Supersymmetric Dark Matter Shufang Su • U. of Arizona K. Olive, astro-ph/0301505

Composition of the Universe - We know how much, but no idea what it is. » 0.7 Dark Energy , quintenssence,… » 0.02 baryon 0.1 - 0.3 Non-baryonic dark matter Baryonic dark matter (lum» 0.003)  Hot dark matter: Neutrino  Cold dark matter WIMP axions  Other possibilities self-annihilating DM self-interacting DM warm DM fuzzy CDM … S. Su Dark Matter

WIMP CDM requirements  Stable lifetime ¸ 10 Gyr  Non-baryonic  Neutral: color (strong interaction) and electric strong upper limits on the abundance of anomalously heavy isotopes  Cold: non-relativistic  Yield correct density WIMP weak interacting:  » 0.01, mW » 100 GeV   » 0.1 S. Su Dark Matter

Not for cosmology observations Standard Model - I II III Quarks u c t d s b SM is a very successful theoretical framework that describes all experimental observations to date Leptons e   e   Not for cosmology observations Dark Matter Cosmology constant Baryon asymmetry … Gauge boson (force carrier)  W§,Z g electro -magnetic » 0.01 weak » 0.03 strong » 0.1 =g2/4 Higgs H S. Su Dark Matter

Standard Model No good candidates for CDM in SM I II III Quarks u c t - I II III Quarks u c t d s b CDM requirements  Stable Leptons e   e    Non-baryonic  Neutral  Cold  Correct density Gauge boson (force carrier)  W§,Z g Higgs H No good candidates for CDM in SM S. Su Dark Matter

Supersymmetry  SM is an effective theory below some energy scale  -  SM is an effective theory below some energy scale  Hierarchy problem: MEW100 GeV , Mplank 1019 GeV ? Naturalness problem: mass of a fundamental scalar (like Higgs) receive huge quantum corrections: (mH2)physical  (mH2)0 + 2 (100 GeV)2 H - 2 H -(1019 GeV)2 precise cancellation up to 1034 order (1019 GeV)2  Supersymmetry SM particle superpartner Spin differ by 1/2 Naturalness  ms-particle » O(100-1000) GeV S. Su Dark Matter

Gauge Coupling Unification - SM SUSY S. Su Dark Matter

Minimal Supersymmetric Standard Model (MSSM) - Spin differ by 1/2 SM particle superpartner » » » Squarks u c t d s b CDM requirements » » »  Stable » » » sleptons e   e    Non-baryonic  Neutral » » »  Cold » » » » m > 45 GeV Gauginos B0 W§,W0 g  Correct density » » » » weak interaction Higgsino (Hu+,Hu0) , (Hd0, Hd-) S. Su Dark Matter

MSSM DM Candidates Possible DM candidates  Stable ? - Possible DM candidates sneutrino  neutralino (B0,W0,Hd0,Hu0) ! i0 ~ ~ ~ ~ ~  Stable ? General MSSM, including B,L-violating operators - dangerous  introduce proton decay p ! K+ R-parity SM particle: even + superparticle: odd - no proton decay lightest supersymmetric particle (LSP) stable LSP  SM particle, LSP  super particle Good candidate of DM: could be  or 10 d u P K+ ~ s -  odd ~ S. Su Dark Matter

Sneutrino Dark Matter rapid annihilation, hAvi large - ~  Z /l/q ~   /l ~  W/Z f rapid annihilation, hAvi large light sneutrino: 45-200 GeV  low abundance heavy sneutrino: 550 – 2300 GeV  0.1    1 disfavored on theoretical ground excluded by nuclear recoil direct detection: m ¸ 20 TeV ~ Sneutrino CDM in MSSM is excluded S. Su Dark Matter

Neutralino ~ ~ ~ ~ B0, W0, Hd0, Hu0 Properties fermion neutral - ~ ~ ~ ~ B0, W0, Hd0, Hu0 Superpartner of gauge bosons Superpartner of Higgs bosons Properties fermion neutral heavy: m > 45 GeV (B0, W0, Hd0, Hu0)  neutralinos i0, i=1…4 mass eigenstates Interactions: weak interacting / gauge coupling ~ ~ ~ ~ f  ~ H  W,Z  S. Su Dark Matter

Lightest Neutralino CDM - Now let us focus on neutralino as a candidate for CDM Neutralino mass matrix Input parameter: M1, M2, , tan i0=i B0+ i W0+i Hd0 +i Hu0 , m1 m2  m3  m4 , 1 being LSP ~ For small mixing: mZ ¿ M1, M2,  M1< M2, ||: B0 Bino-LSP M2< M1, ||: W0 Wino-LSP ||< M1, M2: Hu0 § Hd0 Higgsino-LSP ~ S. Su Dark Matter

