. . . . . . . . . Dark matter Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) Sep 8, 2012 Institute of High Energy Physics, CAS Work in progress with Xiao-Jun BI, Qi-Shu YAN and Peng-Fei YIN Dark matter and its implications at the LHC Conclusions . Numerical Calculation Motivation MC simulation . 1 / 21 . . . . . . . . . Zhao-Huan YU ( 余钊焕 )
. . . . . . . . . Dark matter Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) However, we hardly know its property. (galaxies, clusters, large scale struture, cosmological scale) Dark matter exists at various scales in the universe. Dark matter (DM) in the universe Conclusions Dark matter . Numerical Calculation Motivation MC simulation . 2 / 21 . . . . . . . . .
. . . . . . . . . Dark matter . MC simulation Motivation Numerical Calculation . Conclusions Dark matter detection Different kinds of DM detection Zhao-Huan YU (IHEP) Dark matter implications at the LHC Sep 8, 2012 3 / 21 . . . . . . . . .
. . . . . . . . . Dark matter detection Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) Work underground to reduce cosmic ray background (phonons, photons, ionization) Detect recoil signals of nuclei scattered by DM particles DM direct detection Conclusions Dark matter . Numerical Calculation Motivation MC simulation . 4 / 21 . . . . . . . . .
. . . . . . . . . Dark matter detection Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) [arXiv:1207.5988] Dark matter DM direct detection results 5 / 21 Conclusions Numerical Calculation . MC simulation Motivation . . . . . . . . . . -39 -39 -39 10 10 10 XENON100 (2012) DAMA/Na observed limit (90% CL) ] ] ] 2 2 2 10 10 10 -40 -40 -40 WIMP-Nucleon Cross Section [cm WIMP-Nucleon Cross Section [cm WIMP-Nucleon Cross Section [cm Expected limit of this run: CoGeNT ± 1 σ expected DAMA/I ± 2 σ expected -41 -41 -41 10 10 10 SIMPLE (2012) XENON10 (2011) COUPP (2012) CRESST-II (2012) 10 10 10 -42 -42 -42 ZEPLIN-III (2012) -43 -43 -43 XENON100 (2011) 10 10 10 EDELWEISS (2011/12) ) 1 1 0 / 0 1 ( 2 M S D C -44 -44 -44 10 10 10 -45 -45 -45 10 10 10 6 7 8 910 6 7 8 910 6 7 8 910 20 20 20 30 30 30 40 50 40 50 40 50 100 100 100 200 200 200 300 400 300 400 300 400 1000 1000 1000 2 2 2 WIMP Mass [GeV/c WIMP Mass [GeV/c WIMP Mass [GeV/c ] ] ]
. . . . . . . . . Conclusions Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) Detect products from dark mater annihilation or decay DM indirect detection Dark matter detection . Dark matter Numerical Calculation Motivation MC simulation . 6 / 21 . . . . . . . . .
. . . . . . . . . Dark matter . MC simulation Motivation Numerical Calculation . Conclusions Dark matter detection DM indirect detection experiments Zhao-Huan YU (IHEP) Dark matter implications at the LHC Sep 8, 2012 7 / 21 . . . . . . . . .
. . . . . . . . . Dark matter detection Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) Reach the most generic annihilation cross section of thermal produced dark Dark matter DM indirect detection results 8 / 21 Conclusions Numerical Calculation . MC simulation Motivation . . . . . . . . . . Upper limits, b ¯ b channel 10 -19 3 · 10 − 26 Draco Sextans Bootes I Fornax Ursa Major II 10 -20 Carina Sculptor Ursa Minor Coma Berenices Segue 1 Joint Likelihood, 10 dSphs WIMP cross section [cm 3 /s] 10 -21 10 -22 10 -23 10 -24 10 -25 10 -26 10 1 10 2 10 3 WIMP mass [GeV] Fermi-LAT γ -ray observation on 10 dwarf galaxies [PRL 107 241302 (2001)] matter ( ∼ 3 × 10 − 26 cm 3 s − 1 ).
. . . . . . . . . Dark matter Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) DM in collider detectors Dark matter detection Conclusions . Numerical Calculation Motivation MC simulation . 9 / 21 . . . . . . . . . How about DM particles? Missing! ( → / E T )
. . . . . . . . . Accompanied by many other Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) Monojet signal particle DM particle is the only new Maverick DM Various kinds of signal Complicated decay chain new particles Social DM Dark matter DM signature at the LHC Dark matter detection Conclusions . Numerical Calculation Motivation MC simulation . 10 / 21 . . . . . . . . .
