Tevatron Searches for Higgs and SUSY Dan Claes

Tevatron Searches for Higgs and SUSY Dan Claes for the and collaborations Hadronic Structure 2007 September 3 -7 Comenius University Study and Congress Center Modra-Harmónia, Slovakia

Searches for contributions to observed events by Higgs decays as well as new phenomena beyond the Standard Model are intensifying as the Tevatron data set grows. CDF Chicago p p 1. 96 Te. V Booster CDF p DØ Tevatron p source p Main Injector & Recycler Proton-antiproton collider operating at COM energy of 1. 96 Te. V

Collider Run II Integrated Luminosity ~3 fb-1 recorded! All the results shown today are based on analysis of 1+ fb-1 Collider Run II Peak Luminosity 4 -8 fb-1 by 2009 Will run for at least two more years!

Higgs production at the Tevatron g g t t H t have seen evidence for single top! q q W/Z H one in ~1012 events could be a Higgs boson!

Nature appears to respect gauge invariance masslessness Through electroweak symmetry breaking within the complex scalar field, V( ), of the Higgs the gauge bosons W, Z acquire mass and a spin-0 Higgs boson appears, its own mass unspecified Higgs self-coupling diverges Allowed unstable vacuum though theoretical considerations do constrain it.

Direct searches reveal m. H > 114. 4 Ge. V/c 2 at 95% confidence The latest LEP Electroweak Working Group fit yields a preferred value of: A Standard Model Higgs should be LIGHT! m. H < 144 Ge. V at 95% confidence limit

Most sensitive searches: m. H<135 Ge. V/c 2 • produced with W or Z boson • decay to b quark pair H->WW Excluded at LEP bb Analysis Strategy m. H>135 Ge. V/c 2 • direct gg H production m. H < 135 Ge. V WH/ZH + H bb • decays to W boson pair m. H > 135 Ge. V Gluon fusion + H WW Background top, Wbb, Zbb WW, DY, WZ

electron/muon neutrino Selection - one or two tagged b-jets - e or with p. T > 15 Ge. V - ET > 20 Ge. V DØ: 4 non-overlapping samples - e or with - 1 “tight” or 2 “loose” b-tags CDF: 2 exclusive samples using different b-tagging algorithms

Limits set cutting on NN output: DØ exp, obs 95/ SM = 9. 05, 11. 1 CDF exp, obs 9. 95, 10. 1

ZH bb Selection: - two acoplanar jets (exactly 2 – CDF) - ≥ 1 tagged b-jets (CDF) 2 tagged b-jets (DØ) - ET > 55 Ge. V (CDF) 50 Ge. V (DØ) b jet

ZH bb Backgrounds : - W+heavy flavour jets - Z +heavy flavour jets - top pairs

Look for enhanced production of Zs: e, Selection: -require two isolated muons or electrons in Z mass window -one or two tagged b-jets CDF - corrects its b-jets with ET projections

1 ‘tight’ b-tag Separate NN trained to reject two main background processes: 2 ‘loose’ b-tags Z + jets 95/SM at MH = 115 Ge. V 20. 4 17. 8 exp 16 obs 16 top pairs

→ hadrons ee → e or same charge → e or Selection: - 2 isolated leptons (p. T > 15 Ge. V) (electrons and/or muons) like-sign! - kinematic likelihood selection , m , ET or di-lepton mass e min T “flips”: charge mis-identification estimated from data: : solenoid vs toroid e: solenoid vs (track, calorimeter)

ee e 20. 6 4. 0 18 5 data 19 15 5 WH(160) 0. 1 0. 2 0. 1 expected background 95/ SM ~ 18 for MH = 160 Ge. V L = 1 fb-1

Selection: - two isolated leptons - large ETmiss - Less than 2 jets (>15 Ge. V) CDF leptons will tend to align If WW comes from a spin-0 Higgs: small ( ) W W: large ( ) 16

Matrix Element Technique most sensitive at high masses

SUMMER 2006 • • Combines sixteen mutually exclusive final states for WH, ZH, WW - 10. 4 SM at m. H=115 Ge. V - 3. 8 SM at m. H=160 Ge. V Today I’ll report on recent progress – updated CDF & DZero low & high mass 1+ fb-1 analyses

