WIMPs: An Introduction - PDF Free Download

WIMPs: An Introduction Manuel Drees Bonn University & Bethe Center for Theoretical Physics Introduction to WIMPs p. 1/59

Contents 1 The WIMP Miracle Introduction to WIMPs p. 2/59

Contents 1 The WIMP Miracle 2 Have WIMPS been Detected (Directly)? Introduction to WIMPs p. 2/59

Contents 1 The WIMP Miracle 2 Have WIMPS been Detected (Directly)? 3 Asymmetric Dark Matter? Introduction to WIMPs p. 2/59

Contents 1 The WIMP Miracle 2 Have WIMPS been Detected (Directly)? 3 Asymmetric Dark Matter? 4 WIMPs and Colliders Introduction to WIMPs p. 2/59

Contents 1 The WIMP Miracle 2 Have WIMPS been Detected (Directly)? 3 Asymmetric Dark Matter? 4 WIMPs and Colliders 5 Summary Introduction to WIMPs p. 2/59

Conditions for Dark Matter Candidates Requirements for a good DM candidate χ: Must have lifetime τ χ τ U Introduction to WIMPs p. 3/59

Conditions for Dark Matter Candidates Requirements for a good DM candidate χ: Must have lifetime τ χ τ U Must be electrically neutral (otherwise not dark) Introduction to WIMPs p. 3/59

Conditions for Dark Matter Candidates Requirements for a good DM candidate χ: Must have lifetime τ χ τ U Must be electrically neutral (otherwise not dark) Must have correct relic density: Ω χ 0.22 If DM consists of thermally produced elementary particles: Leads to events with missing E T at colliders! Counter examples: axions; dark atoms; primordial black holes; kev neutrinos: not covered in this talk. Note: Proves that LHC does not recreate conditions of the early universe! Introduction to WIMPs p. 3/59

The WIMP Miracle Assume χ was in full thermal equilibrium with SM particles at sufficiently high temperature T : χ production rate n χ σ(χχ SM)v χ > expansion rate H Introduction to WIMPs p. 4/59

The WIMP Miracle Assume χ was in full thermal equilibrium with SM particles at sufficiently high temperature T : χ production rate n χ σ(χχ SM)v χ > expansion rate H n χ e m χ/t, σ(χχ SM)v T 0 or2, H T 2 /M Planck = equality ( freeze-out ) reached at T F m χ /20 Introduction to WIMPs p. 4/59

WIMPs and Early Universe Ω χ h 2 can be changed a lot in non standard cosmologies (involving T T BBN ): Increased: Higher expansion rate H(T T F ); additional non thermal χ production at T < T F ;... Decreased: Reduced expansion rate H(T T F ); entropy production at T < T F ;... Determining σ(χχ SM) allows probe of very early Universe, once χ has been established to be the DM particle! e.g. MD, Iminniyaz, Kakizaki, arxiv:0704.1590 Introduction to WIMPs p. 5/59

High T Production of DM Particles Sometimes χ production from thermalized SM particles is called thermal production even if χ never was in thermal equilibrium: Introduction to WIMPs p. 6/59

High T Production of DM Particles Sometimes χ production from thermalized SM particles is called thermal production even if χ never was in thermal equilibrium: If σ(χχ SM) 1/s: Production maximal at T m χ ( freeze in, Hall et al., arxiv:0911.1120) If σ(χχ SM) s/λ 4 : Produced dominantly at highest possible temperature, T R. Either way, χ interactions with SM particles are too weak to give missing E T signal, unless χ has partners that can be produced via gauge interactions (ex.: gravitino G, axino ã) Introduction to WIMPs p. 6/59

Have WIMPs Been Detected Directly? Direct detection search for elastic WIMP nucleon scattering Introduction to WIMPs p. 7/59

Have WIMPs Been Detected Directly? Direct detection search for elastic WIMP nucleon scattering Kinematics: v χ v Sun 10 3 c Introduction to WIMPs p. 7/59

Have WIMPs Been Detected Directly? Direct detection search for elastic WIMP nucleon scattering Kinematics: v χ v Sun 10 3 c = energy transfer to nculeus A: ( ) Q < min 10 6 m 2 χ m A, 10 6 m A < 100 kev = Cannot excite (most) nuclei! Momentum transfer < 100 MeV = may need to worry about elastic form factors; quite well understood (for spin indep. scattering) Introduction to WIMPs p. 7/59

