S. Bolognesi (1) from CMS A. Di Simone (2) from ATLAS 1 Università di Torino ed INFN Torino 2 Università di Roma Tor Vergata ed INFN Roma 2 V workshop

S. Bolognesi(1) from CMS

A. Di Simone(2) from ATLAS

1 Università di Torino ed INFN Torino2 Università di Roma Tor Vergata ed INFN Roma 2

V workshop italiano sulla fisica p-p ad LHC

Perugia, 30 Gennaio - 2 Febbraio, 2008

Higgs @ Higgs @ LHCLHC

• Higgs at TevatronHiggs at Tevatron• Higgs in ItalyHiggs in Italy• Low mass searchesLow mass searches

– ttbbttbb– H → H → – H → H →

• H → VV channelsH → VV channels– H H →→ ZZ(*) ZZ(*) → → 4l4l– HH→→WWWW→→llll

• MSSM HiggsMSSM Higgs• Combined resultsCombined results

• Discussion

Outline

2Sara Bolognesi - CMS Torino V workshop italiano su LHC - Perugia

Higgs @ Tevatron pessimistic scenario → 5.83 fb-1

(same performance of 2007)realistic scenario → 6.75 fb-1

Projected Integrated Luminosity in Run II

Inte

gra

ted

lu

min

os

ity

[fb

-1]

0

1

2

3

4

5

6

7

01/03 01/04 02/05 03/06 02/07 04/07 04/08 05/09

• Collected >3 fb-1, expected 6 or 7 fb-1 by the end of 2009

• With 1.9 fb-1 analysis close to exclude wide range MH ≈ 160 GeV• Sensitivity lower than expected in low MH region

analyzed data

expected 2009

Exclusion Limit: Tevatron Run II Preliminary


Higgs in Italy!!

ttH → ttbb

H→

H→

H→ZZ

H→WW

higgs MSSM and BSM

old analysis from Pavia; Perugia, Napoli

Roma not yet started

SM Pavia, Pisa;

Milano, Roma Torino, Bari, (e.o.i Bologna, Padova, Trieste)

Padova, Roma, Milano (e.o.i Bologna, Trieste)

Milano, Bologna, Perugia, Pisa

Genova

Milano

SM Pisa,

CMS ATLAS

Roma1, Roma2, LNFGenova, Cosenza, Pavia

Roma1 in the next future

MSSM: Roma1, Milano

LNF, Roma1


MSSM Pisa

Low-mass searches Low Higgs mass favoured by EW precision measurements

Most difficult mass region:

with mH<130 GeV the most promising decay channels are into photons and taus ( ≈ 50 and 100 fb)

• very high background rate (also from fakes)

• VBF production channel gives the best s/b ratio

• in MSSM the di-photon decay channel is suppressedanalyses focus on di-tau final state

at low mass BR(H→bb) ≈ 70% but it cannot be a low lumi discovery channel:

associated production ttH ( × BR ≈ 0.3 pb)• very complex final state, many systematics involved

• huge QCD background


E.Gabrielli, F.Maltoni, B.Mele, M.Moretti, F.Piccinini and R.Pittau,“Higgs boson production in association with a photon in vector boson fusion at the LHC,'‘ Nucl. Phys.781 (2007) 64 [arXiv:hep-ph/0702119]

• NEW IDEA: VBF Higgs with H→bb + request of a high pT central photonpioneer parton level study shows s/b increases of more then one order of magnitude (destructive interference in central emission in QCD bbjj):

ttH → ttbb (MH ≈ 120 GeV) Complex final state (2W,4b)

combinatorial background

good detector control (b-tag, jet reco/calib,…)

• full simulation• control samples (align, jet calib)

CMS: S/√B <0.1 with 60 fb-1 (NO discovery channel) [≈ 3 without syst.]