Combines sixteen mutually exclusive final states for WH, ZH, WW 7. 7 SM at m. H=115 Ge. V 1. 4 SM at m. H=160 Ge. V

Higgs Bosons Beyond the Standard Model The Standard Model assumes a single complex Higgs doublet generates W/Z masses and a massive chargeless spin-0 boson, the Higgs, H 2 HDM: 2 Higgs Doublet Models • Hu/Hd couple to up- and downtype quarks • tan β is the ratio of their vev’s tan β = <Hu>/<Hd> • EWSB results in 4 massive scalar (h, H, H±) and one massive pseudoscalar (A) Higgs bosons ( ) Minimal Supersymmetric Model At large tan enhanced 0 bb and 0 tt couplings mean large Higgs production rates at hadron colliders! • fully parameterized (at tree level) by tanβ, m. A • with radiative corrections that depend on stop mixing

Fermiophobic Higgs Decaying to 3 A production mechanism unique to hadron colliders is accessible to the Tevatron provided m. H is not too large! For tan > 1, m. H < 200 Ge. V and mh < 90 Ge. V B(h ) 1 and B( H h. W ) 1 Background rates in 3 final state are very low • measured fake rates for Z or W • tri-photon production extrapolated from di-photon sample No obvious structure in diphoton mass spectrum Optimizing selection on 3 s ET > 30, 25 Ge. V 0 events observed 1. 1 0. 2 expected background

Fermiophobic Higgs Decaying to 3 Optimizing final selection on 3 s ET > 30, 25 Ge. V and p. T > 25 Ge. V rejects background Process Events expected direct 3 0. 9 0. 2 estimated 3 fakes 0. 3 0. 05 Observed 0 LEP 2 limits of 108 Ge. V/c 2 assumed SM coupling hf V V

Fermiophobic Higgs in 2 + X 1. 1 fb-1 Selection: 2 photons (p. T > 25 Ge. V) Background: , +jet and jet+jet mh>92 Ge. V at 95% CL

b (b) bb b(b) Search b g 0 b g b 0 At high tan Br(H/A bb) 90%, but swamped by QCD background Look for associated production with bs. Selection: - 3 b-tagged jets - look for a signal in the invariant mass of two leading jets The shape from double–tagged events ( mis-tagged rate) Normalized to the 3 b-tagged sample outside the signal mass window. ALPGEN MC

b (b) bb b(b) Search CDF found two useful discriminators • m 12 (invariant mass, 2 leading jets) • mdiff = mass of the tracks assigned to jet from the displaced vertex 0. 90 fb-1 0. 980 fb-1

Neutral MSSM Higgs had Main backgrounds: Z (irreducible), W+jets, Z ee, , mulijet, di-boson DØ: -channel only • 1 isolated separated from opposite sign hadronic • set of 3 NNs discriminate from jets CDF: e, , e+ channels • isolated e or separated from opposite sign hadronic • variable-size cone algorithm for > 55 Ge. V • mvis < 20 Ge. V removes • remaining W background • Ws removed by a cut on the MET projected on the bisector between s.

Neutral MSSM Higgs had Small excess in CDF’s e + channel • but < 2 effect • not observed in CDF e channel While DØ is in good agreement with SM

Neutral MSSM Higgs had Both experiments give similar results: in the 90<m. A<200 Ge. V region tan > ~40 -60 excluded for the no-mixing and mhmax benchmarks

SUPERSYMMETRY 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 h H A Z neutralino q l squark slepton The Lightest Supersymmetric Particle provides • ET if the LSP is stable and R-parity is conserved • photons and ET if the LSP is a gravitino and NLSP a neutralino • long-lived particles if the LSP decays weakly Symbol ~ g ~1, 20 ~1, 2, 3, 4 q~R, L ~l R, L SUSY particles are heavy • high p. T final state objects

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 M 2 tan U(1) U(2) gaugino mass parameter at EW scale higgsino mass parameter ratio of VEV of Higgs doublets • scalar sector described by MANY mass parameters • different SUSY breaking different class of models MSSM Assumptions: • SUSY particles are pair produced • Lightest SUSY particle (LSP) is stable SUSY Symmetry Breaking SUGRA( ~ 10 11 Ge. V) • 5 free parameters mo common scalar mass m 1/2 common squark mass Ao trilinear coupling tanb sign( ) • Lightest SUSY particle is

