Katherine Freese Michigan Center for Theoretical Physics WIMP searches EXCITING TIMES

• We made WIMP proposals twenty years ago: • It is coming to fruition! • My personal prediction: one of the anomalous results is right and we will know very soon. LHC-Making DM Coming Soon (We hope) Supersymmetric Particles in LHC

• Signature: missing energy when SUSY particle is created and some energy leaves the detector • Problem with identification: degeneracy of interpretation • SUSY can be found, but, you still don’t know how long the particle lives: fractions of a second to leave detector or the age of the universe if it is • Proof that the dark matter has been found requires astrophysical particles to be found Direct Detection of WIMP dark matter A WIMP in the Galaxy travels through our detectors. It hits a nucleus, and deposits a tiny amount of energy. The nucleus recoils, and we detect this energy deposit.

Expected Rate: less than one count/kg/day! Event rate

(number of events)/(kg of detector)/(keV of recoil energy) dR N dσ = ∫ T × × nv f (v,t)d 3v dE MT dE ρσ F 2 (q) f (v,t) = 0 d 3v 2mµ2 ∫v> ME / 2µ 2 v € A2µ2 Spin-independent σ 0 = 2 σ p € µp 4µ2 2 Spin-dependent σ = S G + S G 0 π p p n n €

€ From DM Tools Website Many claims/hints of WIMP dark matter detection: how can we be sure?

• 1) The DAMA annual modulation • 2) The HEAT, PAMELA, and ATIC positron excess • 3) Gamma-rays from Galactic Center • 4) WMAP Haze HAS DARK MATTER BEEN DISCOVERED? The DAMA Annual Modulation DAMA annual modulation Drukier, Freese, and Spergel (PRD 1986); Freese, Frieman, and Gould (PRD 1988) Bernabei et al 2003

Data do show a 8σ modulation WIMP interpretation??? DAMA/LIBRA (April 17, 2008) 8 sigma Can the positive signal in DAMA be compatible with null results from other experiments?

Savage, Gelmini, Gondolo, and Freese, arxiv:0808:3607 (see also papers by Hooper and Zurek; Fairbairn and Schwetz; Chang, Pierce and Weiner 2008) DAMA: spin independent?

DAMA

CDMS

XENON

Small remaining region at 10 GeV WIMP mass DAMA and CDMS DAMA Spin- XENON dependent cross sections SUPER-K

Hooper and Zurek extended Super-K bounds Remaining window around 10 GeV.

Removing SuperK: WIMP mass up to 20 GeV allowed

Savage, Gelmini, Gondolo, Freese 0808:3607 New measurements of Sun’s velocity relative to Halo: 250 km/sec (not 220 km/sec)

CRESST • All curves move the left: • Remaining window moves to 7-8 GeV at 3 sigma (5-15 for SD) Savage, Freese, Gondolo, Spolyar 2009

To reconcile DAMA with null results from other experiements: • Popular theory: Direct Detection • In past two years, two orders of magnitude increase in sensitivity (the following results not included in our compatibility study): (i) CDMS (ii) XENON-10 (iii) ZEPLIN III New technology: liquid noble gases XENON, LUX, XMASS WARP (argon) DEAPCLEAN (argon and neon) New signals in direction detection 2010 • CDMS: Germanium (Berkeley, Stanford, Case Western, many others): two events • COGENT: low threshold germanium (Fermilab): one event at low WIMP mass, would be consistent with DAMA • Caveat: all statistically insignificant

Electron recoils

Nuclear Recoils n.b. if include 2008 data, this significance drops CDMS bounds

Inelastic Dark Matter COGENT low threshold germanium (Fermilab) Direct Detection • In past two years, two orders of magnitude increase in sensitivity: (i) CDMS (ii) XENON-10 (iii) ZEPLIN II and III New technology: liquid noble gases XENON, LUX, XMASS WARP (argon) DEAPCLEAN (argon and neon) DEAP/ Miniclean Eureka MAX, GeoDM

Slide from Pearl Sandick

RED OVALS: THOSE EXPTS THAT ARE CURRENTLY UNDERGROUND

Ultimate Searches?

