Tevatron Searches for Higgs and SUSY for the andcollaborations Dan Claes 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 Main Injector & Recycler Tevatron Chicago   p source Booster pp p p pp 1.96 TeV CDF DØ Proton-antiproton collider operating at COM energy of 1.96 TeV

Collider Run II Peak Luminosity Collider Run II Integrated Luminosity Running approved through 2009 All the results shown today are based on analysis of 1+ fb -1 ~3 fb-1 recorded per experiment ! 6 – 7 fb -1 expected per experiment

one in ~10 12 events could be a Higgs boson! have seen evidence for single top! g g t t t H W / ZW / ZW / ZW / Z H q q Higgs production at the Tevatron

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

m H < 144 GeV at 95% confidence limit The latest LEP Electroweak Working Group fit yields a preferred value of: Direct searches reveal m H > GeV/c 2 at 95% confidence A Standard Model Higgs should be LIGHT! giving the indirect constraint:

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

50 % efficiency, 1.5 % mistag (loose) 40 % efficiency, 0.5 % mistag (tight) 70 % efficiency 4.5 % mis-tag (loose tag) 50 % efficiency 0.3 % mis-tag (tight tag) In low mass H->bb search - Identifying b-jets is essential! - S/B improves ~1:1000 -> 1:100 - Requiring two b-jets: S/B ~ 1:50 DCA Decay Length B-tagging Transverse Plane impact parameter-based (track DCA) secondary vertex reconstruction reconstructed info from above (track multiplicity, pT, vertex, decay length, mass) can be fed into a Neural Net primary vertex Using Neural Net:

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

 95 /  SM = 9.05, , 10.1 DØ exp, obsCDF exp, obs Limits set fitting the NN output: m H (GeV/c 2 ) at m H =115 GeV/c 2

Selection: - two acoplanar jets (exactly 2 – CDF) - ≥ 1 tagged b-jets (CDF) 2 tagged b-jets (DØ) - E T > 55 GeV (CDF) 50 GeV (DØ) b jet ZH  bb b jet Backgrounds : - W+heavy flavour jets - Z +heavy flavour jets - top pairs

ZH  bb  95 /  SM = 9.7 ( expected M H =115 GeV/c 2 L = fb -1

Selection: -require two isolated muons or electrons in Z mass window -one or two tagged b -jets e,e, Look for candidates in the Z-peak: e,e, CDF - corrects its b -jets with E T projections to improve m jj resolution

Separate NN trained to reject two main background processes: Z + jetstop pairs 1 ‘tight’ b -tag 2 ‘loose’ b -tags at M H = 115 GeV  95 /  SM 20.4 exp obs 16 m H (GeV/c 2 )

→ anything → e or  same charge di-lepton mass Selection: - 2 isolated leptons (p T > 15 GeV) (electrons and/or muons)‏ - kinematic likelihood selection ee ee  “flips”: charge mis-identification estimated from data:  : solenoid vs toroid e : solenoid vs  (track,calorimeter) like-sign! , m, E T or  T min HW  WWW  + X

ee e   expected background data WH(160)  95 /  SM ~ 18 for M H = 160 GeV L = 1 fb fb -1 HW  WWW  + X

17 Selection: - two isolated leptons - large E T miss - Less than 2 jets (>15 GeV) CDF If WW comes from a spin-0 Higgs Higgs: small  ( ) W W: large  ( ) leptons will tend to align 1.9 fb -1

Matrix Element Technique most sensitive at high masses  95 /  SM ~ 3.1 (expected) for M H = 160 GeV

Combines sixteen mutually exclusive final states for WH, ZH, WW 7.7  SM at m H =115 GeV 1.4  SM at m H =160 GeV 4.2  SM at m H =115 GeV 2.5  SM at m H =160 GeV observed expected

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

 b (b)  bb b(b) Search g g b b  0 b g b At high tan  Br(H/A  bb)  90%, but swamped by QCD background Look for associated production with b s. 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 0.90 fb -1 (m A =120 GeV)

0.90 fb fb -1  b (b)  bb b(b) Search CDF found two useful discriminators m 12 (invariant mass, 2 leading jets) m diff = mass of the tracks assigned to jet from the displaced vertex

Neutral MSSM Higgs   had Main backgrounds: Z  (irreducible), W+jets, Z  ee, , multijet, di-boson DØ:  -channel analysis completed CDF: e, , e +  channels 1 isolated  separated from opposite sign hadronic  isolated e or  separated from opposite sign hadronic  set of 3 NNs discri- minate  from jets variable-size cone algorithm for  m vis < 20 GeV removes remaining W background > 55 GeV W s 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 Both experiments in good agreement with the SM

Neutral MSSM Higgs   had Both experiments give similar results: in the 90<m A <200 GeV region tan  > ~40-60 excluded for the no-mixing and m h max benchmarks

is accessible to the Tevatron provided m H  is not too large! Background rates in 3  final state are very low measured fake rates for Z  or W  tri-photon production extrapolated from di-photon sample For tan  > 1, m H  < 200 GeV and m h < 90 GeV B( h   )  1 and B( H   hW  )  1 Fermiophobic Higgs Decaying to 3  A production mechanism unique to hadron colliders No obvious structure in diphoton mass spectrum m  GeV/c 2 p T GeV/c