Recoil Spectrum dr dq F(Q) 2 v max v min dv v f 1 (v) Introduction to WIMPs p. 8/59

Recoil Spectrum dr dq F(Q) 2 v max v min dv v f 1 (v) f 1 (v) : WIMP velocity distribution. Usually assumed Maxwellian in rest frame of the galaxy, cut off at v esc = v max. Gives roughly exponentially falling spectrum. Introduction to WIMPs p. 8/59

Normalized Recoil Spectra 1/R dr/dq [1/keV] 1 0.1 0.01 0.001 m χ =100 GeV, A=73 m χ =100 GeV, A=136 m χ =10 GeV, A=73 m χ =10 GeV, A=16 0.0001 0 20 40 60 80 100 Q [kev] Introduction to WIMPs p. 9/59

Experimental Challenges Spectrum backed up against instrumental threshold Q min Introduction to WIMPs p. 10/59

Experimental Challenges Spectrum backed up against instrumental threshold Q min Rates of current interest background rate, e.g. from radioactive decay (for most materials) = try to discriminate between nuclear recoil (signal) and e/γ induced events (background)! Introduction to WIMPs p. 10/59

DAMA Pure scintillation detectors (doped NaI) in Gran Sasso: 6 years with 100 kg (DAMA) 6 years with 250 kg (DAMA/LIBRA) Introduction to WIMPs p. 11/59

DAMA Pure scintillation detectors (doped NaI) in Gran Sasso: 6 years with 100 kg (DAMA) 6 years with 250 kg (DAMA/LIBRA) All events are counted. Introduction to WIMPs p. 11/59

DAMA Pure scintillation detectors (doped NaI) in Gran Sasso: 6 years with 100 kg (DAMA) 6 years with 250 kg (DAMA/LIBRA) All events are counted. Observe few percent modulation of total rate Introduction to WIMPs p. 11/59

DAMA Results 2-6 kev Residuals (cpd/kg/kev) DAMA/NaI (0.29 ton yr) (target mass = 87.3 kg) DAMA/LIBRA (0.53 ton yr) (target mass = 232.8 kg) 2-6 kev Time (day) Residuals (cpd/kg/kev) DAMA/LIBRA 250 kg (0.87 ton yr) Time (day) Introduction to WIMPs p. 12/59

DAMA: Problems No e/γ discrimination is attempted, although some (statistical) discrimination should be possible using light curve Introduction to WIMPs p. 13/59

DAMA: Problems No e/γ discrimination is attempted, although some (statistical) discrimination should be possible using light curve Deduced shape of spectrum weird: Falls towards small Q! (Depends on 3 dimensional WIMP velocity distribution.) Amplitude of modulation is getting smaller! E.g. in 2 6 kev ee bin (in units of 10 3 /kg day kev ee ): DAMA 1995 2001: 20.0 ± 3.2 LIBRA 2003 2007: 10.7 ± 1.9 LIBRA 2007 2009: 8.5 ± 2.2 Ratio LIBRAII DAMA = 0.43 ± 0.13 More than 4σ away from 1! Results for 2 4, 2 5 kev ee bins similar. Introduction to WIMPs p. 13/59

CoGeNT: Time Averaged Analysis Operate cryogenic Ge detectors with very low threshold Q min. Introduction to WIMPs p. 14/59

CoGeNT: Time Averaged Analysis Operate cryogenic Ge detectors with very low threshold Q min. Originally: Found excess relative to simple bckgd model at very low Q = small m χ ; Introduction to WIMPs p. 14/59

CoGeNT: Time Averaged Analysis Operate cryogenic Ge detectors with very low threshold Q min. Originally: Found excess relative to simple bckgd model at very low Q = small m χ ; χ 2 fit with signal not significantly better than with pure background: no claim of signal in published paper! Introduction to WIMPs p. 14/59

CoGeNT: Results Introduction to WIMPs p. 15/59

CoGeNT: Modulation After 15 months of data taken: Find 2.8σ evidence for annual modulation Introduction to WIMPs p. 16/59

CoGeNT: Modulation After 15 months of data taken: Find 2.8σ evidence for annual modulation Much too large to be compatible with time averaged signal, for standard halo Introduction to WIMPs p. 16/59

CoGeNT: Modulation After 15 months of data taken: Find 2.8σ evidence for annual modulation Much too large to be compatible with time averaged signal, for standard halo No event by event e/γ rejection at these low energies Introduction to WIMPs p. 16/59

