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SUSY Dark Matter and ATLAS

SUSY Dark Matter and ATLAS. Dan Tovey University of Sheffield. SUSY Dark Matter and ATLAS. By 2013 concept of TeV scale SUSY as a solution to the gauge hierarchy problem will have been strongly tested by ATLAS.

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SUSY Dark Matter and ATLAS

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  1. SUSY Dark Matter and ATLAS Dan Tovey University of Sheffield 1

  2. SUSY Dark Matter and ATLAS • By 2013 concept of TeV scale SUSY as a solution to the gauge hierarchy problem will have been strongly tested by ATLAS. • Will hopefully lead to discovery and subsequent measurements of properties of supersymmetric particles. • TeV scale SUSY also provides solution to the Dark Matter problem of astrophysics however. • By 2013 there will be a wealth of data from next generation tonne-scale direct search Dark Matter experiments. • What can ATLAS say about Dark Matter, and what can Dark Matter experiments say about SUSY? 2

  3. WIMP Dark Matter • Astrophysics • Stellar/galactic dynamics g >90% of matter invisible • g ‘dark’ matter. • Cosmological measurements g matter densityWM~0.3. • Nucleosynthesisgbaryon < 0.05 • gmajority of dark matter non-baryonic. • Particle Physics • R-Parity conserving SUSY • g solves gauge hierarchy problem etc …. • g LSP stable relic from Big Bang • gWIMP dark matter? • Confirmation would be major triumph for Particle Physics and Cosmology. 3

  4. Galactic Rotation Curves 150 NGC 6503 observations halo 100 Velocity (km/s) 50 disk gas 0 0 10 20 30 Radius (kpc) • Scale 10kPc (30 000 light years). • Uses Doppler shift of light from star in spiral galaxy to give velocity (red shift). • Expect velocity to fall off with distance from centre • ...but it doesn’t. • Halo out to 200kPc. R 4

  5. Gravitational Lensing Can use gravitational lensing to map matter distributions in clusters. Image Distant Galaxy Image Foreground Cluster Observer 5

  6. Lensing Map • Distribution of visible matter + dark matter in CL0024+1654 mapped in this way. J.A. Tyson et al., Ap. J. 498 (1998) L107. 6

  7. WIMP Interactions ~ ~ ~ c01 c01 c01 ~ c01 Z0,h,H q q • WIMPs predicted to interact with nuclei via elastic scattering. g e.g. neutralino (SUSY) WIMPs: ~ q q q 7

  8. dR =p.Af(A) .S(A,ER).I(A).F2(A,ER).g(A).e(Ev) dEv Searching for WIMPs • Predicted nuclear recoil energy spectrum depends on astrophysics (DM halo model), nuclear physics (form-factors, coupling enhancements) and particle physics (WIMP mass and coupling). p = WIMP-nucleon scattering cross-section, f(A) = mass fraction of element A in target, S(A,ER) ~ exp(-ER/E0r) for recoil energy ER, I(A) = spin/coherence enhancement (model-dep.), F2(A,ER) = nuclear form-factor, g(A) = quenching factor (Ev/ER), (Ev)= event identification efficiency. 8

  9. Nuclear Recoil Spectra To first order shape of predicted spectrum independent of WIMP model (e.g. MSSM). 9

  10. Direct DM Searches EDELWEISS CDMS DAMA ZEPLIN-I CRESST-II ZEPLIN-2 EDELWEISS 2 ZEPLIN-4 GENIUS XENON ZEPLIN-MAX • Next generation of tonne-scale direct Dark Matter detection experiments should give sensitivity to scalar WIMP-nucleon cross-sections ~ 10-10 pb. 10

  11. What can LHC Tell Us About DM? SUSY studies at the LHC will proceed in four general stages: • SUSY Discovery phase (inclusive searches) • success assumed! • Inclusive Studies (comparison of significance in inclusive channels etc). • Relevance to DM: First rough predictions of Wch2 within specific model framework (e.g. Constrained MSSM / mSUGRA). • Exclusive studies (calculation of model-independent SUSY masses) and interpretation within specific model framework. • Relevance to DM: Model-independent calculation of LSP mass for comparison with e.g. direct searches; detailed model-dependent calculations of DM quantities (Wch2, scp, fsun etc.) • Less model-dependent interpretation. • Relevance to DM: Approach to model-independent measurement of Wch2 etc. through measurement of all relevant masses etc. 11

  12. Stage 1: Inclusive Searches • Tonne scale direct search dark matter detectors sensitive to spin-independent WIMP-nucleon cross-sections ~ 10-10 pb. • Complementary reach to LHC experiments within CMSSM parameter space, particularly for high values of tan(b). ATLAS 12

