SUGRA Searches at the Tevatron Dan Claes University

SUGRA Searches at the Tevatron Dan Claes University of Nebraska representing the CDF and D 0 Collaborations The Conference on Higgs & Supersymmetry Laboratoire de l'Accélérateur Linéaire Orsay, France March 19 -22, 1999

a = (g-2)/2 a (SM)=11 659 159. 6(6. 7) 10 -10(0. 57 ppm) a (SM)-a (exp)= 43(16) 10 -10 “Precise measurement of the positive muon anomalous magnetic moment” (submitted to PRL February 23, 2001) “We are now 99 percent sure that the present Standard Model calculations cannot describe our data. ” “Many people believe that the discovery of supersymmetry may be just around the corner. We may have opened the first tiny window to that world. ”

Though just 5½ years ago. . .

Fig. 2 Rb and Rc data [2] and the SM predictions [5].

SUPERSYMMETRY New symmetry unifying particles of different spin within multiplets -solves “fine-tuning” provided MSUSY < 1 Te. V -allows unification of the gauge couplings -includes quantum gravity

Particle Name gluon charged Higgs charged weak boson light Higgs heavy Higgs pseudoscalar Higgs neutral weak boson photon quark lepton Symbol g H Spartner Name gluino chargino Symbol ~ g ~1, 2 W h H A Z g q l neutralino Z 1, 2, 3, 4 squark slepton q~R, L ~ ~ l. R, L

Minimal Supersymmetric SM Extension adding the fewest new particles • 2 Higgs doublet h 0 H 0 A 0 H + • and described by 4 parameters M 1 U(1) M 2 U(2) gaugino mass parameter at EW scale higgsino mass parameter tan ratio of VEV of Higgs doublets • scalar sector described by MANY mass parameters • different SUSY breaking models different class of

MSSM Assumptions: • SUSY particles are pair produced • Lightest SUSY particle (LSP) is stable

SUSY Symmetry Breaking 11 SUGRA (L 10 Ge. V) • 5 free parametersmo common scalar mass m 1/2 common squark mass Ao trilinear coupling tan sign( ) • Lightest SUSY particle is

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay Signal Cross Sections g g q g Production has less dependence on SUSY parameters than decays Squarks/gluinos dominant if kinematically accessible Cross sections for scalar leptons are small

Daniel Claes, University of Nebraska-Lincoln g q* g Higgs SUSY Conference 2001, Orsay q q q q g q q If light, squarks and gluinos should be copiously produced at the Tevatron

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay Assuming R-partity is conserved, squarks and gluinos can decay directly into the LSP ( 01). 0 1 0 1 q g q q q or cascade down to the LSP q g q 0 2 q q 0 1 q g q q q q q 1 q 01 qg, gg + X is jets+E So that the dominant signature for pp qq, T q q

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay The 1992 -1994 Tevatron Run Cross sections for new physics is small compared to Standard Model processes But CDF and D 0 both recorded over 100 pb-1 of data

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay The 1992 -1994 Tevatron Run DØ Precision tracking: vertexing, b-tagging, lepton identification Powerful calorimetry: e, g, ET

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay D 0 MET and Jets Analysis jets + E pp q, g T • large branching ratio, but suffers from enormous backgrounds • QCD multijet events w/faked ET • W/Z+jets • tt Used ET trigger, basic selection criteria: • ETj 1>115, ETj 3>25 Ge. V • ET>75 Ge. V • jets and ET not aligned • HT( i >1 Ei. T) > 100 Ge. V • veto isolated with PT > 15 Ge. V Reduce QCD Reduce W/Z

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay Jet-ET Correlations Jet 1 1 Low Et JET MIN Trigger with offline Met > 10 Ge. V cut 3. 0 2. 5 2. 0 Jet 3 3 1. 5 1. 0 ET 0. 5 Jet 2 0. 0 0 0. 5 1. 0 1. 5 2. 0 2. 5 3. 0 MET, Jet 1 vs MET, Jet 2

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay Jet-ET Correlations

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay D 0 MET and Jets Analysis Final ET, HT cuts tuned to optimize S / B across (m 0, m 1/2) plane 79 pb-1 of data analyzed Expected: 8. 3 3. 5 events Observed: 15 Mq~ > 250 Ge. V (95% C. L. ) Mg~ > 260 Ge. V (Mg~=Mq~) Mg~ > 300 Ge. V (small mo) Phys. Rev. Lett. 83 4937 (1999); hep-ex/990213