CoGeNT: Summary No signal claimed in time averaged analysis! Introduction to WIMPs p. 17/59

CoGeNT: Summary No signal claimed in time averaged analysis! There is a large, poorly understood background Introduction to WIMPs p. 17/59

CoGeNT: Summary No signal claimed in time averaged analysis! There is a large, poorly understood background Modulation signal statistically very weak, and way too large Introduction to WIMPs p. 17/59

CRESST Uses cryogenic CaWO 4 crystals; detect scintillation light and heat: Allows event by event discrimination! See 67 events after cuts. Introduction to WIMPs p. 18/59

CRESST Uses cryogenic CaWO 4 crystals; detect scintillation light and heat: Allows event by event discrimination! See 67 events after cuts. Unfortunately, quite large backgrounds (rough estimates, not final fit): e/γ events: 8 α background: 9.2 n background: 1.5 to 11.4 Pb recoil (from 210 Po decay): 17 Much of fitted excess has essentially no light: only half a signal Introduction to WIMPs p. 18/59

CRESST: Results Introduction to WIMPs p. 19/59

CRESST: Results What is negative light yield? Introduction to WIMPs p. 19/59

CRESST: Correlation events in signal region (α subtracted) 20 15 10 5 0 y = 0.44x + 2.1 (χ 2 = 7.3 / 6 d.o.f.) Data y = 7.2 (χ 2 = 11.4 / 7 d.o.f.) 5 10 15 20 events in α reference region Introduction to WIMPs p. 20/59

Exclusion Limits from Other Expts Best limit for larger masses from Xenon100. Uses ionization and scintillation. Very few events after cuts. Alas, not safe for m χ 12 GeV: bound strongly depends on high v tail of f 1 (v), and on experimental energy resolution. Xenon10 more robust at small Q; excludes DAMA, CRESST, original CoGeNT signal for usual WIMP CDMS (+ EDELWEISS) second best for not too small m χ. Uses phonons and ionization. Very few events after cuts. Not safe below 12 GeV. Introduction to WIMPs p. 21/59

Theory of WIMP Nucleus Scattering L eff = c N NN χχ + an Nγµ N χγ µ χ + b N Nγµ γ 5 N χγ µ γ 5 χ For scalar χ: γ µ i µ in 2 nd term; 3 rd term absent For Majorana χ: 2 nd term absent 1 st, 2 nd term give spin independent (s.i.) interaction, 3 rd term gives spin dependent (s.d.) interaction. Usual WIMP : same s.i. scattering on p and n! Introduction to WIMPs p. 22/59

Isospin violation in s.i. interaction? σ s.i. χp σ s.i. χn true for Higgs exchange (in particular, in (N)MSSM): massive quarks are same for p, n! Introduction to WIMPs p. 23/59

Isospin violation in s.i. interaction? σ s.i. χp σ s.i. χn true for Higgs exchange (in particular, in (N)MSSM): massive quarks are same for p, n! Not true for q, q (1) exchange: quark charges matter! But: M(χq χq) has same sign for all quarks: no cancellations = isospin violation in praxis not important, since all nuclei have similar n/p ratio. Introduction to WIMPs p. 23/59

Large isospin violation in s.i. interaction? M(χA χa) 2 Za p + (A Z)a n 2 = need a p a n < 0 for significant isospin violation: arrange for cancellation in unwanted nuclei (e.g. Xe). Introduction to WIMPs p. 24/59

Large isospin violation in s.i. interaction? M(χA χa) 2 Za p + (A Z)a n 2 = need a p a n < 0 for significant isospin violation: arrange for cancellation in unwanted nuclei (e.g. Xe). Does not work for CDMS vs. CoGeNT: same target! Increases required a p even more, to describe claimed signals = Need new light gauge bosons! Introduction to WIMPs p. 24/59

Weisskopf s (?) Theorem A theory that explains all data must be wrong, since at any given point some data are wrong. Introduction to WIMPs p. 25/59

Weisskopf s (?) Theorem A theory that explains all data must be wrong, since at any given point some data are wrong. Competition between null experiments with few (background) events after cuts, and claimed signals with large, not always well understood backgrounds! Introduction to WIMPs p. 25/59

Asymmetric Dark Matter? Cosmology: Ω DM 5Ω baryon : strange coincidence? Introduction to WIMPs p. 26/59