  13. Stage 2: Inclusive Studies LHC Point 5 (Physics TDR) • Following any discovery of SUSY next task will be to test broad features of potential Dark Matter candidate. • Question1: Is R-Parity Conserved? • If YES possible DM candidate • LHC experiments sensitive only to LSP lifetimes < 1 ms (<< tU ~ 13.7 Gyr) R-Parity Conserved R-Parity Violated ATLAS ~ Non-pointing photons from c01gGg ~ ~ • Question 2: Is the LSP the lightest neutralino? • Natural in many MSSM models • If YES then test for consistency with astrophysics • If NO then what is it? • e.g. Light Gravitino DM from GMSB models (not considered here) GMSB Point 1b (Physics TDR) ATLAS 13

  14. Stage 2/3: Model-Dependent DM CMSSM A0=0 , Ellis et al. hep-ph/0303043 Disfavoured by BR (b  s) = (3.2  0.5)  10-4 (CLEO, BELLE) Favoured by g-2 (E821) Assuming  = (26  10)  10 -10 from SUSY ( 2  band) 0.094    h2  0.129 (WMAP) Forbidden (LSP = stau) • If a viable DM candidate is found initially assume specific consistent model • e.g. CMSSM / mSUGRA. • Measure model parameters (m0, m1/2, tan(b), sign(m), A0 in CMSSM): Stage 2/3. • Check consistency with accelerator constraints (mh, gm-2, bgsg etc.) • Estimate Wch2g consistency check with astrophysics (WMAP etc.) • Ultimate test of DM at LHC only possible in conjunction with astroparticle experiments g measure mc , scp, fsunetc. 14

  15. Stage 2/3: Model Parameters Point m0 m1/2 A0 tan(b) sign(m) LHC Point 5 100 300 300 2 +1 SPS1a 100 250 -100 10 +1 LHC Point 5 (A0 =300 GeV, tan(b)=2, m>0) Sparticle Mass (LHC Point 5)Mass (SPS1a) qL~690 GeV ~530 GeV 02233 GeV 177 GeV lR157 GeV 143 GeV 01122 GeV 96 GeV Point SPS1a (A0 =-100 GeV, tan(b)=10, m>0) ~ ~ ~ ~ ATLAS • First indication (Stage 2) of CMSSM parameters from inclusive channels • Compare significance in jets + ETmiss + n leptons channels • Detailed measurements (Stage 3) from exclusive channels when accessible. • Consider here two specific example points studied previously: 15

  16. Stage 3: Mass Measurements e+e- + m+m- 30 fb-1 Parameter Expected precision 30 fb-1 300 fb-1 m0 3.2% 1.4% m1/2 0.9%  0.6% tan(b)  0.5%  0.5% Point 5 ATLAS TDR Point m0 m1/2 A0 tan(b) sign(m) LHC Point 5 100 300 300 2 +1 SPS1a 100 250 -100 10 +1 bbq edge llq threshold lq edge llq edge 1% error (100 fb-1) 2% error (100 fb-1) 1% error (100 fb-1) 1% error (100 fb-1) p p TDR, Point 5 ~ c01 TDR, Point 5 ~ ~ ~ ~ q c02 g lR TDR, Point 5 TDR, Point 5 ATLAS ATLAS ATLAS ATLAS q q l l • Model parameters estimated using fit to measured positions of kinematic end-points observed in SUSY events. • Can also give model independent estimate of masses. 16

  17. Stage 3: Relic Density Baer et al. hep-ph/0305191 LHC Point 5: >5s error (300 fb-1) • Use parameter measurements to estimate Wch2 , direct detection cross-section etc. (e.g. for 300 fb-1, SPS1a) • Wch2 = 0.1921  0.0053 • log10(scp/pb) = -8.17  0.04 SPS1a: >5s error (300 fb-1) scp=10-11 pb Micromegas 1.1 (Belanger et al.) + ISASUGRA 7.69 DarkSUSY 3.14.02 (Gondolo et al.) + ISASUGRA 7.69 scp=10-10 pb Wch2 scp scp=10-9 pb 300 fb-1 300 fb-1 No REWSB LEP 2 ATLAS ATLAS Preliminary Preliminary 17

  18. Stage 4: Relic Density Scenarios Slepton Co-annihilation region (LSP ~ pure Bino): need m(c01), m(t1). Small mass difference makes measurement difficult however. 'Focus point' region (significant h component to LSP ): v. difficult, need m(c01), m, mA tan(b) etc. + m(t) to high precision. More study needed ~ ~ ~ ~ ~ c01 t ~ c01 l ~ t1 ~ ~ t1 g/Z/h lR ~ c01 l 'Bulk' region (t-channel slepton exchange - LSP mostly Bino): need m(c01), m(lR), m(t1). 'Bread and Butter' region for LHC Expts. Also 'rapid annihilation funnel' at Higgs pole at high tan(b): m(c01), mA, m, tan(b), m(t) etc. needed. ~ ~ ~ ~ CMSSM A0=0 , Ellis et al. hep-ph/0303043 Representative MSSM scenarios present within e.g. CMSSM 18

