1. Searches for Dark Matter & Large Extra Dimensions in Mono-Jet/  /W/Z Signals in the ATLAS & CMS Detectors Daniel S Levin – University of Michigan MASS2013 On behalf of the ATLAS & CMS Collaborations 1

2. 1. Why we search 2. Mono-X experimental signatures Effective Field Theory Large Extra Dimensions SUSY Wimps, invis. Higgs Wh or Zh with h   not covered here 3. LHC 4.Analysis Method 5. ATLAS & CMS Detectors 6. Signals, Backgrounds, Data selection, Results mono-jets mono-  mono-W mono-Z Outline 2

3. Dark Matter inferred from Gravitational Signatures Galactic rotation curves Galactic velocities in galactic clusters Zwicky: clusters have very large mass to light ratios Gravitational lensing Bullet Cluster Total vs Baryonic Centers of Mass differ by 8 σ NASA Large scale structure: “A filament of dark matter between two clusters of galaxies” Dietrich et al, July 2012 Nature 3

4. Three (non-gravitational) DM Detection Methods 1.Direct detection from astrophysical sources:  Nuclear recoil from DM particle interactions Positive results: from DAMA, COGENT/LIBRA08, CDMS (Excluded by: Xenon100 … ) 2.Indirect astrophysical detection  Search for products of WIMP annihilation  Observations of positron excess: HEAT, PAMELA, AMS  Wimp-WIMP annihilation 3.Production of DM in LHC & Tevatron collisions  Search for generic decay signatures q q q q q q 4

5. Three (non-gravitational) DM Detection Methods 1.Direct detection from astrophysical sources:  Nuclear recoil from DM particle interactions Positive results: from DAMA, COGENT/LIBRA08, CDMS (Excluded by: Xenon100 … ) 2.Indirect astrophysical detection  Search for products of WIMP annihilation  Observations of positron excess: HEAT, PAMELA, AMS  Wimp-WIMP annihilation 3.Production of DM in LHC & Tevatron collisions  Search for generic decay signatures q q q q q q 5 Suggestive but inconclusive

6. X contact interaction  -q-q q Events characterized by ISR recoil of X X= triggerable object  jet, , W, Z 6

7. Mono-X final states extracted from an Effective Field Theory:  a heavy particle (M > M  ) mediates the  + q/g interaction  EFT only valid for energies < M  high energy underlying behavior integrated out scalar, vector, axial vector & tensor operators: D1, D5,D8 D9  = Dirac fermion DM particles  I suppression scale or interaction strength Interactions are detectable: jet, photon, W, Z emitted as ISR DM Production in EFT L = Example of interactions used arXiv 1212.3352 7

8. In Effective Field Theory:  mediator dark sector particle is M  interaction strength (or suppression scale)  or M * ~ M/(g 1 g 2 ) 1/2 WIMP mass = m  4-momentum conservation requires: m  < M/2 Perturbation theory requires: g 1 g 2 < (4  ) 2 combine to get m  < 2  M * 8

9. List of EFT Operators describing WIMP-SM interactions J. Goodman et al http://arxiv.org/abs/1008.1783v2 Dirac Fermions Complex Scalars Real Scalars scalar vector axial -vector tensor 9

10. List of EFT Operators describing WIMP-SM interactions J. Goodman et al http://arxiv.org/abs/1008.1783v2 Dirac Fermions scalar vector axial -vector tensor 10 Spin dependent Spin-independent

11. Large Extra Dimensions Planck scale M Pl ~ O(10 19 ) GeV Electroweak unification scale O(10 2 ) GeV Arkani-Hamed, Dimopoulos, and Dvali address the enormous difference between the: © Cartoon by Mike Lester 11

12. The ADD model Phys. Lett. B429 1998 postulates the presence of n extra spatial dimensions- size R, defines a fundamental Planck scale in 4 + n dimensions: M D where M Pl 2 ∼ M D 2+n R n A choice of R for a given n yields an M D at the electroweak scale. for n=2, M D ~ 100-1000 GeV  R ~ mm Extra spatial dimensions are compactified: yields a Kaluza-Klein tower of massive graviton modes. At the LHC graviton modes may be excited in extra dimensions, & appear as non-interacting particles in 4 –space, with a jet, or photon,  a monojet signature in the final state. Large Extra Dimensions 12

13. Beyond SM Predictions E T miss Analysis Strategy 13 1) Look for a clean signature: high momentum object with large Missing E T 2) backgrounds understood via MC, data driven methods 3) kinematic cuts define Signal Regions 4) count number of events in Signal Regions  look for excess over SM background Max Baak- CERN

