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Exclusive DPE Higgs production at LHC

Marek Taševský (Physics Inst. Prague + Univ.Antwerp)ISMD 2005 - Kroměříž (Czech Republic) 15/08 2005

1. Comparison of DPEMC, ExHuMe and EDDE at parton, hadron and detector levels

2. New Roman Pot acceptances

3. Event yields for H->WW

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The Large Hadron Collider (LHC) PP collisions at s = 14 TeV

5 experiments

25 ns bunch spacing 2835 bunches 1011 p/bunch

Design Luminosity:1033cm-2s-1 -1034cm-2s-1

100 fb-1/year

23 inelastic eventsper bunch crossing

TOTEM

In LEP tunnel(circonf. 26.7 km)

Planned Startup: Summer 2007

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The CMS experimento Tracking

o Silicon pixelso Silicon strips

o Calorimeterso PbW04 crystals for Electro-magn.o Scintillator/steel for hadronic part

o 4T solenoido Instrumented iron for muon detection

o CoverageoTracking 0 < || < 2.5-3o Calorimetry 0 < || < 5

A Huge enterprise !

Main program: EWSB, Beyond SM physics…

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Roman pot acceptances

-t=10-1

-t=10-2

High * (1540m): Lumi 1028-1031cm-2s-1

>90% of all diffractive protons are seen in the Roman Pots. Proton momentum measured with a resolution ~10-3

Low *: (0.5m): Lumi 1033-1034cm-2s-1 220m: 0.02 < < 0.2 300/400m: 0.002 < < 0.02 (RPs in the cold region/FD420 under discussion in CMS/ATLAS)

TOTEM(ATLAS)

FD420

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For the first time at a collider large acceptance detector which measures the forward energy flow

1 day run at large beta (1540m) and L=1029cm-2s-1: 100 million minimum bias events, including all diffractive processes

>90% of all diffractive protons are detected

mic

rosta

tion a

t 19m

?

RPs

Total TOTEM/CMS acceptance (*=1540m)

CMS/TOTEM is the largest acceptance detector ever built at a hadron collider

TOTEM+CMS

T1,T2 T1,T2

Ro

ma

n P

ots

Ro

ma

n P

ots

Charged particles

Energy flux

CMS/TOTEM Study

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Diffraction at LHC:• PP scattering at highest energy • Soft & Hard Diffraction

< 0.1 O(1) TeV “Pomeron beams“ E.g. Structure of the Pomeron F(,Q2) down to ~ 10-3 & Q2 ~104 GeV2

Diffraction dynamics? Exclusive final states ? • Gap dynamics in pp presently not fully understood!

proton momentumlossmeasured in RPs

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Hgap gap

b

b -jet

-jet

Double Pomeron Exch. Higgs Production

Exclusive DPE Higgs production pp p H p : 3-10 fbInclusive DPE Higgs production pp p+X+H+Y+p : 50-200 fb

p p

Mh² measured in RP via missing mass as ξ1*ξ2*s bb: Jz=0 suppression of gg->bb bg | WW: bg almost negligible

E.g. V. Khoze et alM. Boonekamp et al.B. Cox et al. …V.Petrov et al.

Advantages of Exclusive:

bb: We need a L1-trigger of “central CMS+220 RP” type. Central detector is issueas CMS is not designed for low Et physics. Under study by CMS-Totem L1-tr. group

WW: Extremely promising for Mh>130 GeV: no trigger problems and a better Mhresolution for higher Mh.

(Wˉ)

(W+)

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DPE Higgs event generators

1. DPEMC 2.4 (M.Boonekamp, T.Kucs)

- Bialas-Landshof model for Pomeron flux within proton - Rap.gap survival probability = 0.03 - Herwig for hadronization

2. EDDE 1.2 (V.Petrov, R.Ryutin)

- Regge-eikonal approach to calculate soft proton vertices - Sudakov factor to suppress radiation into rap.gap - Pythia for hadronization

3. ExHuMe 1.3 (J.Monk, A.Pilkington)

- Durham model for exclusive diffraction (pert.calc. by KMR) - Improved unintegrated gluon pdfs - Sudakov factor to suppress radiation into rap.gap +

rap.gap survival prob.=0.03 - Pythia for hadronization

All three models

available now

in the fast CMS

simulation!

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Difference between DPEMC and (EDDE/ExHuMe) is an effect of Sudakov suppression factor growing as the available phase space

forgluon emission increases with increasing mass of the central system

Models predict different physics potentials !