• low trigger efficiency WW→ll WW→ljj

77% 63/52%more sophisticated trigger needed

• b-tag performance at best for pTjet ≈ 80 GeV (while ttbb contains many low pT jets)

• jet reco/calib. performance still poor energy flow / jets with tracks needed (they would improve also b-tag)

Big QCD background (ttjj, ttbb)

dedicated study on background normalization and shape from data

multivariate technique


WW→jjjj

25%

ATLAS preliminary(after likelihood analysis)

• … but better jet resolution:

ATLAS: S/√B ≈ 2.3 with 30 fb-1 (only semilept., NO systematics included)

• slightly worse efficiencyVSfake leptons performance …

• … similar btag performance …M(t→bjj)

ATLAS

CMSCMS


m≈16 GeV if soft muons added to b-jet

M(H→bb)

ATLAS

mjjb=174GeV

m = 11.7 GeV

mbb=98GeV

m = 20.0 GeV

H → (MH ≈ 130 GeV) Vertex reco is crucial for correct mass measurement

CMS: vertex fitted from high-pT tracksresolution 5mm (low lumi)

ATLAS: calorimeter transverse granularity ≈ 1.6cm

vertex from other tracks can be added too ≈ 40m

CMS

/0 and /jet discrimination needed to suppress huge reducible background (j ≈ 103 , jj ≈ 106)

using hadronic leakage and shower shapes, exploiting calorimeter granularity(total rejection of ~3000 for efficiency of 80%)

ATLAS:

isolation against jets CMS:0 rejection with Neural Network with input variables related to shower shape + silicon preshover info in the EndCaps

8Andrea Di Simone - ATLAS Roma V workshop italiano su LHC - Perugia

exploited

H → (2) Photon conversions are important, due to material

balance in inner detectors ATLAS: ~30% s convert in the barrel CMS: 42% in the barrel, 59.5% in the endcap

Trigger based on detections of high-energy isolated photons ATLAS: 220i, 60, 2d20i||60 CMS: efficiency (212i) is 89.2% at L1 and 87.4% at HLT.

• no veto on tracks → high trigger also for di-electron events

Associated production allows to improve s/b ratio. Both ATLAS and CMS are studying several channels

“Advanced” analyses (NN, Likelihood, categories) allow to improve results with low statistics

CMS NN

Significances@30fb-1:ATLAS: 6.3 cut based

CMS: 6.0 cut based, 8.2 NN

9 V workshop italiano su LHC - PerugiaAndrea Di Simone - ATLAS Roma

7.7 fb-1

signal × 10

H → (MH ≈ 130 GeV)

ATLAS performing studies on all final states (ll, lh, hh), while CMS focused in the recent past on lh decay channel.

Both experiments are focusing on VBF production channel, since it allows to improve s/b ratio.

Main background:

irreducible Zjj (QCD), help by CJV irredicible Zjj (EW) help by mass reconstruction reducible: QCD multi jet, W+jet, Z/+jet, tt

Trigger:

ATLAS: e25i and mu20i for lh or ll final states. More complex trigger schemas (tau+mu or tau+e) are also under study. Single tau trigger exposes to huge QCD background, so for hh final state tau+MET seems the most promising trigger choice

single e || single mu || e+tau || mu+tau at L1 and HLT CMS:


H → (2) Forward jet tagging: identifying the quark-initiated jets

from VBF: typically in opposite hemispheres and high-pT

CMS: selects the two highest Pt jets and requests opposite sign

ATLAS: like CMS or choose the highest pT one and couple it with the highest found in the opposite hemisphere

ATLAS

challenge is to make it robust against additional pileup/fake jets

Significances at 30 fb-1

ATLAS:•lh MH=130 GeV , Sign. 4.4

•lh + ll MH=130 GeV Sign.

5.7 CMS: lh MH=135 GeV , Sign. 3.98

CMS

Central jet veto: no additional hard jets


Central jet veto

H→VV channels


For MH>130 GeV, H→VV most promising channels:effectiveness of ZZ and WW channels follows closely the BR shape

• mH 150 high ZZ BR and low backgrounds

• mH 170 low ZZ BR while H→WW turns on

• mH 200 strong enhancement of ZZ BR for mH > 2mZ (suppression of WW)

• mH > 350 lower signal xsec and BR (due to H→tt)

VBF VV→VV interesting ‘per se’ as a probe of EWSB mechanism:

Higgs in s-channel → mass peak no Higgs → SM unitarity violation

H → ZZ(*) → 4l channels Interesting over a wide mass range, mainly for their very clean signature:

most critical mass region is 125-150 GeV, where one Z is off-shell, leading to low pT leptons

Backgrounds:

ZZ*/*→ 4leptons: irreducible background, cross section ~ tens of fb→ the biggest one after analysis selection Zbb: reducible (lepton isolation and impact parameter), cross section ~hundreds of pb, rejection factor ~O(103) needed:

tt: reducible, rejection factor ~O(105) needed

Reduce PDF, luminosity and background uncertainties normalizing from sidebands or using ZZ → 4l) / Z → 2l)

