEPP-9 Bhubaneswar

  5. WIMPs (weakly interacting massive particles) • DM must be stable, electrically neutral, weakly and gravitationally interacting • WIMPs are predicted by most BSM theories • Stable as result of discrete symmetries • Produced as thermal relic of the Big Bang • Testable at colliders! Neutralino, gravitino, axion, axino, LKP, T-odd Little Higgs, branons, Q-balls, etc., ... WHEPP-9 Bhubaneswar

  6. Relic density of WIMPs • Early Universe dense and hot; WIMPs in thermal equilibrium • Universe expands and cools;WIMP density is reduced through pair annihilation; Boltzmann suppression: n~e-m/T • Temperature and densitytoo low for WIMP annihilation to keep up with expansion rate → freeze out Final dark matter density: Wh2 ~ 1/<sv> Thermally avaraged cross section of all annihilation channels WMAP: 0.094 < Wh2 < 0.129 @ 2s WHEPP-9 Bhubaneswar

  7. Collider tests of WIMPs • Generic WIMP signature at LHC: jets (+leptons) + ETmiss • Great for discovery; resolving the nature of the WIMP however not obvious • Need precision measurements of masses, couplings, quantum numbers, .... → ILC LHC WMAP ILC WHEPP-9 Bhubaneswar

  8. Neutralino-LSP in the MSSM WHEPP-9 Bhubaneswar

  9. Minimal supersymmetric model • SUSY = Symmetry between fermions and bosons • If R-parity is conserved the lightest SUSY particle (LSP) is stable → LSP as cold dark matter candidate mix to 2 charginos + 4 neutralinos WHEPP-9 Bhubaneswar

  10. Neutralino system Gauginos Higgsinos Neutralino mass eigenstates → LSP WHEPP-9 Bhubaneswar

  11. Neutralino relic density Specific mechanisms to get relic density in agreement with WMAP 0.094 < Wh2 < 0.129 puts strong bounds on the parameter space WHEPP-9 Bhubaneswar

  12. mSUGRA parameter space • GUT-scale boundary conditions: m0, m1/2, A0 [plus tanb, sgn(m)] • 4 regions with right Wh2 • bulk (excl. by mh from LEP) • co-annihilation • Higgs funnel (tanb ~ 50) • focus point (higgsino scenario) WHEPP-9 Bhubaneswar

  13. Prediction of <sv> from colliders:What do we need to measure? • LSP mass and decomposition bino, wino, higgsino admixture • Sfermion masses (bulk, coannhilation) or at least lower limits on them • Higgs masses and widths: h,H,A • tanb With which precision? WHEPP-9 Bhubaneswar

  14. What do we need to measure with which precision:Coannihilation with staus, DM<10 GeV ~ • DM(stau-LSP) to 1 GeV • Precise sparticle mixings • Difficult at LHC; soft tau´s! • Achievable at ILC: • Stau mass at threshold Bambade et al, hep-ph/040601 • Stau and Slepton masses Martyn, hep-ph/0408226 • Stau-neutralino mass difference Khotilovitch et al, hep-ph/0503165 Beam polarization essential! [Allanach et al, hep-ph/0410091] WHEPP-9 Bhubaneswar

  15. Golden decay chain at LHC • Stau coannihilation region: leptons will mostly be taus • Small stau-LSP mass difference DM ≤ 10 GeV leads to soft t´s • Difficult to measure mttkinematic endpoint for mass determination WHEPP-9 Bhubaneswar

  16. Determination of slepton and LSP massesat the ILC [Martyn, hep-ph/0408226] WHEPP-9 Bhubaneswar

  17. Determination of the neutralino systemLHC+ILC case study for SPS1a:light -inos at ILC; neutralino4 at LHC [Desch et al., hep-ph/0312069] WHEPP-9 Bhubaneswar

  18. What do we need to measure with which precision:Higgsino LSP, m ~ M1,2 Fractional accuracies needed • Annihilation into WW and ZZ via t-channel c± or c0 • Rate determined by higgsino fraction fH=N132+N142 • 1% precision on M1 and m • All neutralinos/charginos; mixing via pol. e+e- Xsections • LHC: discovery via 3-body gluino decays / Drell-Yang [Allanach et al, hep-ph/0410091] WHEPP-9 Bhubaneswar

  19. Scan of focus point scenario, LCC2 m0 = 3280 GeV, m1/2 = 300 GeV, A0 = 0, tanb = 10 [J.L. Feng et al., ALCPG] WHEPP-9 Bhubaneswar

  20. What do we need to measure with which precision:Annihilation through Higgs Fractional accuracies needed • Mainly cc→ A →bb • CP even H exchange is P-wave suppressed • mcandmAto 2%-2‰ • (mA-2mc) and m to 5% • A width to 10% g(Acc)~N132-N142, g(Abb)~hb, .... [Allanach et al, hep-ph/0410091] WHEPP-9 Bhubaneswar

  21. Influence of mA on evaluation of Wh2 → large uncertainty if lower limit on mA is not >> 2 mLSP [Birkedal et al, hep-ph/0507214] WHEPP-9 Bhubaneswar

  22. e+e_→ HA • A not produced in Higgs-Strahlung, need e+e_ → HA • H,A masses to ~1 GeV; limitation by kinematics! • Widths only to 20%-30% • Production in gg mode can help a lot [Heinemeyer et al., hep-ph/0511332] WHEPP-9 Bhubaneswar

  23. Heavy Higgses at LHC H/A in cascade decays WHEPP-9 Bhubaneswar

  24. For a precise prediction of Wh2 compatible with WMAP acurracy we need precision measurements of most of the SUSY spectrum → LHC/ILC synergy WHEPP-9 Bhubaneswar