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay D 0 MET and Jets Analysis Mq~ > 250 Ge. V (95% C. L. ) Mg~ > 260 Ge. V (Mg~=Mq~) Mg~ > 300 Ge. V (small mo) Phys. Rev. Lett. 83 4937 (1999); hep-ex/990213

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay CDF MET and Jets Analysis starting with basic cuts similar to DO Missing ET trigger • cleanup jets projected to calorimeter gaps Blind Box method defines signal region by: • ET>70 Ge. V • HT( i >1 Ei. T) > 150 Ge. V • Ntrkiso (isolated tracks)=0 • indirect lepton veto

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay ET predominantly from mis-measured QCD events

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay QCD ET comparison: data(JET 20+JET 50) & predictions(Herwig)

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay CDF MET and Jets Analysis Main backgrounds QCD, W/Z+jets, tt

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay CDF MET and Jets Analysis Expected: 76. 02± 12. 8 events Observed 74

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay CDF MET and Jets Analysis Expected: 76. 02± 12. 8 events Observed 74 For mq~ mg~ mg > 300 Ge. V/c 2 For mq~ << mg~ mg > 570 Ge. V/c 2 For mq~ >> mg~ mg > 195 Ge. V/c 2

Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France CDF Dilepton + Jets Search Squark & gluino cascade decays can also lead to dilepton final states ~~ ~ ~0 +jj pp q, g 1 2 jj + ET g ~ q ~ 02 ~ 1 ~ q q ~01 Z* W* ~01 Selection cuts on CDF’s dilepton trigger: 2 isolated leptons, PT > 11, 5 Ge. V 2 central jets ET > 15 Ge. V, | | < 2. 4 ET > 15 Ge. V q q

Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France CDF Dilepton Backgrounds Heavy quark and di-boson production Require LS leptons. Final M cut rejects Z-production.

Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France CDF Dilepton + Jets Search Expect: 0. 55 0. 25 0. 08 events Observe: 0 events

Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France Dilepton m. SUGRA Search ~01 Squark and gluino search through dilepton final states pp SUSY jj + ET g ~ q ~ 02 ~ 1 ~ q q Z* W* ~01 q q Selection, optimized for different regions of m. SUGRA parameter space, made by (52 different) combinations of ETjet 1, 2 > 20 Ge. V or 45 Ge. V (optionally, also require ETjet 3 > 20 Ge. V) ee signatures: ETe 1 > 17 Ge. V, ETe 2 > 15 Ge. V em signatures: ETe > 17 Ge. V, ET > 4 Ge. V, 7 Ge. V or 10 Ge. V mm signatures: ET 1 > 20 Ge. V, ET 2 > 10 Ge. V ET > 20, 30, or 40 Ge. V

Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France Dilepton m. SUGRA Search Background sources • QCD Multijet, W+jets • estimated from data • t t , Z + jets SPYTHIA-based Monte Carlo (FMC 0) 108 pb-1 of data analyzed Mg~ = Mq~ > 255 Ge. V 95% C. L. for tan = 2

Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France Charginos and Neutralinos ~ ~ Production of 1 02 will lead to trilepton final states with ET perhaps the cleanest signature of supersymmetry. q ~ ~ pp q, g 1 02 + ET ~ 1 q ~ q* q ~ 0 2 W* ~ 1 ~ 0 q 2 ~01 ~ ~ 1 ~01 W* Z* ~01 ~ ~ 02 * ~01

Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France Trilepton + Jets Search Very low background • Drell-Yan + fakes • heavy flavor production • ZZ, WZ Both CDF and DO searched for trileptons (e, ) in Run I PRL 80, 1591 (1998); PRL 80, 5275 (1998) Selection cuts : 3 (e, ) with PT > 5 - 22 Ge. V require Opposite Sign Leptons (CDF) ET > 10 - 15 Ge. V mass and topological cuts

Daniel Claes, University of Nebraska Lincoln Higgs SUSY Conference 2001 Orsay, France Trilepton + Jets Search CDF Expected: 1. 2 0. 2 Observed: 0 DO Expected: 1. 3 0. 4 Observed: 0 100<m 0<2500 Ge. V/c 2 a) m½=50 Ge. V/c 2 b) m½=75 Ge. V/c 2 c) m½=100 Ge. V/c 2 d) m½=120 Ge. V/c 2