Stop charm + ET ~ with 0 as Lightest Supersymmetric Particle and R-parity pair production Search for: 2 charm jets plus Missing ET Pre-selection: 2 jets, p. T > 40(20) Ge. V Lepton, track vetos δφ(jj) < 165 o δφmax - δφmin < 120 o δφ(j, ET) > 50 o A=(ET-HT)/(ET+HT)>-0. 05 ET> 60 Ge. V then flavor tag (>= 1 jet)

Stop charm + ET Finally optimize mass-dependent cuts on HT and P = max + min For HT>140 P<320 SM process Number of events W l +jets Z +jets * W l +HF (bb, cc) Z +HF (bb, cc) WW, WZ, ZZ tt Single top Z ll(e, , )+jets Z ll(e, , )+ HF (bb, cc) 20. 62 2. 34 13. 23 1. 76 11. 94 1. 06 11. 60 0. 78 2. 70 0. 27 2. 17 0. 07 1. 76 0. 05 0. 12 0. 09 0. 04 Total BKG 64. 21 3. 22 Data 66 *use Z ee+jets to normalize Z vv+jets

Search for Long-lived Stop Some models predict long-lived massive particles due to: – weak coupling (e. g. , NLSP in SUSY models with GMSB) – Kinematic constraints (chargino in SUSY with AMSB) – New symmetry (gluino in split-SUSY, LSP stop in ED models) A long-lived, charged massive particle (CHAMP) appears as a “slow” muon. – High PT, low velocity, highly ionizing “muon” – Measure velocity ( ) via TOF detector + timing from tracking detector – Calculate mass from momentum and Electromagnetic Calorimeter (EM) CDF TOF Hadronic Tracking Calorimeter Chamber Muon Detector Control Region dominated by W Signal Region Data

Search for Long-lived Stop • Signal region: no candidates with m>120 • consistent with expected background Prospino 2 Exclude stable stop with m<250 Ge. V/c 2 at 95%CL

Squarks/Gluinos jets + ET Assuming R-partity is conserved, squarks and gluinos can decay directly into the LSP ( 01). or cascade down to the LSP The dominant signature for qg, gg + X is jets+E pp qq, T Separate 2 -jet, 3 -jet and >3 -jet analysis. At least 3 jets ET > 25 Ge. V and ET > 25 Ge. V

Squarks/Gluinos jets + ET 1. 4 fb-1 Mgluino < 290 for any Mq~ Mgluino < 380 excluded for Mg~ ~ Mq~ A 0=0 tan = 5 <0

Squarks/Gluinos jets + ET 0. 96 fb-1 ~ ~ Mgluino < 402 excluded for Mg~Mq Mgluino < 309 excluded – any Mq~ A 0=0 tan = 3 <0

Squarks had + jets + ET τ- Selection: • 2 or more jets ET > 35 Ge. V • ET > 75 Ge. V • at least one hadronic Optimization: • ET > 175 Ge. V • > 325 Ge. V A 0 = -2 m 0 tan = 15 <0 enhanced decay

Squarks had + jets + ET Predicted Yields Signal (m 0, m½) ( 80, 160) 4. 7 0. 4 (100, 150) 7. 1 0. 6 Background 1. 7 Data 2 Translating to LEP 2 slepton searches LEP 2 chargino searches

Chargino/Neutralino Trileptons Production of 1 02 will lead to trilepton final states with ET perhaps the cleanest signature of supersymmetry. Dominant backgrounds: Dibosons and Drell-Yan with converting bremsstrahlung photon ee+track • Limits set on Br as a ~ function of mass • Results interpretted within select m. SUGRA scenarios Large and Br ~ Maximal 3

Chargino/Neutralino Trileptons DØ ee+track: Final Selection Signal: 1 -2 events Background: 1 0. 3 Data: 0 DØ Combined Limit (5 analysis) : DØ Combined Limit (14 analysis) :

Conclusions