ICHEP 04 Barr Higgs

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Information about ICHEP 04 Barr Higgs

Published on June 19, 2007

Author: Mahugani

Source: authorstream.com

Higgs and SUSY at the LHC:  Higgs and SUSY at the LHC Alan Barr on behalf of the ATLAS and CMS collaborations ICHEP-17 Aug 2004, Beijing Outline:  SUSY and Higgs discovery reviewed Reach, channels Focus on some recent work: Determination of higgs v.e.v. ratio (tan b) SUSY spin measurement Mixed Higgs + SUSY cascade decays Discovery and measurement of: Higgs sector of MSSM SUSY partners of SM particles Outline (S)particle reminder:  (S)particle reminder SM+ MSSM Higgs SUSY quarks (Landamp;R) leptons (Landamp;R) neutrinos (Landamp;?) squarks (Landamp;R) sleptons (Landamp;R) sneutrinos (Landamp;?)  Z0 W± gluon B W0 h0 H0 A0 H± H0 H± 4 x neutralino 2 x chargino After Mixing gluino Spin-1/2 Spin-1 Spin-0 Spin-1/2 Spin-0 Bino Wino0 Wino± gluino ~ ~ Extended higgs sector (2 doublets) Neutral Higgs production:  Neutral Higgs production Mass of H or h Slide5:  fb-1 1 year @1033 1 month @1033 1 year @1034 SM-like higgs discovery ATLAS Values for single experiment h → tt requires excellent low-pT lepton + tau jet trigger time h: Number of observable final states :  h: Number of observable final states 1 channel 2 channels 3 channels 4 channels 5 channels several channels observable allows parameter determination ? 300 fb-1 Excluded by LEP Suppressed b, t Suppressed g coupling Conservative in tan b Heavy neutral higgs (H,A):  Heavy neutral higgs (H,A) Measuring tan b (1):  Measuring tan b (1) For large (andgt;5) tan b b Yukawa dominates s s  tan2 b Measure s Compare to NLO Ratio of v.e.v.s of the 2 MSSM Higgs doublets Important for understanding EWSB ~ Measuring tan b (2):  Errors dominated by theoretical uncertainty on NLO cross-section With signal discovery at 5σ, tan b measurable to 35%. Measuring tan b (2) N.B. m, M2 kept fixed here Charged higgs production/decay:  Charged higgs production/decay Associated production with t and b quarks Decay H± → Very complicated final state! Combinatorial BG Also H± → t nt BR decreases as mA increases ~6 jet + lepton + missing energy SM background uncertain? Charged higgs:  When H+ is close to top mass: H+ -andgt; tb or t -andgt; H+b Revised analyses in progress ATLAS Charged higgs Overall Discovery Potential: 300 fb-1:  Overall Discovery Potential: 300 fb-1 Can we distinguish between SM and extended Higgs sectors by parameter measurements? ATLAS Whole plane covered for at least one Higgs Large wedge area (intermediate tan b) where only h is observed No direct evidence for higgs beyond SM SM or Extended Higgs Sectors?:  SM or Extended Higgs Sectors? First look using rate measurements from VBF channels (30fb-1) R = BR(htt) BR(hWW) D=|RMSSM-RSM|/sexp only statistical errors considered assumes Higgs mass exactly known Deviation from SM expectation potential for discrimination seems promising! ATLAS Searching for SUSY:  Searching for SUSY If SUSY was exact we’d have seen it already Variety of ways to induce SUSY masses: Minimal super-gravity (mSUGRA) Anomaly mediated SUSY breaking (AMSB) Gauge mediated SUSY breaking (GMSB) Experimental emphasis is on building general toolkit of techniques based on types of signatures of above Generally search reach ~2 TeV. SUSY Discovery - mSUGRA:  Finial discovery limit ~ 2.5 TeV squark or gluino Initially will be limited by detector uncertainties, not SUSY stats! Also need to understand SM backgrounds SUSY Discovery - mSUGRA Scalar mass term Gaugino mass term Slide16:  Slepton, squark, neutralino masses Apply corrections for