Asymmetric Dark Matter? Cosmology: Ω DM 5Ω baryon : strange coincidence? Ω baryon determined by baryon antibaryon asymmetry, not by thermal decoupling of baryons: try same thing for WIMPs? Most attractive: χ χ asymmetry related to baryon asymmetry [O(50) papers] = number density n χ n p after annihilating away symmetric component Introduction to WIMPs p. 26/59

Explaining Ω DM /Ω baryon Follows if m χ 5m p! Introduction to WIMPs p. 27/59

Explaining Ω DM /Ω baryon Follows if m χ 5m p! Alas: m χ has no known relation to m p. m χ 5m p just as mysterious as Ω DM 5Ω baryon = Haven t explained anything! Introduction to WIMPs p. 27/59

Explaining Ω DM /Ω baryon Follows if m χ 5m p! Alas: m χ has no known relation to m p. m χ 5m p just as mysterious as Ω DM 5Ω baryon = Haven t explained anything! Circular logic: ADM with m χ 5 GeV interesting because there are signals for low mass WIMPs; low mass WIMPs interesting because ADM explains Ω DM /Ω baryon?? Introduction to WIMPs p. 27/59

WIMPs and Colliders 1 Generalities: WIMP DM Production and Missing E T Introduction to WIMPs p. 28/59

WIMPs and Colliders 1 Generalities: WIMP DM Production and Missing E T 2 Light Gauge Bosons Introduction to WIMPs p. 28/59

WIMPs and Colliders 1 Generalities: WIMP DM Production and Missing E T 2 Light Gauge Bosons 3 SUSY DM and the LHC Inverse Problem Introduction to WIMPs p. 28/59

WIMPs and Colliders 1 Generalities: WIMP DM Production and Missing E T 2 Light Gauge Bosons 3 SUSY DM and the LHC Inverse Problem 4 Higgs Searches and Direct DM Detection Introduction to WIMPs p. 28/59

Cannot predict missing E T from χχ production Thermal WIMP: Only know total χχ SM cross section; contribution of specific final states (e + e, uū + d d) not known Introduction to WIMPs p. 29/59

Cannot predict missing E T from χχ production Thermal WIMP: Only know total χχ SM cross section; contribution of specific final states (e + e, uū + d d) not known Ω χ h 2 determined from σ(χχ SM) near threshold (T F m χ /20 = s 4m 2 χ). At colliders need 3 body final state to get signature (e.g. e + e χχγ, q q χχg) = typically need σ(χχ SM) at s 6 to 10m 2 χ! Introduction to WIMPs p. 29/59

Model-independent approach Goodman et al., arxiv:1005.1286 and 1008.1783; Bai, Fox, Harnik, arxiv:1005.3797; Wang, Li, Shao, Zhang, arxiv:1107.2048; Fox, Harnek, Kopp, Tsai, arxiv:1103.0240 Parameterize χ interaction with relevant SM fermion through dim 6 operator; e.g. for hadron colliders: L eff = G χ χγ χ χ qγ q q χ Majorana = Γ χ {1,γ 5,γ µ γ 5 } Γ q {1,γ 5,γ µ,γ µ γ 5 } If Γ χ, Γ q {1,γ 5 } : G χ = m q /(2M 3 ) (chirality violating!), else Γ χ = 1/(2M 2 ) Rajamaran, Shepherd, Tait, Wijango, arxiv:1108.1196. Introduction to WIMPs p. 30/59

Γ χ = γ µ γ 5 (corr. to spin-dep. interact.) Introduction to WIMPs p. 31/59

Γ χ = 1 (corr. to spin-indep. interact.) Introduction to WIMPs p. 32/59

Remarks For Γ χ = 1 (spin-indep. interact.): Current bound poor; ultimate LHC reach interesting only for m χ 5 GeV. Introduction to WIMPs p. 33/59

Remarks For Γ χ = 1 (spin-indep. interact.): Current bound poor; ultimate LHC reach interesting only for m χ 5 GeV. For Γ χ = γ µ γ 5 (spin-dep. interact.): LHC bound better than (comparable to) direct search limit for m χ ( ) 20 GeV; future reach factor 10 3 better, if no other BSM source of missing E T exists. Γ χ = γ 5 similar to first case; cannot be probed in direct WIMP detection (rate v 2 χ) Introduction to WIMPs p. 33/59