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From Tevatron to LHC

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Fast CMS simulation: FAMOS

Main chapters: - Fastcalorimetry, FastElgamma, FastElMatching - FastTsim, FastBtag - FastJets, FastMET, FastHLTMET - FastMuon, FastMuonTrigger - FastTotem (just Roman Pots), FastCastor

Jet algorithm: o) Iterative cone o) Cone radius = 0.7

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FAMOS: Jet Energy Scale Correction

0 < |ηjet| < 1 1 < |ηjet| < 2

2 < |ηjet| < 3 |ηjet| > 3

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New Roman Pot acceptances for β*=0.55m

Update of RP acceptances for recent LHC optics V6.5

(V.Avati and K.Osterberg, Totem Note 05-2)

V6.5 V6.2β*=0.55m 0.5mx*=500μm 0 μmBeam X-angle=142 μrad 150 μradProton trajectories simulated with MADX

These acceptances recently put in FAMOS.

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Mh acceptance

Relative differencesbetween models decrease with Mh(from 40% to 15%for 420+220 comb.)

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H->bb, mh=120 GeV: Protons

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H->bb, mh=120 GeV: Protons

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H->bb, mh=120 GeV: Higgs

More central rapidity distr.of ExHuMe due to gluon distr. falling faster than Pomeron param. in DPEMC

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H->bb, mh=120 GeV: b-quarks after FSR

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H->bb, mh=120 GeV: hadron level

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H->bb, mh=120 GeV: detector level

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H->bb, mh=120 GeV: detector level b-jets

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H->bb, mh=120 GeV: detector level

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Excl.DPE H->bb: Event yields per L=30 fb-1

• Selection cuts at detector level for mh=120 GeV:0) Both protons accepted in one of two (220,420) RP stations1) Njet > 12) 45 < Etj1*JESCor < 85 GeV, Etj2*JESCor > 30 GeV3) |ηj1,2| < 2.54) |ηj1-ηj2| < 1.8

5) 2.8 < |φj1-φj2| < 3.48 The cuts still 6) Mj1j2/Mtot > 0.75 being optimized7) Mj1j2/Mmiss.mass > 0.88) Npart(3<|η|<6) = 09) 117 < Mmiss.mass < 123 GeV10) Both jets b-tagged (~40% total efficiency)Generator σxBR[fb] Acceptance gg->H->bb BG(gg-

>bb;gg->gg)DPEMC 2.0 50% EDDE 1.3 46% UNDER STUDY ExHuMe 1.9 57%

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ExHuMe: H->WW, mh=140 GeV: leptons

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ExHuMe: H->WW, mh=140 GeV: quarks

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Excl.DPE H->WW:Event yields per L=30 fb-1

- Both protons accepted in one of two RP’s (220, 420)- (L1 muons taken from FAMOS. El.+quarks correspond to parton level)

- Various cut scenarios acc.to current CMS L1 thresholds:

- Semi-leptonic W decay:- 1e (pt>29 GeV, |η|<2.5) or 1μ (pt>14 GeV, |η|<2.1) or- 1e (pt>20 GeV, |η|<2.5) + 2 quarks (pt>25GeV,|η|<5) or - 1μ (pt>10 GeV, |η|<2.1) + 2 quarks (pt>25GeV, |η|<5)

- Fully leptonic W decay:- 2e (pt>17 GeV, |η|<2.5) or 2μ (pt>3 GeV, |η|<2.1) or- eμ (pte>17 GeV, |η|<2.5 and ptμ>3 GeV, |η|<2.1) or - 2e (ptmax>29 GeV,|η|<2.5) or 2μ (ptmax>14 GeV,|η|

<2.1) or- eμ (pte>29 GeV, |η|<2.5 or ptμ>14 GeV, |η|<2.1)

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Excl. DPE H->WW: Event yield for L=30 fb-1

ExhuMe 1.3 and new RP acceptances

semi-lept fully-lept Mh[GeV] σXBR[fb] Acc.[%] cms atlas cms atlas

Total

120 0.37 57 0.2 0 1.2 1 1.3 135 0.77 62 0.6 3.1 3.4 140 0.87 63 0.6 1 3.5 3 3.8 150 1.00 66 1.0 4.9 5.3 160 1.08 69 1.0 1 6.0 5 6.6 170 0.94 71 1.0 5.4 5.9 180 0.76 74 0.8 1 4.5 4 4.9 200 0.44 78 0.6 1 2.9 2 3.2

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Summary

- Recent versions of DPEMC, EDDE and ExHuMe generators as well as new RP acceptances available in CMS fast simulation

- Working on optimizing the selection cuts for H->bb and H->WW channels. The H->WW channel looks promising for Mh>130 GeV. Unlike for H->WW, the L1-trigger and background for H->bb are issues and still need a lot of work. A common CMS-TOTEM L1-trigger working group established and studying this problem intensively

- Hot topic these days: Which model gives the best description of data??? The problem is that the only data available are those of Rjj distr. from CDF. More to come soon…