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay Run II Upgrades Run II has begun with Accelerator upgrade Run II total integrated luminosity 120 pb-1 2 fb-1 /2 years (20 fb-1 extended run) instantaneous luminosity 4 - 20× 1030/cm 2 sec 2× 1032/cm 2 sec bunch crossing intervals 3. 8 sec • Fermilab’s Main Injector (commissioned June 1999) • New anti-proton storage ring 132 nsec DØ CDF Tevatron beam energy 1. 8 Te. V 2. 0 Te. V • complemented by major detector upgrades Main injector

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay The DO Detector Upgrade • retain the uranium/liquid-argon calorimeter • retain most of its full-coverage muon system But the entire tracking volume is being replaced • shorter bunch spacing, • higher radiation levels New Detector Elements • inner silicon vertex detector • 8 layers of scintillating fiber tracking • 2 Tesla superconducting solenoid • scintillator-based preshower detecto

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay DO Upgraded Triggering • LEVEL 1 (trigger decisions within few sec) • calorimeter trigger unchanged • new fiber tracker trigger • adds new preshower detector • LEVEL 2 (trigger decisions within 100 sec) • global processors run algorithsm • correlating info from different subdetectors • e. g. , calorimeter-preshower-track matches • E/p and invariant mass cuts • Event buffering between each trigger stage • deadtime due to pileup decreased • event transfer rates into LEVEL 3 1 k. Hz • LEVEL 3 • rejection of 50 • average processing time < 100 msec)

The number of anti-protons in the ring has been one of the major limiting factors in Tevatron luminosity. The anti-proton stacking rate will be increased to 2 x 1011/hr from 7 x 1010/hr The machine will operate with 36 x 36 bunches (396 ns spacing) initially and (132 ns) eventually. Run II machine goals: 1) Run IIa to achieve a luminosity of 5 x 1031 cm-2 s-1 and an integrated luminosity of 2 fb-1 2) Run IIb to achieve a luminosity of 2 x 1032 cm-2 s-1 and an integrated luminosity of ~20 fb-1

Time-offlight added COT replaces CTC End Plug extended to larger SVX replaced, Si layer added to beampipe, Intermed. Si Layers added Forward calorimeter eliminated Shower max edded • a new massive silicon vertex detector + New Trigger, DAQ – 7 layers extending to 28 cm in radius – deadtime-less SVX 3 readout electronics • a new central outer tracker (COT) • hermetic scintillator tile plug & forward calorimeter • large trigger bandwidth

Forward Minidrift chambers Central Scintillator Forward Scintillator Shielding New Solenoid & Tracking: Silicon, Sci. Fi, Preshowers • entirely new tracking + New Electronics, Trigger, DAQ – 2 T super conducting solenoid – disk/barrel silicon detector – 8 layers of scintillating fiber tracker – preshower detectors • improved muon spectrometer • new trigger and DAQ system

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay Run. II Squark and Gluino Prospects • Multijets with ET remains the dominant signature of q~’s & g~’s Critical • Understanding the tail of the ET distribution in multijet events • Methods to accurately estimate multijet backgrounds ~ ~ ~ • Large tan : enhanced g / i / 0 i decays to 3 rd generation particles Critical • -lepton and b-quark trigger and • identification capabilities.

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay Run. II Squark and Gluino Prospects Run II improvements: 1) improved ET resolution – more hermetic calorimeter (CDF) – better vertexing (DØ) 2) Advanced analysis methods, improved tools With 2 fb-1, DØ and CDF will probe m 1/2 up to ~150 Ge. V corresponding to Mgluino 400 Ge. V (for m 0<200 Ge. V)

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay Chargino and Neutralino Prospects Trilepton signatures with large content Major backgrounds: W+jets, Z+jets, WZ, … Critical: large acceptances and high efficiencies for high & low p. T leptons including

Daniel Claes, University of Nebraska-Lincoln Higgs SUSY Conference 2001, Orsay Chargino and Neutralino Prospects Run II improvements: 1) extended coverage improves lepton acceptances 2) lepton charge and better momentum measurements reducing backgrounds (DØ) 3) new preshower detectors 4) major effort on identification built upon Run I experiences Mchargino reach >150 Ge. V for most of parameter space Mchargino reach ~200 Ge. V for small to medium values of tan