2 DM and Light (Gauge) Bosons (At least) 3 kinds of WIMP models require light (m few GeV) (gauge) bosons U: MeV DM: Suggested as explanation of 511 kev line (= slow e + ) excess from central region of our galaxy (Boehm et al., astro-ph/0309686). Should have m χ 10 MeV (γ constraints) = m χ m U 200 MeV to mediate χχ e + e ; fixes g Uχχ g Ue+ e /m2 U! (Unless 2m χ m U.) PAMELA/FermiLAT inspired TeV DM: Needs light boson for Sommerfeld enhancement (e.g. Arkani-Hamed et al., arxiv:0810.0713(4)) (χχ U U 4l is also somewhat less constrained by γ spectrum than χχ 2l.) Introduction to WIMPs p. 34/59

DAMA/CoGeNT inspired few GeV DM: Needs light mediator to achieve sufficiently large σ χp. (2 different mediators for isospin violation to evade bounds: Cline, Frey, arxiv:1108.1391) Introduction to WIMPs p. 35/59

Light Gauge Bosons (cont d) In all cases: U couplings to (most) SM particles must be 1 to evade bounds! (g µ 2, meson decays, ν cross sections, APV,... ). Introduction to WIMPs p. 36/59

Light Gauge Bosons (cont d) In all cases: U couplings to (most) SM particles must be 1 to evade bounds! (g µ 2, meson decays, ν cross sections, APV,... ). Possible explanation: kinetic mixing with γ/b boson! Is 1-loop effect = squared Uf f coupling is O(α 3 ). Introduction to WIMPs p. 36/59

Signatures of light gauge bosons If m U > 2m χ : U χχ dominant! Is invisible = need extra tag, e.g. e + e γu γ+ nothing. Introduction to WIMPs p. 37/59

Signatures of light gauge bosons If m U > 2m χ : U χχ dominant! Is invisible = need extra tag, e.g. e + e γu γ+ nothing. Physics background s = lower energy is better! Borodatchenkova, Choudhury, MD, hep-ph/0510147 Introduction to WIMPs p. 37/59

Sensitivity at B factories (100 fb 1) 1 0.01 m χ > M U /2 max. sensitivity (e + e - channel) g χ g er 0.0001 upper bound from g e -2 max. sensitivity (invisible channel) 1e-06 1e-08 m χ < M U /2 0.001 0.01 0.1 M U [GeV] Red, black: Regions allowed by Ω χ, σ(χχ e + e ). Introduction to WIMPs p. 38/59

Signatures of light gauge bosons (cont.d) If m U < 2m χ : U l + l Introduction to WIMPs p. 39/59

Signatures of light gauge bosons (cont.d) If m U < 2m χ : U l + l Sufficiently light U can even be produced in fixed target experiments: e N e e + e N (tridents), with peak in M e+ e Introduction to WIMPs p. 39/59

Signatures of light gauge bosons (cont.d) If m U < 2m χ : U l + l Sufficiently light U can even be produced in fixed target experiments: e N e e + e N (tridents), with peak in M e+ e First exptl. results from MAMI A1 arxiv:1101.4091 and JLAB APEX arxiv:1108.2750 Excludes new mass ranges around 200 to 300 MeV for A U kinetically mixed with photon. Introduction to WIMPs p. 39/59

A1 and APEX results Introduction to WIMPs p. 40/59

SUSY DM and LHC Inverse Problem Saw above: WIMP searches at colliders not promising, if WIMP is only accessible new particle. Fortunately, in many cases the WIMP is the lightest of many new particles! True in SUSY. (Also in Little Higgs.) Recall: Primary motivation for SUSY not related to DM! Stabilizes hierarchy m 2 Higgs M2 Planck Allows unification of gauge couplings Introduction to WIMPs p. 41/59

Features of SUSY Need superpartner for each SM particle: Same rep. of gauge group, spin differs by 1/2 Introduction to WIMPs p. 42/59

Features of SUSY Need superpartner for each SM particle: Same rep. of gauge group, spin differs by 1/2 Need at least 2 Higgs doublets (anomalies, m t m b 0) Introduction to WIMPs p. 42/59

Features of SUSY Need superpartner for each SM particle: Same rep. of gauge group, spin differs by 1/2 Need at least 2 Higgs doublets (anomalies, m t m b 0) SUSY implies equal masses for partners = SUSY must be broken Naturalness: sparticle masses should be at weak scale (strictly true only for 3rd generation, elw gauginos) Introduction to WIMPs p. 42/59