. . . . . . . . . MadGraph 5 Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) Detector simulation PGS 4 Hadronization & decay Pythia 6.4 Parton shower parton-level event generation) Dark matter (Matrix element calculation & Hard process Monte Carlo simulation Conclusions . Numerical Calculation Motivation MC simulation . 11 / 21 . . . . . . . . . ⇑ ⇑ ⇓ ⇓
. . . . . . . . . Supersymmetry Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) LHC is considered: Dark matter A symmetry between fermions and bosons Supersymmetry (SUSY) 12 / 21 Conclusions Motivation Numerical Calculation . MC simulation . . . . . . . . . . e , µ , τ leptons ↔ sleptons e , ˜ ˜ µ , ˜ τ ν e , ν µ , ν τ neutrinos ↔ sneutrinos ν e , ˜ ˜ ν µ , ˜ ν τ ˜ c , ˜ b , ˜ d , u , s , c , b , t quarks ↔ squarks d , ˜ u , ˜ s , ˜ t g gluon ↔ gluino ˜ g W ± , H ± χ ± χ ± charged bosons ↔ charginos ˜ 1 , ˜ 2 B , W 3 , H 0 1 , H 0 χ 0 χ 0 χ 0 χ 0 neutral bosons ↔ neutralinos ˜ 1 , ˜ 2 , ˜ 3 , ˜ 2 4 χ 0 Most probably the lightest neutralino ˜ 1 is the lightest SUSY particle (LSP) and can be a well-motivated DM candidate . In order to solve the hierarchy problem of standard model, the stops ˜ t 1,2 need to be light enough. Thus ˜ t 1 is probably reachable in early LHC t ∗ searches. In the following work, the direct production of ˜ t 1 ˜ 1 pairs at the t ∗ pp → ˜ t 1 ˜ 1 + jets
. . . . . . . . . Supersymmetry Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) “If you cover the white then Weak scale SUSY is probably dead” R. Barbieri (ICHEP2012) Assuming some simplified models in which stops can be easily detected Current stop direct searches Conclusions Dark matter . Numerical Calculation Motivation MC simulation . 13 / 21 . . . . . . . . . Excluding stops up to ∼ 500GeV
. . . . . . . . . Dark matter (DM) Relic density Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) Need: coannihilates with the LSP. A way out: the next-to-lightest SUSY particle (NLSP) Dark matter 14 / 21 Dark Matter . . MC simulation Motivation Conclusions Numerical Calculation . . . . . . . . . Λ CDM model fitted by 7-year WMAP data: [Ap. J. Suppl. 192 , 16 (2011)] Ω CDM h 2 = 0.1109 , Ω baryon h 2 = 0.02258 , Ω Λ = 0.734 (Cold DM ∼ 21.1%, baryons ∼ 4.3%, dark energy ∼ 74.6%) For thermal produced DM, Ω CDM ∝ � σ ann v � − 1 . However, in SUSY models, the self-annihilation cross section σ ann of the χ 0 LSP neutralino ˜ 1 is generally not large enough to yield the observed relic density Ω CDM . m NLSP − m LSP ≲ 20% m LSP
. . . . . . . . . Conclusions Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) Dark matter Coannihilation scenarios 15 / 21 . . MC simulation Motivation Numerical Calculation . . . . . . . . . Coannihilation scenario 1 (NLSP ˜ t 1 ) The lighter stop ˜ t 1 is the NLSP: m ˜ 1 ≲ m ˜ χ 0 t 1 χ 0 χ 0 χ 0 1 , f f ′ b ˜ χ 0 Possible decay channels: ˜ t 1 → t ˜ 1 , bW ˜ 1 , c ˜ 1 χ 0 1 + m b + m W , assume ˜ For m ˜ 1 + m c < m ˜ t 1 < m ˜ t 1 → c ˜ χ 0 χ 0 1 (100%). LHC signature: monojet + / E T c (soft) p χ 0 ˜ ˜ t 1 1 χ 0 ˜ 1 ˜ t ∗ 1 ¯ c (soft) p q/g
. . . . . . . . . Conclusions Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) Dark matter Coannihilation scenarios 16 / 21 . Numerical Calculation Motivation MC simulation . . . . . . . . . . χ 0 Scenario 1 (NLSP ˜ t 1 ): ˜ t 1 → c ˜ 1 300 ATLAS 4.7 fb -1 , 95% CL CMS 5.0 fb -1 , 95% CL 250 0 + m c 200 mass diff. 20% 0 (GeV) t 1 = m ∼ χ 1 m ∼ 150 χ 1 0 + m W + m b m ∼ t 1 = m ∼ 100 CDF 2.6 fb -1 , 95% CL χ 1 m ∼ 50 LEP 50 100 150 200 250 300 m ∼ t 1 (GeV) Exclude m ˜ t 1 ≲ 220GeV for m ˜ t 1 ≃ m ˜ 1 + m c χ 0 ATLAS � s = 7TeV , 4.7fb − 1 , monojet + / E T [ATLAS-CONF-2012-084] CMS � s = 7TeV , 5.0fb − 1 , monojet + / E T [arXiv:1206.5663]
. . . . . . . . . Conclusions Sep 8, 2012 Dark matter implications at the LHC Zhao-Huan YU (IHEP) Dark matter Coannihilation scenarios 17 / 21 . Motivation . MC simulation Numerical Calculation . . . . . . . . . χ ± Coannihilation scenario 2 (NLSP ˜ 1 ) χ ± The lighter chargino ˜ 1 is the NLSP: m ˜ 1 ≲ m ˜ 1 < m ˜ χ ± χ 0 t 1 Fixing ( m ˜ 1 − m ˜ 1 ) / m ˜ 1 = 10% , for m b + m ˜ 1 < m ˜ t 1 < m ˜ 1 + m t , χ ± χ ± χ 0 χ 0 χ 0 1 → f f ′ ˜ χ ± χ ± χ 0 assume ˜ t 1 → b ˜ 1 (100%) and ˜ 1 (100%). LHC signature: 1-2 b-jets + / E T b f 1 (soft) p f 2 (soft) ˜ t 1 χ + ˜ χ 0 ˜ 1 1 χ 0 ˜ χ − ˜ 1 1 ˜ t ∗ 1 f 3 (soft) p f 4 (soft) ¯ b
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