XENON,LZ,MAX,GEODM EUREKA,DARWIN The HEAT and PAMELA Positron Excess The Indirect Detection of Dark Matter 1. WIMP Annihilation χ Typical final states include heavyχ fermions, gauge or Higgs bosons

2. Fragmentation/Decay W- Annihilation products decay and/or q fragment into combinations of W+ electrons, protons, deuterium, neutrinos and gamma-rays q e+ ν 3. Synchrotron and Inverse Compton π0 Relativistic electrons up-scatter starlight/ CMB to MeV-GeV energies, and emit p synchrotron photons via interactions with γ γ magnetic fields γ e+ Annihilation Products

• 1/3 electron/positrons • 1/3 gamma rays • 1/3 neutrinos • Typical particles have energies roughly 1/10 of the initial WIMP mass • All of these are detectable! Indirect Detection History

• Indirect Detection (Neutrinos) • Sun (Silk,Olive,Srednicki ‘85) • Earth (Freese ‘86; Krauss, Srednicki, Wilczek ‘86) • Indirect Detection (Gamma Rays, positrons) • Halo (Ellis, KF et al ‘87) • Galactic Center (Gondolo and Silk 2000) • Anomalous signals seen in HEAT (e+), HESS, CANGAROO, WMAP, EGRET, PAMELA. New Indirect Detection Results! (When it rains it pours) Pamela IceCube

FERMI

Dan Hooper - Direct and Indirect Searches For Particle Dark Matter Positron excess

• HEAT balloon found anomaly in cosmic ray positron flux • Explanation 1: dark matter annihilation • Explanation 2: we do not understand cosmic ray propagation

Baltz, Edsjo, Freese, Gondolo 2001

How to understand positron excess? • 0) Pulsars: the best bet? • 1) . Propagation of charged particles in the galaxy poorly understood. See Delahaye and Salati 08. • 2) proton background (misidentified as positrons), is known to rise with energy. PAMELA doesn’t identify each event (HEAT did) • 3) We happen to live in a hot spot of high dark matter density (boosted by at least factor 10) • 4) nonstandard WIMPs: e.g., nonthermal WIMPs; Kaluza Klein particles. MUST HAVE BOOSTED ANNIHILATION CROSS SECTION AND LEPTOPHILIC PRODUCTS • WHO KNOWS? ICECUBE/DEEPCORE will see neutrinos in five years if PAMELA anomaly is from DM Spolyar, Buckley, Freese, Hooper, Murayama 2009

String of phototubes in ice at South Pole

DEEPCORE: Swedish contribution Per-Olaf Hulth Gamma-rays from the Galactic Center

HESS Gamma-ray Data

Aharonian et al 2004 FERMI satellite

• NASA/DOE gamma-ray telescope

• Launched June 2008 Where To Look For Dark Matter With FERMI? The Galactic Halo The Galactic Center -High statistics -Brightest spot in the sky -Requires detailed model -Considerable astrophysical of galactic backgrounds backgrounds

Extragalactic Background -High statistics Individual Subhalos -potentially difficult to identify -Low backgrounds

Diemand, Kuhlen, Madau, APJ, astro-ph/0611370

Latest bounds from FERMI diffuse gamma-rays (from talk of Elliott Bloom in UCLA) Latest bounds from FERMI diffuse flux for two muon final state Dobler, Finkbeiner,Cholis, Slatyer, Weiner 2009 I. FERMI HAZE: controversial (gamma rays from Galactic Center)

II. See also model of Dan Hooper for yet another interpretation due to DM annihilation in FERMI Hooper/Goodenough model to explain FERMI data to GC Abazajian, Agrawal, Chacko claim to rule out PAMELA WMAP microwave emission interpreted as dark matter annihilation in inner galaxy? WMAP HAZE

Consistent with 100 GeV WIMPs.

Finkbeiner 2005; Hooper, Dobler 2007 Possible evidence for WIMP detection already now:

• The DAMA annual modulation • The HEAT/PAMELA positron excess • Gamma-rays from Galactic Center • WMAP haze

• Theorists are looking for models in which these results are consistent with one another (given an interpretation in terms of WIMPs) Upcoming Data: will the Dark Matter be found in 2010?

• LHC (find SUSY)

• Indirect Detection due to annihilation: • FERMI (gamma rays) • PAMELA (positrons) • ICECUBE (neutrinos) • GAPS (antideuterons)

• Direct Detection: many experiments • Directional Detection: see talk of D. Snowden-Ifft What will it take for us to believe DM has been found? • I. Direct detection: compatible signals in a variety of experiments made of different detector materials, and all the parties agree • 2. Indirect detection: annihilation signals in a variety of channels (neutrinos, gamma-rays, etc) all coming from the same source Sagittarius stream Freese, Gondolo, Newberg 2003 Directional detection with DRIFT-II THE END