SUSY DM candidate: sneutrino ν Disfavored theoretically: not LSP in constrained models Introduction to WIMPs p. 43/59

SUSY DM candidate: sneutrino ν Disfavored theoretically: not LSP in constrained models Excluded experimentally by direct searches Introduction to WIMPs p. 43/59

SUSY DM candidate: sneutrino ν Disfavored theoretically: not LSP in constrained models Excluded experimentally by direct searches ν R can be candidate in extended theories, e.g. with gauged U(1) B L at TeV scale Introduction to WIMPs p. 43/59

SUSY DM candidate: neutralino χ 0 1 Mixture of B, W 3, h 0 u, h 0 d Introduction to WIMPs p. 44/59

SUSY DM candidate: neutralino χ 0 1 Mixture of B, W 3, h 0 u, h 0 d In constrained models: often is lightest sparticle in visible sector! (Other possibility: lightest stau τ 1 ) Introduction to WIMPs p. 44/59

SUSY DM candidate: neutralino χ 0 1 Mixture of B, W 3, h 0 u, h 0 d In constrained models: often is lightest sparticle in visible sector! (Other possibility: lightest stau τ 1 ) In most of parameter space: χ 0 1 B, and predicted Ω χ 0 1 h 2 too large! O(1 to 10) rather than O(0.1) in standard cosmology, Introduction to WIMPs p. 44/59

Regions with correct Ω χ 0 1 h 2 Co annihilation region: m χ 0 1 m τ1 Introduction to WIMPs p. 45/59

Regions with correct Ω χ 0 1 h 2 Co annihilation region: m χ 0 1 m τ1 Higgs funnel(s): m χ 0 1 m h /2, m A /2 Introduction to WIMPs p. 45/59

Regions with correct Ω χ 0 1 h 2 Co annihilation region: m χ 0 1 m τ1 Higgs funnel(s): m χ 0 1 m h /2, m A /2 Well tempered neutralino: µ M 1 M Z = χ 0 1 is B h 0 mixture. (Requires m q m g in cmssm; can be arranged anywhere in NUHM.) Introduction to WIMPs p. 45/59

Impact of LHC searches Is model dependent: Only probe g, q sector so far! Here: Assume cmssm for defineteness. Introduction to WIMPs p. 46/59

Impact of LHC searches Is model dependent: Only probe g, q sector so far! Here: Assume cmssm for defineteness. Well tempered neutralino, A pole need large m q : limits still fairly weak: m g,min increased from 400 GeV to 550 GeV Introduction to WIMPs p. 46/59

Impact of Indirect DM Searches No halo signal in co annihilation region; ν from Sun small Introduction to WIMPs p. 47/59

Impact of Indirect DM Searches No halo signal in co annihilation region; ν from Sun small Signals very small in A funnel Introduction to WIMPs p. 47/59

Impact of Indirect DM Searches No halo signal in co annihilation region; ν from Sun small Signals very small in A funnel Well-tempered neutralino most promising, especially ν from Sun, but present limits not constraining Introduction to WIMPs p. 47/59

Impact of direct WIMP Searches XENON, CDMS EDELWEISS begin to probe well tempered neutralino Introduction to WIMPs p. 48/59

Impact of direct WIMP Searches XENON, CDMS EDELWEISS begin to probe well tempered neutralino Signals in other regions very small Introduction to WIMPs p. 48/59

Impact of Future WIMP Discovery at Collider Generically: could determine: WIMP mass: Very useful for indirect searches (greatly reduced look elsewhere problem); less so for direct searches, once m χ m N WIMP couplings: Determine cross sections and final states in indirect searches; determine cross sections in direct searches Introduction to WIMPs p. 49/59

Fitting SUSY parameters at LHC ( inverse problem ) Feasibility (resulting errors) very strongly depend on where we are in parameter space! Introduction to WIMPs p. 50/59

Fitting SUSY parameters at LHC ( inverse problem ) Feasibility (resulting errors) very strongly depend on where we are in parameter space! Good: Low sparticle masses, many leptons e,µ in final states. Not so good: Large masses, mostly hadronic final states. Introduction to WIMPs p. 50/59

Case study: τ 1 co annihilation region in cmssm Needs m τ1 m χ 0 1 15 GeV Arnowitt et al., arxiv:0802.2968 = χ 0 2 τ 1τ, χ ± 1 τ ± 1 ν τ have nearly unit branching ratio = no di lepton edges! Introduction to WIMPs p. 51/59