electron and muon energy scale and efficiency Flavor Subtracted mass to remove the contribution from uncorrelated SUSY decays: e+e- + m+m- - e+m- - e-m+ M(c2)-M(c1) ≈ 105 GeV 5 fb-1 SUSY measurements - mass:  SUSY measurements - mass Mass measurements from exclusive cascade decays Mass differences well measured Typically limited by detector performance Of order 1% Error in overall mass scale Unknown missing energy Of order 10% c01 q q c01 p p SUSY SPIN @ LHC:  SUSY SPIN @ LHC SUSY particles have spin differing by ½ from SM 'Discovering SUSY' means measuring spins of new particles Possible at LHC? Investigation of mSUGRA 'Point 5' Spin-½, mostly wino Spin-0 Spin-½ Spin-0 Spin-½, mostly bino Final state = jet + l+ + l- + ET ( + decay of other sparticle) Polarise Measure Angle (or inv mass) Chiral coupling Similar technique allows measurement of tanb from muon/electron asymmetry SUSY spin – observable distributions:  l+ l- parton-level -andgt; Measure spin-1/2 nature of neutralino-2 -andgt; Also can measure scalar nature of slepton -andgt; Success at several distinct points in parameter space detector-level Lepton+jet invariant mass Charge asymmetry, spin-0 Events SUSY spin – observable distributions ATLAS ATLAS SUSY produces Higgs:  SUSY produces Higgs g (600 GeV) ~ q (720 GeV) ~ ~ ~ ~ ~ h0, H0, A0, H± (170 GeV) (95 GeV) ~ (340 GeV) ~ Provided Heavy higgs are andlt;150 GeV -andgt; produced Missing energy + jet/lepton + higgs decay-andgt;bb Apply very simple (general) analysis Strongly interacting, so high rate g (1200 GeV) ~ q (800 GeV) ~ ~ ~ (400 GeV) (200 GeV) ~ h0, H0, A0, H± ~ ~ (1000 GeV) ~ Other points andamp; combinations also investigated ~ SUSY -> h,H,A -> bb:  SUSY -andgt; h,H,A -andgt; bb : susy signal : susy bkg : SM tt bkg H0, A0 -> SUSY -> leptons:  H0, A0 -andgt; SUSY -andgt; leptons hep-ph/0303095 SUSY -> light higgs:  SUSY -andgt; light higgs Region of parameter space where h is discoverable ~ cosmological 'bulk region' CMS note 2003-033 for summary H± -> SUSY :  H± -andgt; SUSY Harder! Works in restricted area of m, M2 space Complements tau, tb analysis. hep-ph/0303093 H  2,30 1,2  3l + ETmiss Conclusions (1):  Conclusions (1) LHC SUSY and Higgs search strategies well developed Constantly being reviewed / developed New techniques in Higgs sector Production via Vector Boson Fusion Improves reach for MSSM benchmarks Couplings if only lightest higgs accessible Infer non-SM Higgs sector Measurement of tan b Conclusions (2):  Conclusions (2) New SUSY techniques Lepton asymmetry Charge -andgt; spin determination Flavour -andgt; tan b Full likelihood event reconstruction 3rd generation squarks + heavy gauginos (not covered in this talk) Combined SUSY + Higgs Complimentary to standard Higgs searches Could help dis-entangle complex SUSY chains Much work going on for trigger, calibration, systematics. Backup slides:  Backup slides SM-like higgs discovery:  ATLAS SM-like higgs discovery h → tt requires multi-object t-jet, lepton trigger Charged higgs:  Charged higgs SUSY spin – lepton asymmetry:  SUSY spin – lepton asymmetry m/mmax = sin ½θ* Back to back in 20 frame θ* quark lepton Phase space -andgt; factor of sin ½θ* Spin projection factor in |M|2: l+q -andgt; sin2 ½θ* l-q -andgt; cos2 ½θ* l+ l- Phase space Probability Invariant mass In presence of spin- correlations, lq invariant mass is different for l+ and l- mSUGRA Dilepton edge reach:  mSUGRA Dilepton edge reach SM-like higgs rate measurement:  SM-like higgs rate measurement Slide33:  Overall Summary Two experiments, 30 fb-1, charged and neutral higgs.

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