Detection of Neutralino WIMP Yeong Gyun Kim (Korea Univ.) I.Evidence for Dark Matter II.Dark Matter Candidates III.Direct Detection of Neutralino WIMP IV.Indirect Detection : Neutrino Telescopes V.Conclusions decay and

What is Dark Matter ? : stuff that neither emits nor absorbs detectable EM radiation : the existence can be inferred by its gravitational effects on visible celestial body  Motion of Galaxies in Clusters  Galactic Rotation Curves  Gravitational Lensing  Temperature fluctuation of CMBR  …… I.Evidence for Dark Matter

 Observed the Coma cluster of galaxies in 1933: Fritz Zwicky ( )  Motions of galaxies in clusters  Found the galaxies move too fast to be confined in the cluster by the gravitational attraction of visible matter alone. The central 1Mpc of Coma cluster in optical Dark Matter in cluster

Galactic Rotation Curves Vera Rubin (1928-)  In 1970s, they found ‘flat’ rotation curves. Dark Matter in galaxy

Cosmic Microwave Background Anisotropies WMAP satellite

Matter/Energy density in the Universe Non-Baryonic Dark Matter Dark Energy (Cosmological constant) Baryonic Dark Matter

 Neutrinos  Axion  WIMPs (Weakly Interacting Massive Particles)  MACHOs (MAssive Compact Halo Objects)  Baryonic Dark Matter candidates  Non-Baryonic Dark Matter candidates ; Neutralinos, Kaluza-Klein states, ….  Wimpzillas ( superheavy DM )  …. …. ; Jupiter, brown dwarfs, white dwarfs, neutron stars, black hole….  Hydrogen gas, Dusts…. II. Dark Matter Candidates (what is Dark Matter made of ?)

Relic density of WIMPs Time evolution of the number density of WIMPs H : Hubble constant : thermally averaged annihilation cross section of WIMP WIMP : Weakly Interacting Massive Particle : equilibrium number density

Freeze out at If

Minimal Supersymmetric Standard Model (MSSM) SM fields plus an extra Higgs doublet and their superpartners SU(3) x SU(2) x U(1) gauge symmetry and Renormalizability R-parity conservation (to avoid fast proton decay) ( B: baryon number, L: lepton number S: spin ) = +1 for ordinary particles = -1 for their superpartners Soft Supersymmetry Breaking LSP is STABLE !

Neutralino mass matrix In the basis : Bino, Wino mass parameters : Higgsino mass parameter : ratio of vev of the two neutral Higgs  Lightest Neutralino = LSP in many cases (WIMP !! )

Neutralino Annihilation channels etc.

Overview of the allowed regions of mSUGRA parameter space by the Relic density of Neutralino WIMP 1. Bulk region : at low m0 and m1/2 : t-channel slepton exchange 2. Stau co-annihil. region : at low m0 where : neutralino-stau coannihilation 3. Focus point region : at large m0 where mu is small : a sigificant higgsino comp. 4. A-annihilation region : at largewhere (hep-ph/ , Battaglia et al.)

Local Dark Matter density Maxwellian velocity distribution Local Flux of Dark Matter III. Direct detection of Neutralino WIMP

Principles of WIMP detection Elastic scattering of a WIMP on a nucleus inside a detector The recoil energy of a nucleus with mass For This recoil can be detected in some ways : Electric charges released (ionization detector) Flashes of light produced (scintillation detector) Vibrations produced (phonon detector)

Experimental Results (CDMS collab. astro-ph/ )

Low energy effective Lagrangian for neutralino-quark int. scalar interaction spin-dep. interaction The other terms are velocity-dependent contributions and can be neglected in the non-relativistic limit for the direct detection. The axial vector currents are proportional to spin operators in the non-relativistic limit.

: the quark spin content of the nucleon  Spin-dependent Neutralino-Nucleus cross-section where (J : the spin of the nucleus) : the expectation values of the spin content of the nucleus : depends on the target nucleus for : reduced mass

 Scalar Neutralino-Nucleus cross-section whereA : the atomic weight, Z : the nuclear electric charge

In most instances, : the scalar (spin-independent) cross section scales with the atomic weight, in contrast to the spin-dependent cross section. The scalar interaction almost always dominates for nuclei with A > 30. : For, either interaction can dominate, depending on the SUSY parameters. : has predominantly spin-independent interactions.  vs.

 decays in MSSM In the Standard Model the decay proceeds through Z penguin and W exchange box diagrams. the decay is helicity suppressed due to angular momentum conservation. Current Experimental Limit (90% CL) (CDF) (D0)

In the MSSM (Babu,Kolda 2000) Fermion mass eigenstates can be different from the Higgs interaction eigenstates. This generates Higgs-mediated FCNCs.

 vs.  Both observables increase as increases.  Smaller Higgs masses give larger observable values.

