Cosmology/DM - I. Konstantin Matchev

Transcription

1 Cosmology/DM - I Konstantin Matchev

2 What Do We Do? Trying to answer the really big questions: 1. What is the Universe made of? Can the laws of Physics be unified? 16. What is the cause of the terrible twos? Says who? How about DOE/NSF (he who pays the piper orders the tune )

3 The 9 Big Questions Are there undiscovered principles of Nature: new symmetries, new physical laws? How can we solve the mystery of dark energy? Are there extra dimensions of space? Do all forces become one? Why are there so many kinds of particles? What is dark matter? How can we make it in the lab? What are neutrinos telling us? How did the universe come to be? What happened to the antimatter?

4 The need for new physics BSM Heavy elements 0.03%

5 DARK MATTER Known DM properties Stable Non-baryonic Cold DM: precise, unambiguous evidence for new particles (physics BSM)

6 BSM Theory Cookbook Two approaches: A: Take the SM and modify something. B: Ask your advisor how to do A. The Standard Model is a Lorentz-invariant gauge theory based on SU(3)xSU()xU(1) of mostly fermions but also one Higgs in d=4 As a rule, we expect new particles

7 Dark Matter Cookbook Invent a model with new particles Supersymmetry Universal Extra Dimensions Invent a symmetry which guarantees that at least one of them (the lightest) is stable Fudge model parameters until the dark matter particle is neutral Calculate the dark matter relic density Use a computer program, e.g. MicrOMEGAs Fudge model parameters until you get the correct relic abundance If it works, don t forget to write a paper

8 Outline of the lectures All lecture materials are on the web: Yesterday: became familiar with MicrOMEGAs Implement the New Minimal Standard Model (Davoudiasl, Kitano, Li, Murayama 004) 1 1 k h 4 μ L S = μ S S m S S H S S 4! Today: discuss several new physics models and their respective dark matter candidates concentrate on WIMPs Later today: discuss how collider and astro experiments can determine DM properties discriminate between alternative models Homework exercises throughout today s lectures

9 Useful references Jungman, Kamionkowski, Griest, hep-ph/ Bergstrom, hep-ph/00016 Bertone, Hooper, Silk, hep-ph/ Feng, hep-ph/ Baltz, Battaglia, Peskin, Wizansky, hep-ph/ Murayama, [hep-ph] Peskin, [hep-ph]

10 DARK MATTER CANDIDATES There are many candidates Masses and interaction strengths span many, many orders of magnitude But not all are equally motivated. Focus on: WIMPs: natural thermal relics Dark Matter Scientific Assessment Group, U.S. DOE/NSF/NASA HEPAP/AAAC Subpanel (007)

11 Thermal relic abundance - I At early times, the DM particles χ and SM particles X are in thermal equilibrium χχ XX Freeze-out described by the Boltzmann equation 3 Hn χ dn χ = 3 Hn χ σ A υ nχ neq dt accounts for dilution due to Hubble expansion σ A υ nχ describes depletion due to σ A υ neq describes resupply due to χχ XX χχ XX

12 Thermal relic abundance - II σ A is the total DM annihilation cross-section σ A σ χχ XX a bυ ο υ 4 X Notice that we do not know the specific final states The a-term is the one relevant for indirect detection (ongoing DM annihilations in the galactic halo) Approximate analytic solution 10 9 GeV 1 x F 1 χh = M Pl g x F a 3 b/ x F mχ 45 g m χ M Pl a 6 b/ x F x F =ln c 5 3 TF 8 π g x F x F

13 What does WMAP tell us? 3 unknowns: χ h, σ A=a bυ, m χ ; 1constraint 1. Thermal relics make up all of the DM: χ h =0.1 α. Thermal relics are WIMPs: σ A =k mχ HEPAP LHC/ILC Subpanel (006) [band width from k = 0.5, S and P wave]

14 Supersymmetry Extra dimension, but fermionic (θ s anticommute) μ μ α μ μ α Φ x, θ = x ψ x θ α F x θ θ α SUSY relates particles and superpartners ψ The SM particles and their superpartners have Spins differing by ½ Identical couplings Introduce negative R-parity for superpartners Forbids dangerous interactions allowing proton decay Is it overrated? (do the HW in SUSY lecture1) No tree-level contributions to precision EW data Makes the lightest superpartner stable (dark matter!)

15 DM CANDIDATES IN MSSM Spin U(1) M1 SU() M Up-type µ Down-type µ mν m3/ G graviton 3/ G gravitino Neutralinos: {χ χ1, χ, χ3, χ4} 1 B W 00 1/ B Bino W 0 Wino 0 H u H d ν Higgsino Hu Higgsino Hdd ν sneutrino PS. Beyond the MSSM: ν R, Z ', S,...

