1 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
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. - PowerPoint PPT Presentation
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>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
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)
- 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…