Dark Matter: A Mini Review Jin Min Yang 杨 金 民 中国科学院理论物理研究所 2008.7.23 Hong Kong

Outline Evidence of Dark Matter Candidates of Dark Matter Experiments for Dark Matter SUSY Dark Matter Outlook

1、 Evidence of Dark Matter Galactic clusters: need DM to bind them (1930s, Zwicky) Galaxy rotation curves: need a diffuse halo of DM (1970s, Rubin &Ford) Gravity lensing: strong and weak lensing show DM in universe Hot gas in clusters: need DM to bind the hot gas CMB: CMB power spectrum show composition of universe (WMAP) Large scale structure formation: a universe composed of CDM and DE BBN: light elements abundances agree with observation if nB/n ~ 610-10 (imply baryon mass density ~ 4 ) Supernovae probe: Hubble diagram indicate DM and DE in universe Colliding clusters: observation of colliding clusters from bullet cluster

  0.3 GeV/cm3 V  220 km/s

candidates What we know about DM so far ? neutral cold (part of it can be warm) weak interaction (with itself and with ordinary matter) profile (around us 0.3GeV/cm3 V  220 km/s) Identity of DM particle ? candidates

2、Candidates of Dark Matter Q-balls: topological solitons in QFT (Coleman, Kusenko) Neutrinos: sterile (Kusenko, 2006) Black hole remnants: tiny BHs produced in early universe Wimpzillas: massive beasts (Kolb et al) Axions: Peccei-Quinn solution to strong CP WIMPs: lightest neutralino in SUSY with R-parity lightest KK excitations in EDT with KK-parity lightest T-odd particle in LHT with T-parity SuperWIMPs: gravitino in SUSY with R-parity axino—fermionic partner of axion lightest KK graviton in EDT

Why WIMP is popular and favored ? (1) naturally predicted in new physics models (SUSY, Extra-dimension, LHT) lightest neutralino in SUSY with R-parity lightest KK excitations in extra-dimension lightest T-odd particle in LHT with T-parity (2) naturally give the correct relic density of DM

Universe cools: n=nEQe-m/T WIMP correct relic density of DM Thermal equilibrium   ff Universe cools: n=nEQe-m/T 10-34 秒 Freeze out ~ 0.1 BBN 1 秒 1013 秒 1018 秒

Note: so far all DM information is from astro observation ! (gravity effects of DM) Nature (identity & property) of DM particle experiments

3、Experiments for Dark Matter 3.1 Astrophysical experiments direct detection c c p e+ n g _ indirect detection land-based high altitude space-based 3.2 Collider experiments (LHC, ILC)

3.1 Astrophysical experiments (a) direct detection

(b) indirect detection (anti-particle)

(c) indirect detection (photon) ARGO-YBJ W. de Boer

(d) indirect detection (neutrino)

3.2 Collider study of dark matter Tevatron (now) LHC (2008) ILC (???)    model-dependent study model-independent study (possible) model-dependent study Birkel,Matchev,Perelstein, 2004

4. SUSY Dark Matter

neutralino (WIMP) LSP gravitino (SuperWIMP)

4.1 Neutralino (WIMP) Dark Matter (a) Allowed parameter space: Baer,Tata (2008)

(b) Astrophysical expts: Baer,Tata (2008)

(c) Collider expts (LHC, ILC): Baer,Tata (2008) LHC Baltz et al (2006)

(d) Collider + Astrophysical expts: Baer,Tata (2008) Baer, et al (2004)

4.2 Gravitino (SuperWIMP) Dark Matter (1) Interaction: (gaugino & gauge boson) (fermions) Suppressed by  E/M* (extremely weak !) (2) Relic density: (thermal) (late-decay of NLSP) Weinberg (1982) Cyburt, Ellis, Fields, Olive (2003) Kawasaki, Kohri, Moroi (2005) Feng, Rajaraman, Takayama, Su (2003)

(3) Astrophysical expts: Null results ! (due to extremely weak interaction) (4) Collider expts: Detect NLSP (meta-stable) NLSP (stau) SM particle LHC Hamaguchi, kuno, Nakaya, Nojiri (2004) Feng, Smith (2004)

5. Outlook Collider Experiments WIMP Property

LHC (“best case scenario”) ILC LHC (“best case scenario”) Planck (~2010) WMAP (current) LCC1 Battaglia (2005)

谢谢！