Search for large extra dimensions at the Tevatron V. Krutelyov (UCSB) for CDF and D0 Collaborations DIS-2008 Conference, London April 7-11, 2008 Large extra dimensions Direct graviton production  γ+MissingEnergy  jet+MissingEnergy  combination Virtual graviton exchange Outlook

4/09/2008V.Krutelyov Searches for LED at the Tevatron2 Large Extra Dimensions (LED) –Extra dimensions (ED) are predicted by string theories –Can stabilize the Higgs mass –Provide a dark matter candidate ED should not be visible to us –Compactification is a solution –Only gravity propagates in 4+d  ADD paradigm Each point would have additional dimension attached to it

4/09/2008V.Krutelyov Searches for LED at the Tevatron3 Large Extra Dimensions (LED)  ADD paradigm Large ED  compactified on a sub-millimeter scale R –Plank mass in (3+1)D related to the fundamental mass M D in 4+d M Pl 2 = 8π M D 2 *(M D *R) d –  Fundamental scale >~ TeV –  R ~ 0.1mm (1 fm) for d=2 (6) KK graviton mode mass ~ n/R –Practically continuous spectrum ΔM n,n+1 ~1/R: mEv (MeV) d=2 (6) N>>1 in HEP –in RS or UED ΔM ~ TeV  resonance

4/09/2008V.Krutelyov Searches for LED at the Tevatron4 LED: collider signatures Direct production –Signatures: jet+nothing (MET – missing E T ) γ + nothing (MET) –Cleaner, but suppressed by α QED / α QCD Single mode: σ(n)  1/M Pl 2  small –M Pl cancels out after sum over modes (n< n max ~ [M D *R]*[E max /M D ]): –σ  σ(n)*Sum  1/M D 2 *[s/M D 2 ] d/2 Virtual exchange –Signatures: Practically any pp(bar)  G  2 No resonance, shape enhancement only –Angular shape analysis to improve sensitivity Similarly, single mode * Sum –  σ  s/Λ 4 : Λ – cutoff scale of order M D

4/09/2008V.Krutelyov Searches for LED at the Tevatron5 Existing constraints Limits on M D from colliders (LEP/ Tevatron) are in 1TeV range –R < 0.2 mm for d=2 to R < 30 fm for d=6 Constraints from limits on modification of Newton law –Stronger than collider limits for d=2: R 3.6 TeV Stronger constraints for d<4 from astrophysics [PDG 2007] –Up to R< m (700 TeV) for d=2 from neutron stars –Many assumptions about star internals, sensitive only to low n/R  This limit can be relaxed while collider limits are the same CDF: PRL 97, (2006)PRL 97, (2006) CDF Run II (368 pb -1 ) nM D (TeV)R(mm) 2>1.18<0.35 3>0.99<3.6x >0.91<1.1x >0.86<3.5x >0.83<3.4x10 -11

4/09/2008V.Krutelyov Searches for LED at the Tevatron6 LED in jet + MET Data sample of 1.1 fb -1 –collected with a jet trigger with E T >100 GeV Data-driven estimates of the major backgrounds. Electroweak (jet + Z  νν and W  v: not identified) QCD (mismeasured jets) is smaller -- ~6% of total background Selections: –Leading jet E T > 150 GeV 2 nd leading jet E T (2) < 60 GeV to increase acceptance (ISR/FSR) –MET > 120 GeV, away (in φ) from any jet –No isolated tracks (P T > 10 GeV) to remove W(  ν)+jets

4/09/2008V.Krutelyov Searches for LED at the Tevatron7 LED in jet+MET: example event in data Jet E T = 419 GeV, MET = 417 GeV Calorimeter E T (η,φ) lego view Detector (r,φ) side view CDF Run II Preliminary