14. Photo: D. Levin LHC ATLAS CMS 14 1200 dipoles at 8.4 T N p = 10 11 Bunch crossing: 25 ns L = 27 km 4.7 km

15. LHC Operations CMS mono jet ATLAS mono W, Z ATLAS/CMS mono  ATLAS/CMS mono jet 15

16. Inner tracker EM Calorimeter Hadron Calorimeter Toroid magnets Muon system ATLAS Detector 16

17. EMCAL: LAr-Pb HCAL: scintillating tiles barrel LAr endcaps 17

18. 1200 MDT + TGC & RPC chambers Six story (45 X 22 m) structure  P/P = 3% @ 100 GeV 10% @ 1 TeV Sagitta at 1 TeV = 500  m  50  m error ATLAS Muon Spectrometer 747 18

19. Fun facts Weight 12,500 t Diameter 15. m length 21.6 m B field 4 T superconducting coil 4T calorimeters tracker muon barrel muon endcaps return yoke CMS Detector 19

20. CMS Barrel Muons return yoke muon chambers 20

21. CMSATLAS Tracker EMCAL HCAL Muon Spectrometer Combined tracking  /P T = 1%-10% at 50 -1000 GeV |  | <2.4 Combined+ Standalone tracking  /P T = 2%-to 10% at 50 -1000 GeV |  | <2.7 B field4 T Solenoid + yoke2T Solenoid, 0.5-1 T Toroid CMS - ATLAS Comparison 21

22. A rush hour pileup ! a Z   event… with 25 interaction vertices

23. Monojets in ATLAS at 8 TeV 23

24. EFT operators (representative D 5, D 8, D 11 ) pp   q + X and pp   g + X with Madgraph5 and Pythia8 (CTEQ6L1 pdf) DM Masses: M  = 1 – 2000 GeV in 10 points. Monojets Signal Generation ADD Large Extra Dimensions Model: Dimensions n =2-6 Planck mass: M D = 2-5 TeV with Pythia 8 & CTEQ6.6 pdfs. Full ATLAS detector simulation with GEANT4 24

25. Event Selection Require primary vertex Leading jet P T > 120 GeV |  | < 2.0 At most 2 jets P T > 30 GeV |  | < 4.5  (jet, E t miss ) > 0.5 Lepton veto 25 Signal Regions GeV

26. Monojet Backgrounds Z  + jets 50% W  l + jets (with one lepton undetected) 46 % Z  ll + jets, multijet, single t, tt dibosons… 4% Electroweak backgrounds determined from Control Regions (orthogonal to Signal Regions)- reversal of one cut: eg. for Z  +jets CR has final state lepton and otherwise same requirements on jet P t, E t miss, subleading jet vetos, etc QCD backgrounds estimated from jet enriched data sample Top and diboson backgrounds from MC 26

27. Monojets An event at 8 TeV 27

28. Monojet Control Region Examples Transverse mass GeV E T miss GeV Z(   ) +jets Control Region W(   ) +jets Control Region 28 diboson & top bkg in CR removes lepton veto Background estimation

29. Signal Region SR1 > 120 geV 29

30. SR2 > 220 GeV SR4> 500 GeV SR3 > 350 GeV 30 More Signal Regions

31. 31 Monojet Production Cross Section Limits 120 220 350 500 GeV

32. M* limits based on 350 GeV signal region. 32

33. Limits on M* converted to limits on  WIMP-Nucleon Phys.Rev.D82:116010,2010 (these limits from 2011 data) 33 WIMP mass range limits extended to 1 GeV

34. Limits on ADD Model For n=6, limit on M D = 2.7  0.1 TeV For n=2, limit on M D = 4.2  0.4 TeV 34

35. EFT operators  vector D 5, A-V: D 8, scalar D11 (DM –gluon) pp   q + X and pp   g + X with Madgraph and Pythia6.42 (CTEQ6L1 pdf) DM Masses: M  =1, 10, 200, 400, 700, and 1000 GeV Mediator Mass  50-500 GeV Monojets Signal Generation ADD LED Model: Extra Dimensions n =2-6 with Pythia 8 & CTEQ6.6 pdfs. Monojets in CMS 19.5 fb -1 at 8 TeV 35

36. CMS Monojet Event Selection One well constructed primary vertex Leading jet P T > 80 GeV |  | < 2.6 At most 2 jets P T > 30 GeV |  | < 4.5  (jet1, jet2 ) < 2.5 (suppress QCD dijets) Lepton veto Seven signal regions: 36

