LHC Prospects on Higgs and physics beyond the Standard Model (SUSY) Riccardo Ranieri INFN and Università degli Studi di Firenze on behalf of ATLAS and CMS Collaborations DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba (Japan), April 2006

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 2 ATLAS & CMS at LHC –Detectors optimised for Higgs boson and SUSY searches LHCpp √s=14 TeV  very high energy: LHC pp √s=14 TeV σ pp =55 mb –inelastic cross section: σ pp =55 mb 40 MHz –interaction rate: 40 MHz (2x)10 33 cm -2 s -1  cm -2 s -1  high luminosity: (2x)10 33 cm -2 s -1  cm -2 s fb -1  100 fb -1 –per year: 20 fb -1  100 fb -1  BIG detectors –CMS: 15 m x 21.5 m –ATLAS: 25 mx 46 m CMS = Compact Muon Solenoid LHC = Large Hadron Collider ATLAS = A Toroidal LHC ApparatuS first collisions in Autumn 2007

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 3LHC

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 4ATLAS

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 5CMS

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 6 Expected LHC schedule 1 st July 2007 LHC closed and set up for beams August 2007 first beam in machine October / November 2007 first collision followed by a short pilot run (~10 pb –1 ) someday in 2008 first physics run (few fb –1 ) from 2009 physics run 10/20 fb –1 to 100 fb –1 per year TeV4LHC, April commissioning/presentations/lamont- comm-tev4lhc.ppt

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 7 Where will we be at LHC startup? m H >114.4 GeV/c 95% CL m H =115 GeV/c 2 ¿ Higgs boson signal m H =115 GeV/c 2 from LEP2 data ? CERN-EP/ LHWG Note/ Searches at TeVatron up to LHC startup…  year 2007: ~2 fb -1  m H <125 GeV/c 2 covered to exclusion year 2008: ~4 fb -1 year 2008: ~4 fb -1  m H <130 GeV/c 2 covered to exclusion  3σ evidence up to m H =125 GeV/c 2 FERMILAB-PUB-03/320-E

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 8  Associated production ttH and bbH –high-p T lepton, top reconstruction,b-tag-- SM Higgs Production at LHC  Gluon Fusion –the highest cross section  Vector Boson Fusion –two high-p T forward jets  Associated Production WH and ZH –one or two high-p T leptons useful for the trigger

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 9 SM Higgs Decays “light” Higgs 2m Z –decays into Vector bosons W and Z »“golden” channels –two-photon decays »extremely “clean” but rare and difficult to detect LEP excluded –hadronic and  decays are favourite »…but difficult to select

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 10 Low Mass Higgs: H →  This decay is very rare (Br≈10 -3 )  σ(pp → H 115 )xBr(H →  )=76 fb (NLO) S/B≈1/20 mass peak –good  resolution  mass peak crucial σ(m  )/m  ≈1% –Electromagnetic Calorimetres crucial for H →  : σ(m  )/m  ≈1% needed  motivation for LAr (ATLAS) and PbWO 4 (CMS) calorimetres –high granularity –response uniformity CERN/LHCC ATLAS TDR 1 CERN/LHCC ATLAS TDR 2 CERN/LHCC CMS TDR 4 –3 main background processes: 81 pb »irreducibile: gg/qq →  81 pb 9x10 4 pb »  +jet (with “real” or “fake” second photon)9x10 4 pb 10 8 pb »hadronic QCD jets (π 0 decays) 10 8 pb 10 fb -1 m H =115 GeV/c 2 »ATLAS reach with 10 fb -1 and m H =115 GeV/c 2 : S/√B=2.0 »Signal Significance: S/√B=2.0 (K-factors not included)

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 11 Low Mass Higgs: ttH( → bb) This is the favourite decay  σ(pp → H 115 )xBr(H → bb)=28 pb S/B<10 -7  tagging the top quarks helps a lot 1.t → bW( → μν ) 2.t → bW( → jj)  “crowded” final state –6 jets (4 of them are b-jets) + additional ISR/FSR jets »4 b-tagged jets needed to reduce combinatorics –1 isolated lepton »it’s the key for trigger  optimised analysis –p z from W-mass constraints –likelihood pairing of jets -- - ATL-PHYS ν »Final result for likelihood analysis (m H =115 GeV/c 2 ): »30 fb -1 : S/√B=3.4 »10 fb -1 : S/√B=2.0

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 12 ∫ L =30 fb -1 ℓ ν +jet ℓ ν +jet full simulation Jet Vector Boson Fusion: qqH( →  )  hadronic jets in forward-backward regions –the forward jet tagging is a powerful background rejection tool low η  hadronic activity suppressed in low η region –emitted vector bosons are colour-singlets  → ℓ ν ℓ’ ν ’, ℓ ν +jet  Search for  → ℓ ν ℓ’ ν ’, ℓ ν +jet final states –S/√B≥5m H =120÷140 GeV/c 2 40 fb -1 –S/√B≥5 in m H =120÷140 GeV/c 2 range with 40 fb -1 »S/√B≈2.5 in one LHC year »this process offers the possibility for a direct measurement of Yukawa coupling H  Phys. Rev. D59 (1999) ATL-PHYS CMS AN Jet   Higgs Decay products Forward tagging jets [VBF]