  19. Summary • Searches for Dark Matter at non-accelerator experiments in many ways complementary to searches for SUSY at colliders. • Search reach in e.g. CMSSM parameter space complementary. • Dark Matter signals observed at non-accelerator experiments can be confirmed as SUSY through comparison of cross-sections, masses, fluxes etc. with LHC/ATLAS predictions. • SUSY signals observed at ATLAS can be confirmed as Dark Matter only with input (observations) from Dark Matter searches. • Ultimate goal: observation of SUSY neutralinos at ATLAS together with observation of e.g. signal in direct detection Dark Matter experiment at calculated mass and cross-section. • This would be major triumph for both • Particle Physics and Cosmology! 19

  20. Form-Factors • Nuclear form-factors determined from theory • (e.g. Ressell et al. Phys. Rev. C 56 No.1 (1997) 535). 20

  21. Sensitivity Curves Spin-Independent Interactions WIMP-nucleon Cross-Section (pb) WIMP Mass (GeV) • Using energy spectrum formula, detector sensitivity to WIMP mass and interaction cross-section can be calculated. Form of curve approx. L = A.x.exp(B(1+1/x)2), where x = Mw/MT , and A, B are constants. 21

  22. Stage 1: Inclusive Searches • Map 5s discovery reach of e.g. CMS detector in CMSSM m0-m1/2 parameter space. • Uses 'golden' Jets + n leptons + ETmiss discovery channel: • Heavy strongly interacting sparticles produced in initial interaction • Cascade decay via jets and leptons • R-Parity conservation gives stable LSP (neutralino) at end of chain g ETmiss • Sensitivity to models with squark / gluino masses ~ 2.5 - 3 TeV after 1 year of high luminosity running. 22

  23. What Can DM Tell Us About SUSY? Baer et al. hep-ph/0305191 • Direct Dark Matter searches can cover cosmologically favoured (e.g by WMAP) regions of SUSY (e.g. CMSSM) parameter space inaccessible to LHC: • Focus point scenarios (large m0) • Models with large tan(b). ZEPLIN-MAX ZEPLIN-MAX 23

  24. Stage 3: DM Search Comparison Baer et al. hep-ph/0305191 LHC Point 5: >5s error (300 fb-1) SPS1a: >5s error (300 fb-1) scp=10-11 pb scp=10-10 pb scp=10-9 pb No REWSB LEP 2 • Also use model parameters to predict signals observed in terrestrial dark matter searches (SPS1a 300 fb-1) • Direct detection (assumed m>0) log10(scp/pb) = (-8.17  0.04) • Neutrino flux from sun (m>0) log10(fsun/km-2 yr-1) = (10.97  0.03) DarkSUSY 3.14.02 (Gondolo et al.) + ISASUGRA 7.69 ATLAS ATLAS 300 fb-1 300 fb-1 scp fsun Preliminary Preliminary 24

  25. Stage 4: DM Search Comparison ~ ~ • Scalar elastic neutralino-nucleon scattering (DM direct detection) dominated by Higgs and squark exchange gscp function of squark mass, M(c01), mA,tan(b) and m (c01 composition). • Self-annihilation to e.g. neutrinos (indirect detection) proceeds by exchange of Z0, A, charginos/neutralinos or stop/sbottom g need m(c01), mA, m, M2, tan(b), stop/sbottom mass (some overlap). Scalar (spin independent) couplings (tree-level) Jungman, Kamionkowski and Griest, Phys. Rep 267:195-373 (1996) ~ 25

  26. Stage 4: Other Inputs H/Agtt mA = 300 GeV Physics TDR ATLAS • Further input regarding the weak scale SUSY parameters needed. • mA measured from direct search (although difficult for mA > 600 GeV). ATLAS • Higgsino mass parameter m (governs higgsino content of c01) measurable from heavy neutralino edges. • tan(b) accessible from s.BR(H/Agtt,mm) or BR(c02gtt1)/BR(c02gllR). • More work needed. ~ tan(b) via H/A mA = 300 GeV ~ ~ ~ 26

  27. 'Model-Independent' Masses ~ Similar process for t1 mass at high tan(b) Sparticle Expected precision (100 fb-1) qL 3% 02 6% lR 9% 01 12% ~ ~ ~ ~ • Alternative approach to CMSSM fit to edge positions. • Numerical solution of simultaneous edge position equations. • Note interpretation of chain model dependent. ~ ~ c01 lR ATLAS ATLAS Mass (GeV) Mass (GeV) • Use approximations together with other measurements to obtain 'model-independent' estimates of Wch2, scp, fsun etc. • Also provides model-independent measure of mc used with model-dependent comparisons (c.f. DAMA). ~ ~ c02 qL ATLAS ATLAS Mass (GeV) Mass (GeV) 27

  28. Direct DM Searches EDELWEISS CDMS DAMA ZEPLIN-I CRESST-II ZEPLIN-2 EDELWEISS 2 ZEPLIN-4 GENIUS XENON ZEPLIN-MAX • Next generation of tonne-scale direct Dark Matter detection experiments should give sensitivity to scalar WIMP-nucleon cross-sections ~ 10-10 pb. 28

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