Lepton identification and reconstruction are crucial for selection efficiency and H mass reconstruction:

lepton performance measured from Z → 2l


(big uncertainty on gg→ZZ)

H → ZZ(*) → 4l (2) Trigger: inclusive single mu/e, double mu, double e, have good signal efficiency and bg rejection

Main systematics come from lepton energy scale/resolution and lepton-id efficiency

results from single Z→ll (e.g. tag and probe) crucial for systematics control

ATLAS mu reco

CMS e reco


CMS

ATLAS

Preliminary

H→WW→ll (MH≈130-180 GeV)

to be carefully monitored: bkgr normalization from real data

systematic effects on background shape and normalization

No mass peak: alternative variable ll)

extrapolation from control regions (ad hoc for tt and WW)

ATLAS documented work mainly about:

MC physics model description:

dedicated MC for gg→WW

interference between single top (produced in association with b) and double top

Ex:

5.3% uncertainty on WW normalization (theoretical systematic dominates)12.2% uncertainty on tt normalization (theor. syst. and jet energy scale)

(10% of qq→WW after cuts and different shape)

detailed background normalization procedure and evaluation of theoretical uncertainties:

MC@NLO for signal and most backgr.

but pT(WW) modeled by PS (no NLO available)


preliminaryATLAS

CMS more focused on:

simulation of real detector and real data workflow (trigger, skimming)

detector performance measurement from data:

electron identification efficiency extrapolated from Z→ee (tag & probe)

lepton fake rate measured from QCD multi-jets events to evaluate the W+jets impact

from MC from “data”

different pT, spectra

(different jet flavour decomposition under study)

MET systematics• from W mass measurement → 5% on resol, 2% on scale• comparison of W and Z with one lepton removed

H → WW → ll: experimental systematics (e,MET)


CMS

MSSM Higgs discovery potential

Light neutral h (same analysis of SM):

particularly effective VBF with h→complemented by VBF/ggF with H→VV in the small scenario (low H- coupling)

Heavier neutral A/H:

• high tg: bbH with h→ (, low BR but clean)

• low tg: GGF with A → Zh → llbbA/H → 0

202 → 4l + MET

Charged H±:

• mH<mt: tt→tHb with H→

gg→tbH gb→tH

withH→ (lower BR but cleaner)

H→tb• mH>mt:

high background (QCD, tt, tt+(b)jets, W+(b)jets) also combinatorial

At intermediate tg, sensitivity only to h also with 300 fb-1 → difficult to disentangle MSSM and SM


MSSM study for low lumi

ATLAS: bbh → bb with Mh ≈ MZ

Z/*bb background ( ≈ 102 signal ) has same diagrams!

(only slightly different angular distrib. because Z vector, h scalar)

difficult to be removed

bbZ → bbee as control sample:

good control sample to measure detector performance on signal:

• reco efficiency

• M() resolution

• b-tag performances

detector response differences

>e → more fake combinations with from bdifferent inner brehmsstralung

NZ→

NZ→ee

( )


ATLAS

ATLAS

Summary


For mH>140 GeV, ~1 fb−1 might be sufficient

For low mass higgs (< 140 GeV) situation more complex: ~ 5 fb-1 needed and several channels must be combined

Combined results


5 discovery

Exclusion limit @ 95% confid. level

CMS + ATLAS

These are inverse fbs of well understood data!!

detector systematics: jets, /, MET(e and from Z→ll)

multiple jets background xsec: V+jets, VV+jets, tt

Plot from: J.J.Blaising, A.De Roeck, J.Ellis, F.Gianotti, P.Janot, G.Rolandi and D.Schlatter

"Potential LHC contributions to Europe's Future Strategy at the High Energy Frontier"

Further reading…

• CMS physics TDR• ATLAS physics TDR• CMS note 2006/119 (ttH→ttbb)• CMS notes 2006/078, 2006/97, 2006/112 (H→)• CMS note 2006/088 (H→)• CMS note 2007/037 (H→WW)• CMS notes 2006/136, 2006/130, 2006/115, 2006/122 (H→4l)• ATLAS: "Prospect for a Higgs discovery in the channel H→WW→ll with

no hard jets" Mellado, Quayle, Wu• ATL-PHYS-PUB-2006-019 (Z→/Z→ee)


S. Bolognesi from CMS

DiscussionDiscussion



A. Di Simone from ATLASHiggs @ LHCHiggs @ LHC

Avoid fake discovery


If we have a deviation from the SM expectations, how we should react?If we have a deviation from the SM expectations, how we should react?

necessary prerequisites

good comprehension of the detector (commissioning and integration)

control of the systematics from standard candles (ex. Z,W for leptons)

measure background (normalization and shape) from data

clever tools to cross-check: comparison between similar channels (ex. e and )

work with ratios (ex: 4/2, 2/2e)

good comprehension of the MC tools (comparison between MCs, close dialogue with theoreticians)

prepare the analysis to make it possible!!prepare the analysis to make it possible!!