4/09/2008V.Krutelyov Searches for LED at the Tevatron8 LED in jet+MET: results nM D (TeV)R(mm) 2> 1.31< > 1.08< 3.15 x > 0.98< 1.01 x > 0.91< 3.20 x > 0.88< 3.16 x BackgroundExpected Events Z  ν ν 390 ± 30 W  τν 187 ± 14 W  μν117 ± 9 W  e ν58 ± 4 Z  l l6 ± 1 QCD23 ± 20 γ Jet17 ± 5 Non-Collision10 ± 10 Total Predicted808 ± 62 Data Observed809

4/09/2008V.Krutelyov Searches for LED at the Tevatron9 LED in γ+MET: Photon selection Events with high-E T photon + nothing Important to suppress non-collisions/fake photons D0 Photon pointing –Fine segmentation of EM calorimeter to separate real photons from cosmic and jet backgrounds CDF Photon Timing –~x20 suppression of cosmics ~6ns/132ns (signal Δt)/(calorimeter input Δt) efficiency ~100% for photons from collisions Topological cuts: Beam halo is negligible –Cosmics suppressed ~x30 more After ~x600 suppression cosmics are still 20% of the total background

4/09/2008V.Krutelyov Searches for LED at the Tevatron10 LED in γ+MET: data Similar selections –photon E T > 90GeV –|eta|<1 –Jet/high-P T track veto D0: arXiv: v1arXiv: v1 ETET

4/09/2008V.Krutelyov Searches for LED at the Tevatron11 LED: constraints from γ+MET Updates with more data expected soon d, LED Observed (expected) 95% CL lower limit on M D in GeV CDF preliminary 2 fb -1 D0 preliminary 1 fb (1000)884 (921) (940)864 (877) 4970 (910)836 (848) 5930 (880)820 (821) 6900 (860)797 (810) 7797 (801) 8778 (786) D0: arXiv: v1arXiv: v1

4/09/2008V.Krutelyov Searches for LED at the Tevatron12 LED in γ+MET and jet+MET combined Limits from jet+MET and γ+MET combined give better sensitivity Similar sensitivity in jet+MET and γ+MET for d>3 Tevatron combination is en course NB: from Newton law tests M D > 3.6 TeV for d=2

4/09/2008V.Krutelyov Searches for LED at the Tevatron13 Virtual G exchange:  γγ/ee/μμ High mass γγ/ee/μμ final state –Look for smooth excess at high mass Set limits based on (M,|cosθ * |) Limits on mass scale Λ in TeV Nucl.Phys. B544, 3(1999) Phys. Rev. D59, (1999)PRL 82, 4765 (1999) d=2d=3d=4d=5d=6d=7λ=1 γγ/ee 200 pb  246 pb -1 PRL (2005) PRL (2005)

4/09/2008V.Krutelyov Searches for LED at the Tevatron14 Virtual G exchange:  ZZ ZZ  4ℓ from D0 (1fb -1 ) –  σ (pp  ZZ) < 4 pb At 95% C.L. –arXiv: arXiv: ZZ  4ℓ/2ℓ2ν from CDF (2 fb -1 ) –  σ(pp  ZZ) = 1.4 ± 0.7 pb >4 σ evidence –arXiv: v1arXiv: v1 Can expect limit on Λ in TeV range K:arXiv: v5arXiv: v5 Λ [GeV]

4/09/2008V.Krutelyov Searches for LED at the Tevatron15 Outlook No evidence for large extra dimensions has been seen –Same for other kinds of ED Both direct production and virtual exchange of LED graviton are explored –Sensitivity to the fundamental mass scale is M D >~ 1 TeV in direct production Λ>~ 1.5 TeV in virtual exchange Looking forward to more data D0: arXiv: v1arXiv: v1

4/09/2008V.Krutelyov Searches for LED at the Tevatron16 BACKUP SLIDES

4/09/2008V.Krutelyov Searches for LED at the Tevatron17 LED

4/09/2008V.Krutelyov Searches for LED at the Tevatron18 Large extra dimensions Gravitational Potential in 4 Dimensions (Newton) n extra dimensions, compactified at radius R r<<R r>R At large distances, must return to original potential (M PL ) 2 ~ R n (M D ) 2+n