16 Neutralino spectrum M1 0 M Z c β s W M Z s β s W 0 M M Z c β c W M Z s β c W M Z c β s W M Z c β c W 0 μ M Z s β s W M Z s β c W μ 0 c W cosθ W s W sinθ W c β cos β s β sin β 0 0 Lightest neutralino: χ 1 =α1 B α W α 3 H d α 4 H u Mass eigenstates: { M 1, M, μ, μ } Consider the three limiting cases 0 Pure Bino: M 1 << M, μ χ 1 B 0 W 0 M << M, μ χ Pure Wino: H 0 ± H 0 / μ << M, M χ u d Pure Higgsino: 1 1

17 Dark matter codes for SUSY Public Neutdriver (Jungman) DarkSUSY (Gondolo, Edsjo, Ullio, Bergstrom, Baltz) MicrOMEGAs (Belanger, Boudjema, Pukhov, Semenov) Can also handle generic nonsusy models Includes all relevant processes User-friendly, based on CalcHEP Private IsaRED (Baer, Balazs, Belyaev, Brhlik) SSARD (Ellis, Falk, Olive) Drees/Nojiri Roszkowski Arnowitt/Nath Lahanas/Nanopoluos Bottino/Fornengo Use your favorite computer code to check and analyze the following examples

18 Bino dark matter Possible channels Bino annihilation is suppressed No s-channel diagrams 1/M suppression in t-channel No gauge boson final states Helicity suppression for fermion final states neutralinos are Majorana fermions => S=0 if s-wave, J=0 and helicity flip required on the fermion line π (recall decay) bυ >> a υ predominantly p-wave, but still suppression => Binos give too much dark matter, unless other sparticles are light -> upper limits on SUSY masses?

19 Wino dark matter Possible channels Unsuppressed annihilation to W pairs Cannot use threshold suppression m χ ~ M W light wino-like chargino Result: wino relic density too small, unless the wino is rather heavy HW: Assume all of the dark matter is pure winos. Use MicrOMEGAs to find the range of wino masses preferred by cosmology.

20 Higgsino dark matter Possible channels Unsuppressed annihilation to W and Z pairs Cannot use threshold suppression m χ ~ M W light higgsino-like chargino Result: higgsino relic density too small, unless the higgsino is rather heavy HW: Assume all of the dark matter is pure higgsinos. Use MicrOMEGAs to find the range of their masses preferred by cosmology.

21 Mixed neutralino dark matter Recap: Pure Bino gives too much dark matter Pure Wino gives too little dark matter Pure Higgsino gives too little dark matter How about mixed cases? Mixed Wino-Higgsino DM: M ~μ << M 1 Mixed Bino-Wino DM: M 1~ M << μ e.g. non-universal gaugino masses, rsugra Birkedal-Hansen,Nelson 001 Mixed Bino-Higgsino DM: M 1~μ << M E.g. focus point SUSY Feng,KM,Wilczek 000

22 The exceptional cases Coannihilations: requires other particles to be degenerate with the LSP at the level of ΔM T F ~m χ /5 Resonances ( funnels ): h, H/A or Z. α α σ A~ σ A~ mχ Γ Re s

23 Minimal Supergravity (MSUGRA) A simple and popular model: universal BC at MGUT ΩDM stringently constrains the model Bulk region Too much dark matter Feng, Matchev, Wilczek (000) Co-annihilation region Focus point region Yellow: pre-wmap Red: post-wmap Cosmology highlights certain regions, detection strategies

24 MSSM soft SUSY breaking masses: RGE evolution Gaugino universality: M 1 : M : M 3~1:: 6 LSP is not wino EWSB condition: μ 1 ~ m Hu M Z μ is typically large

25 Sneutrino dark matter Left-handed: direct detection rules it out as a dominant DM component Falk,Olive,Srednicki 1994 HW: prove it using MicrOMEGAs Right-handed? Needs new interactions to thermalize and freeze out with the correct abundance e.g. U(1) gauge interaction Lee,KM,Nasri 007

26 Universal Extra Dimensions Appelquist,Cheng,Dobrescu 000 Bosonic extra dimension with a new coordinate y ny ny n μ Φ x, y = x x cos χ x sin R R n=1 An infinite tower of Kaluza-Klein (KK) partners for all Standard Model particles The SM particles and their KK partners have μ μ n μ Identical spins Identical couplings Automatic KK-parity for KK partners Makes the lightest KK partner stable (dark matter!)

27 Kaluza-Klein masses In d=4 we have E p x p y p z = m With one extra dimension (u) we get E p p p p =m x y z u π Recall particle-wave duality p u = λ Periodicity implies quantization of momentum π R λ = n π n n pu = = π R R KK modes: particles with momentum in the ED: n E p p p =m + p =m + R x y z u

28 UED Kaluza-Klein mass spectrum KK masses at tree-level Cheng,KM,Schmaltz 00 Several stable, charged KK particles KK masses at one-loop Cheng,KM,Schmaltz 00 Only the LKP is stable. The LKP is neutral (DM!)

29 KK dark matter Relic density calculation involved, many coannihilations Servant,Tait 00 Burnell,Kribs 005 Kong,KM 005 Direct detection Lower bound on the rate Cheng,Feng,KM 00

30 UED in D=6 extra dimensions Gauge bosons have extra polarizations One is eaten as in D=5 The other appears as a scalar in D=4 The LKP is now the scalar KK hypercharge boson Dobrescu,Kong,Mahbubani 007 Dobrescu,Hooper,Kong,Mahbubani 007

31 mass SUSY or ED or something else? Spins differ by 1/ Higher levels no same as SM yes same as SM no

32 earth, air, fire, water baryons, νs, dark matter, dark energy