Weak points

H → ZZ → (CMS just starting, ATLAS done in the physics TDR)

ATLAS missing points: analysis sometimes based still on fast simulation Pileup & Cavern background effects often included but need to be studied systematically

Channels still to be addressed or just started

qqH → qqbb (VBF)

CMS missing points: jet reco performance still too low (energy flow work on-going) SUSY analysis should be more focused on real detector and low lumi scenarios

ttH → tt

Theoretical study with additional


DISEGNO qqbbg

Experimental study: (also fake) from fragmentation are not an issue(CMS Bologna using Pythia QCD sample)

Normalisation to ppZ2l

• SM single Z2l production cross-sections measured with great precision in an experiment which will have L ~ 10 fb-1.

• Calculate from MC the ratio R = (ZZ)/ (Z)– Full cancellation of LHC luminosities uncertainties– Partial cancellation of PDFs and QCD-scales

uncertainties– Partial cancellation of experimental uncertainties

• (extrapolated) = R• (Z)exp

• Discussion about using a similar approach in ATLAS too


• Theoretical and experimental uncertainty estimations for evaluation of background from single Z2e measurements

Normalisation to ppZ2l


Work on-going

CMS: • usage of CSA07 samples with misalignment/miscalibration in 10 pb-1 (100 pb-1) scenarios

ATLAS:

• study of lepton systematics from data in Z/W events (“2007 Notes”)to be extrapolated in the various Higgs channels

results to be published in the near future (“CSC Notes”)

develop strategy to measure from data:

• detector performances and systematics (standard candles as W and Z)

• backgrounds shape and normalization (tt,V+jets,VV+jets)

Focus on

real detector and LHC environment (PU) simulation

several issues (systematics, trigger, bkg from data) are being addressed for all the channels in the latest analysis


Beyond start-up

Mass and width

Ex. ATLAS: qqH → qqlnln / qq:

Test of EWSB mechanism through VBFEx. CMS: qqVV → qqVV → 6 fermions

• possible to distinguish SM from purely CP odd/even H to VV coupling

• possible to increase the limit on anomalous coupling

CP,spin through VBFEx. ATLAS: qqH → qqlnjj:

Ex. CMS: H→ e →ZZestimated precision <0.3% up to 350 GeV (stat error only) with 30 fb-1

if H

iggs

fou

nd

direct measurement with reasonable accuracy can be performed only above ~250 GeV (better than 10% for MH>300 GeV with 300 fb-1)

Ex. CMS + ATLAS: H→ZZ


Coupling to EW bosons through VBF

S. Bolognesi from CMS

Back-upBack-upslidesslides



A. Di Simone from ATLASHiggs @ LHCHiggs @ LHC

Higgs @ Tevatron

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Slide by F. Gianotti

Higgs @ CMS

improvement of the reconstruction

backgr. and syst. from data

Analysis focusing on

H→ZZ*→4l

H→WW*→ll

H→WW*→jjl / ll in VBF

H→ in VBF

early discovery channels

significance > 5(3) with 30 fb-1

H→

other channels (mainly associated production) can help EXCLUDING Higgs (e.g. WH→WWW*→Wll)

ttH→ttbb

measure Higgs properties (mass, width, xsec) already with 30 fb-1 !!

correct statistical treatment of results

but good comprehension of detector needed (jet, MET, in lept. and hadr. decay)

very difficult analysis with still quite unpredictable background

at least 60 fb-1 (many jets also with low pT (<30 GeV) → bad reso/eff)

channel studied MH

H→ ZZ*→4l H→ WW*→ll

H→ WW*→jjl

H→ H →

H→ WW*→llVB

F

5-100 fb 130-500 GeV

50-150 fb 115-145 GeV

50-100 fb 115-150 GeV

0.5-2.5 pb 120-200 GeV

200-900 fb 120-250 GeV50-250 fb 120-200 GeV

(σ×BR)O

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H →ZZ(*)→ 4l

one on-shell Z

very sensible for M(H) = 130 to 500 (except 150-190 where WW open)