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 13 Light Higgs Summary Detector/performance requirements: HHHH→response uniformity of electromagnetic calorimeter HHHH→bbb-tagging capability of tracking system qqqqqH(→)efficient j jj jet reconstruction in 3<|η|<5 aaaallgood u uu understanding (<10%) of the b bb background Three complementary channels 2σ Each channel contributes with ~2σ to the total significance Observation of all channels is very important to extract a convincing signal in the first year(s) -

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 14 High Mass Higgs: H → WW (*) VBF qqH → qqWW –Di-lepton final state  WW → ℓ ν ℓ ν ( ℓ =e,μ)  b-jet and  veto in the central region to reject tt background  Drell-Yan background ee, μμ discarded with lepton cuts: –M ℓℓ 30 GeV/c –Main decay channel around m H =170 GeV/c 2 Isolated leptons WW (*) → ℓ ν ℓ ν ( ℓ =e,μ) Missing transverse energy E T miss Dangerous background from top decays –central jet veto WW spin correlations for the signal –small ℓ + ℓ - opening angles CMS NOTE 2006/047 ATL-PHYS fb -1 are more than enough if m H is around 170 GeV/c 2 -

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 15 golden –The “golden” channel Z → μ + μ -  well defined peaks Z → μ + μ - –m H >2m Z –m H >2m Z : real Z’s  main backgrounds –reducible: tt, Zbb »μ isolation »Z reconstruction (m Z ) –irreducible: ZZ »qq production mechanism dominates  softer muons 5σ  Luminosity required for a 5σ discovery: –10-30 fb -1 if m H >2m Z »2-3 low luminosity LHC years –up to 100 fb -1 if m H <2m Z »only one reconstructed Z »high luminosity runs High mass Higgs: H → ZZ (*) → 4μ CMS AN CMS AN

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 16 ATLAS & CMS Discovery Potential  After detector calibration and LHC pilot run… first year –…almost all the “allowed” mass range can be explored during the first year (10 fb -1 ) 2 years 7 σ more than one –...after 2 years (≈30 fb -1 ) 7 σ significance over the whole mass spectrum, covered by more than one channel »LEP excess is near… CMS NOTE 2003/033CERN/LHCC ATLAS TDR 15

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 17 4 neutral fermions: Neutralinos:  1,2.3,4 ~0 ~0 ~0 ~0 4 charged fermions: Charginos:  1,2 ~± ~± ~± ~± MSSM - mSUGRA 5 Higgs bosons: 2 neutral CP-even: h, H 1 neutral CP-odd: A 2 charged: H +,H - 5 Higgs bosons: 2 neutral CP-even: h, H 1 neutral CP-odd: A 2 charged: H +,H - mSUGRA 5 parameters: m ½, m 0, tanβ, A 0, sign(μ)

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 18 MSSM Higgs boson masses –Born level  m h <m Z  m A <m H  m W <m H ±  m A m H ± m W  m A =(m H ±2 -m W 2 ) ½ –Loop corrections  depend on top and stop masses, mixing, … h  modify previous sequence, important for h Phys.Rev. D66 :055004,2002 hep-ph/ Higgs Mass [GeV/c 2 ] m h increases with m A up to asymptote: m h <130 GeV/c 2 m H, m A and m H ± degenerate for m A >140 GeV/c 2 m A /m Z >>1MSSM hSMHiggs when m A /m Z >>1 MSSM h behaves as a SM Higgs

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 19 Neutral MSSM Higgs at LHC –Production: »gg → A/H »pp → A/Hbb –Neutral Higgs mixing ( α ) modifies couplings to bosons and fermions with respect to the Standard Model –high tan β »enhanced decays h/H/A → bb, ττ –low mixing α »h → bb, ττ suppressed - - -

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 20 –A lot of decay channels –“SM like” »h → ,bb »H → 4ℓ –purely MSSM »A/H →μμ, ττ,bb »H → hh »A → Zh »H ± →τν,tb –if decay into SUSY sparticles are allowed »H/A →  2  2 »  2 → h  1 –Complete coverage 30 fb -1 –Complete coverage of (m A,tan β ) plane with 30 fb -1 »high tan β -m A region is the more accessible »only h detectable in most of the plane H and A searches - - ~ 0 hep-ex/ (LHWG Note ) 95% CL Limits m t =174.3 GeV/c 2 m h [GeV/c 2 ] m A [GeV/c 2 ] tanβ No mixing (2005) > ÷10.2 m h max (2005) >92.8> ÷2.0