Minimal Supergravity Model  Unification of the gauge couplings at GUT scale  Universal soft breaking parameters at GUT scale m : universal scalar mass M : universal gaugino mass A : universal trilinear coupling  Radiative EW symmetry breaking Free parameters ( m,M,A, )

These conditions imply that at EW scale Bino-like Heavy

mSUGRA model ( A=0 and m,M < 1TeV ) Higgs and sparticle mass and bounds included. (S.Baek, YGK, P.Ko 2004 )

mSUGRA model ( A=0 and m,M < 1 TeV ) Higgs and sparticle masses and bounds included. Required that Neutralino is LSP (S.Baek, YGK, P.Ko 2004 )

 Non-universal Higgs mass Model (NUHM)  Parameterize the non-universality in the Higgs sector at GUT scale  The above modifications of mSUGRA boundary cond. lead to the change of and at EW scale.

mSUGRANUHM

mSUGRANUHM

Non-Universal Higgs Mass Model

Non-Universal Higgs Mass Model

 A specific D-brane Model ( D.G. Cerdeno et al )  the gauge groups of the standard model come from different sets of Dp branes.  In this model, scalar masses are not completely universal and gaugino mass unificaion is relaxed.  the string scale is around GeV rather than GUT scale. Free parameters:

A D-brane Model

See D.G.Cerdeno’s talk this afternoon for more detailed analysis, including Non-universal scalar and gaugino masses

IV. Indirect detection of Neutralino WIMP ( Neutrino telescopes : SuperK, AMANDA, ANTARES, IceCube)  Neutralino WIMPs in the galactic halo can be captured by the SUN and Earth through Neutralino-nucleus scattering  The neutrino flux can be detected in neutrino telescopes via conversion  The accumulated Neutralino WIMPs annihilate into SM particles, which ultimately yields energetic neutrino flux

Super-K : Super Kamiokande detector 50,000 ton water Cherenkov detector, located in the Kamioka-Mozumi mine in Japan with 1000 m rock overburden. Set upper limits on WIMP-induced upward muon flux from the Sun and Earth etc. (~10^3 / km^2 yr)

AMANDA : Antiartic Muon and Neutrino Detector Array Uses 3 km thick ice layer at the geographical South Pole. A deep under-ice Cherenkov neutrino telescope. AMANDA-II detector is in operation with 677 PMTs at 19 strings since AMADA-II will be integrated to IceCube.

ANTARES : Astronomy with a Neutrino Telescope and Abyss environmental RESearch In construction of a 12-string detector in the Mediterranean Sea at 2400 m depth A deep underwater neutrino telescope.

 The number of Neutralino WIMP in the Sun (or Earth) : the capture rate of WIMPs onto the Sun (or Earth) : the total annihilation cross section times relative velocity per volume  The present annihilation rate (at =4.5 Gyr, age of solar system ) for When accretion is efficient, the annihilation rate depends on the capture rate C, but not on the annihilation cross section.

 The Capture rate C depends on the elastic scattering cross section of Neutralino with matter in the Sun (or Earth). The capture rate for the Earth primarily depends on the spin-independent DM scattering cross section. ( only a negligible fraction of the Earth’s mass is in nuclei with spin ) For the capture rate of the Sun, both spin-independent and spin-dependent DM scattering cross section can be important. ( spin-dependent interaction with hydrogen nuclei ) The neutrino-induced muon flux strongly depends on Neutralino-nucleus scattering cross section.

Muon Flux vs. mSUGRA model ( A=0 and m,M < 1TeV ) (S.Baek, YGK, P.Ko PRELIMINARY) from the Sunfrom the Earth

vs. (S.Baek, YGK, P.Ko PRELIMINARY) 

vs. (S.Baek, YGK, P.Ko PRELIMINARY)  in Non-Universal Higgs Model from the Sunfrom the Earth

Muon Flux vs. Non-Universal Higgs Mass Model from the Sunfrom the Earth (S.Baek, YGK, P.Ko PRELIMINARY)

Muon Flux vs. Non-Universal Higgs Mass Model from the Sunfrom the Earth (S.Baek, YGK, P.Ko PRELIMINARY)

Muon Flux vs. A D-brane Model (S.Baek, YGK, P.Ko PRELIMINARY) from the Earth from the Sun

V. Conclusions We considered the direct detection and indirect detection of neutralino WIMPs in the galactic halo, including the current upper bound of in mSUGRA, Non-Universal Higgs mass and a D-brane model. We have shown that current upper limit on the branching ratio puts strong constraint on the model parameter space which could lead to quite large spin-independent neutralino-proton scattering cross section and neutrino-induced muon flux from the Sun and Earth.