2e 2: highest BR but lower reso/effic on electrons

4: golden channel

greater than 50% for M(H)>115

greater than 85% for M(H)>150

statistical observation involving a small number of events

compatibility with SM expectation:

early discovery:

preserving the phase space for more involved characterization measuring xsec, MH, width (spin, CP …)

three channels

4e: most difficult (important to recover low pT electrons)

isolated lepton from primary vertex with high pT (trigger)

usual cuts M(H)=130 GeV

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2e2 analysis backgrounds:

ZZ(*)/*, tt, Zbb

(Zcc found to be negligible)

likelihood approach to discriminate real / fake e+/-

internal bremsstrahlung recovery:• 40%-10% events with (pT>5 GeV) radiation from lepton (1/3 from )• recovered with R(,l) < 0.3

• e+e- with highest likelihood selected

• ECAL-Tracker matching, shower shape

reconstruction offline selection

bef

ore

afte

rmH=140GeV mH=200GeV

10 fb-1

Nsign≈ 12Nback≈ 2

Nsign≈ 36Nback≈ 16

10 fb-1

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2e2 results Background normalized from sidebands B = B stat B theory

B stat increases with mH from 2% (mH 120) to 30% (mH 600) because of events decreasing in sidebands w.r.t. signal window

B theory from PDF, QCD scale, NLO ZZ xsec → 0.5% - 4.5%

• mH 150 high BR and low backgrounds

• mH 170 low BR at the H→WW turn on

• mH 200 strong enhancement of BR for mH > 2mZ

• mH 250 decreasing of signal while ZZ background remains high• mH 250-350 decreasing of ZZ background • mH > 350 decreasing of signal xsec and BR (due to H→tt)

Luminosity VS mH (same shape of 4 and 4e)

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4 analysis

Half of the events used to optimize cuts with GARCON* which allows to obtain smooth M(4) dependent cuts:

three main critical cuts uncorrelated:

other half of the events used to compute significance

MC generated sample

mh150

• muon isolation• pT of the second lowest pT muon• M(4) window (≈ 2 where ≈ H + reso)

Reconstructed M(4) after selections channelZ

* t channel

* Genetic Algorithm for Rectangular Cuts OptimizatioN allows to check effectively a large set of cuts which, in a straightforward approach, would take an astronomical amount of time

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4 background systematicsRatio H→ 4 to Z→2 (≈ 1 fb-1) Normalization from sidebands

(lower systematics but bigger statistical error)

deep when b biggest

• new process NNLO gg→ZZ ≈ (20±8)% LO xsec (different initial state so variations of QCD scale do not necessary give a feel for its relative importance)

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4 results

complementary approaches

check the consistency with expected properties:

• M(4) shape consistency with sign+back hypothesis

• xsec and variables not used in the analysis

decrease a priori the open phase space:

• MH prior probability could be forced to be consistent with the fit to precision EW measurements

problem of significance overestimatimation of a local discovery in searching for a localized new phenomenon in a wide phase space

• use the early data for a first hint and then discard them from analysis

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4e analysisAfter trigger and preselection After full analysis selection

Nsignal ≈ 17

Nbackg ≈ 4

30 fb-1:

Optimization of low pT e+/- reco

cuts to reject fakes are separately optimized for different Bremsstr. e+/- classes

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4e: systematics & reults Use Z→e+e- with one golden e+/-, second e+/-

used to estimate uncertainties

1% uncertainty on reco, isolation and identif. efficiency

0.5% barrel (1% endcaps) uncertainty on energy scale

(best resolution on the Jacobian peak: pT ≈ mZ/2, low ||)

Tracker “radiography” measuring the amount of e+/- Bremsstralhung (2% material budget with 10 fb-1 )

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H→WW(*)→ll [M(H)=150-180]

No narrow peak →• good background shape control necessary (normalization from data)

• high S/B needed

signal: all leptonic W decays (0.5 - 2.3 pb with a peak at MH≈160 GeV)

WW, WZ, ZZ (≈ 15 pb)

tt, tWb (≈ 90 pb)

backgrounds:

Z Drell-Yan not considered but checked that after selection should be < 2% of the total background

• mass independent cuts

(ggWW)

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ll analysis central jet veto (||<2.5, ET>20 GeV)

ee, e, reconstruction and selection

intermediate m(ll) little (ll) in the transverse plane

no calibration (energy is not needed)

discrimination between real and fake jets (PU, UE, FSR, ISR, detector noise)

