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

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

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

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

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

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

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

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

List of EFT Operators describing WIMP-SM interactions J. Goodman et al Dirac Fermions Complex Scalars Real Scalars scalar vector axial -vector tensor 9

List of EFT Operators describing WIMP-SM interactions J. Goodman et al Dirac Fermions scalar vector axial -vector tensor 10 Spin dependent Spin-independent

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

The ADD model Phys. Lett. B 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 ~ 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

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

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

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

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

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

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

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

CMS Barrel Muons return yoke muon chambers 20

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

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

Monojets in ATLAS at 8 TeV 23

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

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

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

Monojets An event at 8 TeV 27

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

Signal Region SR1 > 120 geV 29

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

31 Monojet Production Cross Section Limits GeV

M* limits based on 350 GeV signal region. 32

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

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

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  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

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

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

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

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

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

Event Selection primary vertex Photon E T > 150 GeV |  | < 2.0 E T miss > 150 GeV |  | < 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

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

Mono  Results in ATLAS 43

Mono   -nucleon xsec limits 44

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

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

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

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

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

Mono  Results in CMS 50

D8 operator D5 operator 51

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

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

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

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

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

Summary CMS/ATLAS analyses searched for Dark Matter WIMPs in the context of Effective Field Theory & Large Extra Dimensions Data sets include 5 fb 7 TeV 10 fb -1 & 20 fb 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

58 Backup

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)

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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