MSSM Parameters Interactions involve the whole set of MSSM parameters - Interactions involve the whole set of MSSM parameters > 100 new parameters (SM: 19 parameters) other experimental constraints LSP Simplest assumption (unification) CMSSM (constrained MSSM) m0 M1/2 A0 tan sign  GUT scale ||,b replaced by mZ, tan common scalar mass common gaugino mass common trilinear scalar Low energy MSSM parameters  S. Su Dark Matter

Relic Density Thermal relic density Decoupling: >H =nhvi ¼ H - Thermal relic density Decoupling: =nhvi ¼ H >H  ! X+Y early time n ¼ neq late time (n/s)today » (n/s)decoupling at freeze-out T » m/20 <H n/s Approximately, relic / 1/hvi S. Su Dark Matter

Neutralino Relic Density (I) - 10 f ~ 10 + W t-channel (dominate) absent for B0 ~ ~ 10 Z,H /l/q s-channel Important near pole m » mZ,H/2 ~ 10 Relic Density: =hAvi n » H <v> = a+bx+… x=T/m Special cases: Co-annihilation: mLSP ¼ mNLSP Annihilation near a pole: e.g. m » mZ,H/2 S. Su Dark Matter

Neutralino Relic Density (II) - No EWSB 0.1  h2  0.3 m » mA.H/2 CMSSM Focus point m=mZ,h/2 Co-annihilation 10-l ~ bulk stau LSP S. Su Dark Matter

Phenomenological Constraints - Other constraints Higgs mass mh > 114.4 GeV b ! s  : » 10-4 exclude small m1/2 important for  <0 muon g-2 th-exp=(26 § 16)£ 10-10 b s  muon g-2 me=99GeV ~ m= mZ,h/2 region already excluded b ! s  S. Su Dark Matter

Bulk region and -l coannihilation region ~ - m » m +X ! +Y in equilibrium  decays into  eventually Co-annihilation:, ,  ~ co-annihilation mh bulk if ignore co-annihilation hvi » 1/m2,  / m/hvi  upper bound on m mB » 200 GeV ~ S. Su Dark Matter

hvi » 1/(4m2 – mA,H2)2 too big Funnel-Like Region - ~ 10 A,H /l/q Large tan : m » mA,H/2 A,H: heavy Higgses SM: h0 MSSM: h0,H0,A,H§  / 1/hvi hvi » 1/(4m2 – mA,H2)2 too big   too small S. Su Dark Matter

Focus Point Region (100 GeV)2 conventional wisdom focus point - (100 GeV)2 conventional wisdom focus point naturalness  m0, M1/2, ||  TeV m0 a few TeV , natural m0 term negligible m0 term not negligible || À M1 || » M1 DM Bino-like: 10 ¼ B0 DM Bino-Higgsino mixture Co-annihilation, funnel and focus point regions are very fine-tuned Highly depend on the other input parameters ~ S. Su Dark Matter

Direct Detection of DM - Direct detection via neutralino-nucleon scattering DM low velocity, non-relativistic Spin-dependent:  i  q i q Mspin / pq h Spi/ JN + nq h Sni/ JN Spin-independent:   q mq q / mW Mscalar / Z fp+ (A-Z) fn - Bino DM: no diagram 1 require small m0 Bino-Higgsino DM large m0 detectable ,Z / 1/mq2 ~ S. Su Dark Matter

Neutralino-Nucleon Scattering (II) 2 £ 10-10 pb  SI  6 £ 10-8 pb 2 £ 10-7 pb  SD  10-5 pb S. Su Dark Matter

DAMA and CDMS - CDMS DAMA DAMA finds signal in annual modulation as earth passes through WIMP wind CDMS and Edelweiss excludes much of the favored region Edelweiss NUHM CMSSM pb = 10-36 cm2 S. Su Dark Matter

Indirect Detection - DM annihilation products from the Sun, Earth, galaxy require hard annihilation products (not good for Bino DM)  from the core of the Earth and Sun e+ from the local solar neighborhood  from the Galactic center   Under-ice, underwater neutrino telescopes Anti-matter/ anti-particle experiments Atmospheric Cherenkov telescopes, space-based  ray detectors S. Su Dark Matter

Comparison of pre-LHC SUSY Searches DM searches are complementary to collider searches When combined, entire cosmologically attractive region will be explored before LHC ( » 2007 ) S. Su Dark Matter

Conclusion DM is the one of the strongest phenomenological - DM is the one of the strongest phenomenological motivation for new physics Fruitful interplay of particle physics, cosmology, and astrophysics A fascinating time: we know how much, but have no idea what it is Many, many experiments MSSM neutralino LSP is a good candidate for CDM In SUSY, DM searches are promising, highly complementary to collider searches S. Su Dark Matter