> 0.2 for jets with 15 < ET < 20 GeV

( )

( )T

T

p tracks

E jet

high MET (> 50 GeV)

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ll results

Similar promising analysis specifically in VBF channel:

B (tt) ≈ 16%B (WW) ≈ 17%dominated by statistic

dominated by jet energy scale

B from data defining free signal region varying the analysis cuts

(values for 5 fb-1)

B (WZ) ≈ 20% dominated by the presence of tt also

tWb, ggWW small fraction of B:• normalization region difficult to find• syst uncertainties from MC

theoretical error dominates (20%, 30%)

background normalized to signal free region (M(ll)>110)

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qqH with H→WW→ljj [M(H) = 120-250]

+ BR ≈ 5.5 BR(ll) → xsec ≈ 0.02 - 0.8 pb

+ you can reconstruct the Higgs mass

- big amount of background → strong cuts → good knowledge of physics needed (measure backgrounds from data) :

• tt + jets (≈ 840 pb)

multiple jets xsec will be precisely measured from data many systematics about jets will be understood and resolved from data

• Wtb (≈ 100 pb)

• VV + jets (≈ 100 pb)

• V + jets (≈ 700 pb)

30 fb-1

16% detector systematics

Loose Extra Jet Veto

Extra Jet Veto

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CMS qq + H→ljj : jets (1) Strong ET cuts needed

• Parton-jet matching efficiency

Strong ET cuts affect efficiency:

(jets with ET<30 GeV very difficult to calibrate)

• for keeping an acceptable resolution

• for eliminating fake jets (most of PU jets with ET<30 GeV)

mH = 170

signal forward quarks

signal quarks from W decay

(efficiency normalized to 1 for jet ET threshold of 16 GeV)

• Efficiency of requiring at least 4 jetstt + jets

W + 4 jets

W + 3 jets

signal

(efficiency normalized to 1 for jet ET

threshold of 20 GeV)

mH = 170

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tag jets misidentified with jets from FSR, ISR, PU, UE, detector noise …

In the signal this increases the chance of misidentification central jets from W

jets from W:

M(W→jj) using parton-jet matching

• best possible resolution of 15 GeV !!

• other central jets (ET>20 GeV in 60% of events) often (20%) with higher ET than jets from W

mH = 170

MC calibration from QCD jet samples Iterative cone algorithm (R=0.6)

Fast Simulation for some backgrounds

CMS qq + H→ljj : jets (2)

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qqH with H→→lep + jet [M(H)< 150]

forward jets with high rapidity gap (no color exchange)

high pT lepton (e or )

MET: resolution 20% after correction -jet identification

backgrounds: W→l + jets tt→blbl

with one jet misidentified as -jet

complex signal kinematics:

• MC calibration• central jet veto applied (with cut on parameter)

Z/* + jets (irreducible),

• offline

• trigger on little (R) isolated jet

impurity 2.7%

• energy resolution 11.3%

efficiency 30% (mainly due to pT, cuts and request of isolation)

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H→ results M() computed using collinear approximation of visible part of decay products and neutrinos

M() overestimated 5 GeV because of over-corrected MET M() resolution of 9.1%

number of events computed from data using the M() fit (envisaged to do it in a region unaffected from signal)

error (B) only from the fit:

Significance exceeds 3 at 30 fb-1

• 10k toy MC data distributions

• each sample refitted with free scale factors for the three independent fit• uncertainty = spread of the number of background events in the 10k samples

following the fit (with the number of events equiv. to 30 fb-1)

relaxed cuts

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Inclusive H→ [M(H)=115-150]

inclusive signal production but with very low BR≈0.002

pp→ (irreducible)

pp→ jets / + jets (reducible)with one jet misidentified as

Drell-Yan e+e-

very big background and very detector dependent + not well known QCD physics (big k factor in +jets events)

Analysis based on NN trained on sidebands for backgr.

on MC for signal

(1% systematic error on the background interpolation under the Higgs peak)

Great deal of uncertainty in the benchmark estimate of luminosity …

… this will not be a systematic error on real data since the background will be measured from data (thanks to the big sidebands signal free)

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Documents

S. Bolognesi (1) from CMS A. Di Simone (2) from ATLAS 1 Università di Torino ed INFN Torino 2 Università di Roma Tor Vergata ed INFN Roma 2 V workshop