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 21 h/H/A → μ + μ -  Enhancement of BR(h/A/H → μ + μ - ) for high tan β –Main backgrounds: »Drell-Yan Z/  * → μ + μ - »tt (both t → bW → bμ ν μ ), Zbb –Background suppression »b-tagging (suppresses DY) »central jet veto (reduces tt, Zbb) »E T miss cut (reduces tt)  Three regions (m h max <135 GeV/c 2 ): m A >>m h max 1.Decoupling regime m A >>m h max »h similar to SM, A/H indistinguishable m A <m h max 2.Low m A regime m A <m h max »H similar to SM, h/A degenerate »Z peak, high luminosity needed m A ≈m h max 3.Intense coupling regime m A ≈m h max »h/H/A not degenerate in mass »indistinguishable (detector resolution) σ5σ5σ5σ without systematic uncertainties CMS AN

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 22 h/H/A → μ + μ - and tanβ –Proportionality between tan 2 β and Higgs boson width Γ A –Full reconstruction of Higgs boson state  measurement of tanβ  possible only in 150<m A [GeV/c 2 ]<200 region  Correction to Γ A –subtraction of di- muon invariant mass resolution »Voigt function –not perfect degeneration H/A »measured effective width is not the intrinsic one CMS AN

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 23 MSSM Charged Higgs  H ± production t → H ± b –if m H ± <m t : t → H ± b gb → tH ± –if m H ± >m t : gb → tH ±  Decays: H ± →τν –if m H ± <m t : H ± →τν H ± → tb –if m H ± >m t : H ± → tb  LEP 95% CL limit: –m H ± >78.6 GeV/c 2 »decay channels: H ± →τν,cs LHWG Note hep-ex/

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 24 H ± searches  m H ± <m t –search in tt events »lepton from top quark »τ from H ± →τν τ –excess of τ ’s in tt events »H ± mass can not be reconstructed  m H ± >m t –associated production with top »gb → tH ± ( →τν τ,tb) –background from tt and Wt »final states with τ leptons CMS NOTE 2000/039 CMS NOTE 2000/045 CMS NOTE 2002/024 CMS AN CMS AN

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 25 SUSY LHC discovery reach  1 fb -1 of data should allow discovery if squark or gluino mass < 1.5 TeV/c 2.  ATLAS and CMS potentials similar perfectly known SM physics  Those studies assumed a perfectly known SM physics (only statistical errors on background rate) and ideal detectors (perfectly aligned, nominal asymptotic performance)  SUSY discovery likely to depend not on statistics but on the understanding of SM background and detector systematics: excess of events 1 fb -1 q (1 TeV/c 2 ) ~ g (1 TeV/c 2 ) ~

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 26 Sleptons discovery reach

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 27 It is not enough to observe the excess over the Standard Model… Fix a set of points in the parameter space Get information on the spectrum (end-points) Reconstruct sparticles DISCOVERY SUSY SPECTROSCOPY This requires a different approach…

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 28 ∫ L =30 fb -1 tanβ=2.1 m 0 =100 GeV/c 2 m ½ =300 GeV/c 2 A 0 =-300 GeV sign(μ)=+ M ll (GeV/c 2 ) Edge accuracy with 30 fb -1 : 0.5% e + e - +  +  - The golden decay  The neutralino leptonic decay is the starting point for reconstruction of the sparticle masses l q q l g ~ q ~ l ~  ~  ~ p p ∫ L =5 fb -1 tanβ=6.0 CERN/LHCC ATLAS TDR 14 CERN/LHCC ATLAS TDR 15 hep-ph/ E T miss key point The measurement of the missing transverse energy E T miss is the key point

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 29 Sparticle reconstruction –Lepton scale: »LHC goal: 0.1% »material budget, alignment, magnetic field –Jet energy scale: »LHC goal: 1% »FSR, jet cone –Reconstruction can be done with only 1-10 fb -1 –Statistical uncertainties <<1% with 300 fb -1 –Main uncertainty: energy scale and LSP mass p p b b 300 fb -1

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 30 The earliest discovery?  A new resonance decays into two leptons… Z′ (new gauge boson) ? A H, Z H (Little Higgs) ? G (1) (Randall-Sundrum) ?  (1) /Z (1) (TeV -1 Extra Dimensions) ? G (KK) (ADD) ? … ?

DIS2006 Tsukuba, April 2006 LHC Prospects on Higgs and BSM Physics Riccardo Ranieri 31Conclusion –L–LHC has potential for Higgs boson(s) and SUSY particles discovery a aa already in the first year (months?) of operation 11 LHC day at cm -2 s -1 ≡ 10 years at previous machines BUT –A–At the beginning a aa a lot of time (whole first year?) will be needed to understand the detectors, reach the desired performance, optimize physics selection and precisely measure SM backgrounds HOWEVER –T–The A AA ATLAS and C CC CMS detectors are d dd designedfor new physics searches, n nn no surprise that they can cover most of the spectrum of H HH Higgs and sparticle masses within year of start of physics collisions