37. spin independent vector operator (eg., D5) spin dependent axial-vector operator (eg., D8 ) Limits on the contact interaction scale, Λ, as a function of the DM mass (Λ same as M * used for ATLAS results) 37

38. Limits on  (WIMP-nucleon) extends to 1 GeV spin independent vector operator (eg., D5) spin dependent axial-vector operator (eg., D8 ) 38

39. spin independent scalar operator (eg., D11 ) Limits on WIMP-nucleon interaction cross section 39

40. Lower limits on M D versus the number of extra dimensions CMS limits on M D higher than ATLAS 40

41. Event Selection primary vertex Photon E T > 150 GeV |  | < 2.0 E T miss > 150 GeV |  | < 4.5 0 or 1 jet P T > 30 GeV |  | < 4.5  (jet/ , E t miss ) > 0.5 Lepton veto Object isolation Mono  in ATLAS 4.7 fb -1 at 7 TeV 41

42. Mono  Backgrounds in ATLAS Z  +  68% W  l +  (undetected lepton) 18 % Z/W+jets 13% Electroweak backgrounds from Control Region Invert  veto  use to normalize the W+  & Z+  MCs 42

43. Mono  Results in ATLAS 43

44. Mono   -nucleon xsec limits 44

45. Mono jet - mono  comparison to direct WIMP production Spin dependent Limits comparable  but mono-jet overall is lower Mono-jet Mono-  45

46. Mono jet/mono  comparison to direct WIMP production Spin independent mono-jet channel sensitive to D11 gluon operator Mono-jet Mono-  46

47. Event Selection require well defined primary vertex Photon P T > 145 GeV |  | < 1.44 (barrel region only) Energy ratio: ECAL/HCAL <0.05 in cone  R<0.15 lepton & hadronic activity veto object isolation Single signal region: E T miss > 130 GeV |  | < 4.5 Mono  in CMS 5.0 fb -1 at 7 TeV 47

48. Mono  Backgrounds in CMS Backgrounds determined from MC: Z/    jet di-   Pythia6 + CTEQ6L1 W   Madgraph Z   +  60% W   l + , di- ,  +jet 6 % Z/W+jets +other 34% Predicted Signal Region background = 75.1  9.5 events Observed = 73 events 48

49. p T γ =384 GeV, MET=407 GeV. Mono  49

50. Mono  Results in CMS 50

51. D8 operator D5 operator 51

52. Representative operators are C1, D1, D5, D9 D5 generated for constructive C(u)=-C(d) and destructive C(u)=C(d) cases 52 Advantage: For W radiation, interference between diagrams. If equal couplings- but opposite signs (C(u) = -C(d) )  W can become dominant

53. Two signal regions: E t miss = 350, 500 GeV 53

54. Backgrounds estimated from Z+jets, W+jets Control Region: lepton veto inverted Jet selection intact 54

55. Data (W+Z) & predicted background in the Signal Regions E t miss 350 GeV, 500 GeV 55 M * GeV

56. New ATLAS mono Z/W limits:  WIMP-Nucleon for D5 and D9 operators 56

57. Summary CMS/ATLAS analyses searched for Dark Matter WIMPs in the context of Effective Field Theory & Large Extra Dimensions Data sets include 5 fb -1 @ 7 TeV 10 fb -1 & 20 fb -1 @ 8 TeV All data in the signal regions consistent with SM backgrounds. Limits set on array of EFT operators and modified Planck Mass M D “ … it should be borne in mind that our limits strictly speaking only apply when all mediator masses are much larger than the typical energy of the reaction … in the absence of a picture of the UV theory, it is hard to know whether the bounds are over- or under-estimated when the effective theory description does not strictly apply. “ J. Goodman et al arXiv 1008.1783 57

58. 58 Backup

59. Fitting PAMELA positron excess with Dark Matter 200 GeV Wino-like neutralino (Grajec, Kane, Pierce, Watson) M. Schubnell U. Michigan A nearby pulsar (Geminga) (Yuskel, Kistler, Stanvev)

60. Mono  Backgrounds in ATLAS Z  +  68% W  l +  (undetected lepton) 18 % Z/W+jets 13%  data driven method 60 1.Sample of Z boson used to determine fraction of electrons that reconstruct as photons. 2.This fraction is used to determine rate for which W+jets occurs in the signal region – where an electron is accepted instead of a photon. This results in a total W(! eν)+jet background estimation of 14 ± 6 events, where the uncertainty is dominated by the limited size of the control data sample.

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