Optimizing final selection on 3  s E T > 30, 20, 25 GeV and  p T > 25 GeV rejects background ProcessEvents expected direct 3  0.9  0.2 estimated 3  fakes0.3  0.05 Observed0 LEP2 limits of 108 GeV/c 2 assumed SM coupling h f V V Fermiophobic Higgs Decaying to 3 

Fermiophobic Higgs in 2  + X 1.1 fb -1 Selection: 2 photons (p T > 25 GeV) m h >92 GeV at 95% CL Background: ,  +jet and jet+jet Signal region: q T  > 35 GeV bkgd  1 

~ ~ ~ ~ ~ Particle Name Symbol Spartner Name Symbol gluon g gluino g charged Higgs H + chargino  1,2,3,4 charged weak boson light Higgs h neutralino  1,2 heavy Higgs H pseudoscalar Higgs A neutral weak boson Z photon  quark q squark q R,L lepton l slepton l R,L SUPERSYMMETRY 0  The L ightest S upersymmetric P article provides E T if the LSP is stable, neutral, colorless & R-parity is conserved photons and E T if the LSP is a gravitino and NLSP a neutralino long-lived particles if the LSP decays weakly 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 SU(1) M 2 SU(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 different class of models MSSM Assumptions: SUSY particles are pair produced Lightest SUSY particle (LSP) is stable Lightest SUSY particle is 5 free parameters m o common scalar mass m 1/2 common squark mass A o trilinear coupling tan sign( SUSY Symmetry Breaking mSUGRA

with  0 as L ightest S upersymmetric P article and Search for: 2 acoplanar jets plus E T >60 GeV Stop  charm + E T R-parity pair production veto on Leptons, isolated tracks and and flavor tag (>= 1 jet) ~

Stop  charm + E T Finally optimize mass-dependent cuts on H T and P =  max +  min For H T >140 GeV P<320 GeV CDF has submitted results with 295 pb -1 not appearing on this plot Total SM BKG  3.22 Data66

Search for Long-lived Stop Tracking Chamber Electromagnetic Calorimeter (EM) Muon Detector CDF Hadronic Calorimeter TOF A long-lived, charged massive particle (CHAMP) appears as a “slow” muon. 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) – High P T, low velocity, highly ionizing “muon” – Measure velocity (  ) via TOF detector + timing from tracking detector – Calculate mass from momentum and  Data Control Region dominated by W  Signal Region MC signal

Search for Long-lived Stop Exclude stable stop with m<250 GeV/c 2 at 95%CL Signal region: no candidates with m >120 GeV/c 2 consistent with expected background Prospino2

Squarks/Gluinos  jets + E T Assuming R-parity is conserved, squarks and gluinos can decay directly into the LSP (  0 1 ). or cascade down to the LSP The dominant signature for pp  qq, qg, gg + X is jets+ E T    At least 3 jets E T > 25 GeV and E T > 25 GeV Separate 2-jet, 3-jet and >3-jet analysis.

Squarks/Gluinos  jets + E T Mgluino < 290 GeV/c 2 for any M q Mgluino < 380 GeV/c 2 excluded for M g ~ M q 1.4 fb -1 A 0 =0 tan  = 5  <0 ~ ~

Squarks/Gluinos  jets + E T Mgluino < 402 GeV/c 2 excluded for Mg~Mq Mgluino < 309 GeV/c 2 excluded – any Mq ~ ~ 0.96 fb -1 A 0 =0 tan  = 3  <0

Squarks   had + jets + E T τ -τ - A 0 =  2m 0 tan  = 15  < 0 enhanced  decay Selection: 2 or more jets E T > 35 GeV E T > 75 GeV at least one hadronic  Optimization: E T > 175 GeV > 325 GeV

Squarks   had + jets + E T Predicted Yields Signal (m 0,m ½ ) ( 80,160)4.7  0.4 (100,150)7.1  0.6 Background 1.7 Data 2 LEP2 slepton searches LEP2 chargino searches Translating to

Chargino/Neutralino  Trileptons Production of   1  0 2 will lead to trilepton final states with E T 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 interpreted within select mSUGRA scenarios ~ ~ Large  and Br  Maximal 3 ~~ still presents the challenges of low p T leptons

Chargino/Neutralino  Trileptons DØ ee +track: Final Selection Signal: 1-2 events Background: 1  0.3 Data: 0 DØ Combined Limit (5 analysis) : CDF Combined Limit (14 analysis) :

Conclusions With 2 fb-1 of data, and many channels analyzed, the Tevatron is rapidly approaching the sensitivity of expected SM Higgs signals. With a final data set expected to be 6-7 fb -1 per experiment you can look forward to exciting results (2009). Meanwhile : There is also no evidence yet for any MSSM Higgs. Broad searches continue for the signatures of Supersymmetric decays (from squarks, gluinos, charginos, neutralinos & sleptons), but to date, none have been observed. New limits have been set on SUSY masses and mSUGRA parameters.