  25. So far considered CP conserving MSSM What if CP is violated? [we actually need new sources of CP violation beyond the SM for baryogenesis] WHEPP-9 Bhubaneswar

  26. CP violation • In the general MSSM, gaugino and higgsino mass parameters and trilinear couplings can be complex: • Important influence on sparticle production and decay rates → Expect similar influence on <sv> NB1: M2 can also be complex, but its phase can be rotated away. NB2: CPV phases are strongly constrained by dipole moments; we set fm=0 and assume very heavy 1st+2nd generation sfermions WHEPP-9 Bhubaneswar

  27. CP violation: Higgs sector • Non-zero phases induce CP violation in the Higgs sector through loops → mixing of h,H,A: • Couplings to neutralinos: WHEPP-9 Bhubaneswar

  28. Previous studiesof neutralino relic density with CP violation WHEPP-9 Bhubaneswar

  29. CPV analysis with micrOMEGAs M1 = 150, M2 = 300, At = 1200 GeV, tanb = 5 masses of 3rd gen: 500 GeV, 1st+2nd gen: 10 TeV • bino-like LSP, m ~ 150 GeV • Wh2 < 0.129 needs annihilation through Higgs • Scenario 1: m = 500 GeV → small mixingin Higgs sector • Scenario 2: m = 1 TeV → large mixing in Higgs sector Higgs mixing ~ Im(Atm) [Belanger, Boudjema, SK, Pukhov, Semenov, in: LesHouches‘05] WHEPP-9 Bhubaneswar

  30. CPV with micrOMEGAs WHEPP-9 Bhubaneswar

  31. Scenario 2 Key parameter is distance from pole WHEPP-9 Bhubaneswar

  32. Recall Higgs funnels in mSUGRA mA= WHEPP-9 Bhubaneswar

  33. Higgs funnel with large Higgs CP-mixing h2 h3 h3 h3 Green bands: 0.094<Wh2<0.129 dmi = mhi - 2mLSP, i=2,3 WHEPP-9 Bhubaneswar

  34. Higgs funnel with large Higgs CP-mixing h2 h3 h3 h3 Green bands: 0.094<Wh2<0.129 WHEPP-9 Bhubaneswar

  35. Higgs funnel with large Higgs CP-mixing h3 Green bands: 0.094<Wh2<0.129 dmi = mhi - 2mLSP, i=2,3 WHEPP-9 Bhubaneswar

  36. CP violation • is a very interesting option • can have order-of-magnitude effect on Wh2 • needs to be tested precisely • However: computation of annihilation cross sections at only at tree level; radiative corrections may be sizeable! WHEPP-9 Bhubaneswar

  37. Assume we have found SUSY with a neutralino LSP and made very precise measurements of all relevant parameters: What if the inferred Wh2 is too high? WHEPP-9 Bhubaneswar

  38. Solution 1:Dark matter is superWIMP e.g. gravitino or axino WHEPP-9 Bhubaneswar

  39. Solution 2:R-parity is violated after all • RPV on long time scales • Late decays of neutralino LSP reduce the number density; actual CDM is something else • Very hard to test at colliders • Astrophysics constraints? WHEPP-9 Bhubaneswar

  40. Solution 3:Cosmological assumptions are wrong • Our picture of dark matter as a thermal relic from the big bang may be to simple • The early Universe may have evolved differently • .... • .... • .... WHEPP-9 Bhubaneswar

  41. Conclusions: • We expect new physics beyond the SM • to show up at the TeV energy scale • to provide the dark matter of the Universe • Using the example of neutralino dark matter I have shown that precison measurements at both LHC+ILC are necessary to pin down the nature and properties of the dark matter Wh2 ~ 1/<sv> from LHC/ILC ↔ WMAP acurracy • Direct detection in addition to pin down DM WHEPP-9 Bhubaneswar

  42. LHC WMAP ILC Accuracies of determining the LSP mass and its relic density [Alexander et al., hep-ph/0507214] WHEPP-9 Bhubaneswar

  43. What if only part of the spectrum is accessible? • Part of the spectrum may escape detection • Too heavy sparticles, only limits on masses • Not enough sensitivity, e.g. H,A • Only LHC data available, .... • Model assumptions, fits of specific models, etc, to obtain testable predicions [or to test models] • Famous example: Fit of mSUGRA to LHC data at SPS1a Need precise predictionswithin models of SUSY breaking WHEPP-9 Bhubaneswar

  44. Comparison of SUSY spectrum codes • Computation of SUSY spectrum with 4 state-of-the-art SUSY codes: Isjet,Softsusy,Spheno,Suspect 2loop RGEs + 1loop threshold corrections, 1loop corr. to Yukawa couplings, ... • Computation of relic desity with micrOMEGAs • Mapped mSUGRA parameter space for • differences in predictions of Wh2 • differences in WMAP exclusions due to spectrum uncertainties [Belanger, SK, Pukhov, hep-ph/0502079] WHEPP-9 Bhubaneswar

  45. Uncertainties from sparticle mass predictions O(1%) moderate parameters, stau coannihilation Stau-LSP mass difference! d(DM)~1 GeV →dW~10% Contours of Wh2=0.129 [Belanger, SK, Pukhov, hep-ph/0502079] WHEPP-9 Bhubaneswar

  46. Uncertainties from sparticle mass predictions: large tanb and the Higgs funnel [Belanger, SK, Pukhov, hep-ph/0502079] WHEPP-9 Bhubaneswar

  47. There is need to improve computations and tools in order to match acurracies required by WMAP/Planck Improvements in spectrum computations are discussed in [Baer, Ferrandis, SK, Porod, hep-ph/0511123] WHEPP-9 Bhubaneswar

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