Case study: τ 1 co annihilation region in cmssm Needs m τ1 m χ 0 1 15 GeV Arnowitt et al., arxiv:0802.2968 = χ 0 2 τ 1τ, χ ± 1 τ ± 1 ν τ have nearly unit branching ratio = no di lepton edges! τ 1 χ 0 1τ gives rather soft τ: Difficult to detect! Study three classes of final states: (i) 2τ + 2j + E/ T (ii)4 non b j + E/ T (iii) leading b + 3j + E/ T Introduction to WIMPs p. 51/59

Result of fit 0.12 Ω ~ h 2 χ 0 1 0.11 0.1 0.09 0.08 8 9 10 11 12 13 M (GeV) Introduction to WIMPs p. 52/59

Result of fit 0.12 Ω ~ h 2 χ 0 1 0.11 0.1 0.09 0.08 8 9 10 11 12 13 M (GeV) Unfortunately, chosen benchmark point (m g = 830 GeV, m q 750 GeV) is most likely excluded! Introduction to WIMPs p. 52/59

Scan of Parameter Space Arkani-Hamed et al., hep-ph/0512190 15 parameter description of weak scale MSSM Introduction to WIMPs p. 53/59

Scan of Parameter Space Arkani-Hamed et al., hep-ph/0512190 15 parameter description of weak scale MSSM Fix m A = 850 GeV, A 3 = 800 GeV Introduction to WIMPs p. 53/59

Scan of Parameter Space Arkani-Hamed et al., hep-ph/0512190 15 parameter description of weak scale MSSM Fix m A = 850 GeV, A 3 = 800 GeV Randomly choose m q, g [600, 1000] GeV, other masses [100, 1000] GeV, tan β [2, 50] Consider 1808 observables, both counting rates and binned distributions Introduce χ 2 like variable ( S AB ) 2 = 1 n sig n sig i=1 ( s A i s B i σ AB i ) 2 Only significant signatures included Introduction to WIMPs p. 53/59

Results and Remarks Found 283 degenerate pairs, with (δs AB ) 2 < 0.285, for 43,026 models (i.e., sets of parameters) Introduction to WIMPs p. 54/59

Results and Remarks Found 283 degenerate pairs, with (δs AB ) 2 < 0.285, for 43,026 models (i.e., sets of parameters) Note Their observables are correlated = (δs AB ) 2 is no true χ 2 = need MC to intepret it, from comparing runs with different random no. seed: is this reliable estimator for comparing different parameter sets? Introduction to WIMPs p. 54/59

Simpler approach Bornhauser and MD, in progress Define 12 disjunct event classes, depending on no., charge, flavor of leptons Introduction to WIMPs p. 55/59

Simpler approach Bornhauser and MD, in progress Define 12 disjunct event classes, depending on no., charge, flavor of leptons Consider 7 mostly uncorrelated observables for each class: No. of events; n τ ± ; n b ; n j ; n 2 j ; H T Introduction to WIMPs p. 55/59

Results of simpler approach W/o syst. error: only one of 283 degenerate pairs has p > 0.05, and two parameter sets really are very similar! (Except for heavy sleptons.) Introduction to WIMPs p. 56/59

Results of simpler approach W/o syst. error: only one of 283 degenerate pairs has p > 0.05, and two parameter sets really are very similar! (Except for heavy sleptons.) Introducing syst. errors as Arkani-Hamed et al.: 41 out of 283 pairs have p > 0.05; still are pretty similar physically Introduction to WIMPs p. 56/59

4 Impact of Higgs Searches In many WIMP models, Higgs exch. dominates χp scattering, in which case σ χp 1/m 4 H : crucial to know Higgs mass! Introduction to WIMPs p. 57/59

4 Impact of Higgs Searches In many WIMP models, Higgs exch. dominates χp scattering, in which case σ χp 1/m 4 H : crucial to know Higgs mass! In SUSY at large tan β: 0 σ χ 1 p tan 2 β/m 4 A : need info on heavy Higgses! TeVatron and CMS searches for H,A τ + τ significantly increase lower bound on DM allowed m χ 0 1 in general MSSM (Aborno Vasquez, Belanger, Boehm, arxiv:1108.1338); exclude scenarios with very large σ χ 0 1 p. Introduction to WIMPs p. 57/59