Search for the Higgs boson produced in vector boson fusion ...
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<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
<strong>Search</strong> <strong>for</strong> <strong>the</strong> <strong>Higgs</strong> <strong>boson</strong> <strong>produced</strong><br />
<strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong><br />
LHC<br />
Iris Rottländer<br />
University of Bonn<br />
Rencontres de Moriond<br />
QCD and Hadronic Interactions<br />
March 21 st , 2007<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
LHC, ATLAS & CMS<br />
LHC: First collisions 12/2007 (ECM =900 GeV)<br />
14 TeV <strong>in</strong> 2008<br />
Initial lum<strong>in</strong>osity: 210 33 /(cm 2 s) ⇒ 10fb 1 /year<br />
Design lum<strong>in</strong>osity: 10 34 /(cm 2 s) ⇒ 100fb 1 /year<br />
CMS: central barrel<br />
wheel arriv<strong>in</strong>g <strong>in</strong><br />
underground cavern<br />
Not studied <strong>for</strong> VBF so far !<br />
Two multipurposeexperiments <strong>for</strong> wide physics range:<br />
ATLAS: All components completed<br />
Installation <strong>in</strong> cavern well progressed<br />
CMS: Installation on surface completed<br />
Lower<strong>in</strong>g <strong>in</strong>to cavern ongo<strong>in</strong>g<br />
ATLAS cavern webcam<br />
Both experiments will be ready <strong>for</strong> first<br />
collisions on time !<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
Vector Boson Fusion<br />
(qqqqH)<br />
Second largest <strong>Higgs</strong> <strong>boson</strong><br />
production channel at <strong>the</strong> LHC<br />
Promis<strong>in</strong>g <strong>for</strong> discovery<br />
(clean signature)<br />
Contribute to coupl<strong>in</strong>g<br />
measurement<br />
[fb]<br />
10 4<br />
10 3<br />
10 2<br />
qqqqh bbh<br />
qbqth<br />
ggh<br />
qqWh<br />
gg,qqtth<br />
qqZh<br />
SM <strong>Higgs</strong> prod.<br />
100 200 300 400 500<br />
mh [GeV/c 2 ]<br />
LHC √s=14<br />
TeV<br />
50 100 200<br />
particle mass (GeV)<br />
rate ev/year<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
VBF Signature<br />
Two tag jets <strong>in</strong> <strong>for</strong>ward region<br />
⇒ To be found up to 1° to beam pipe<br />
(Jets partially <strong>in</strong> beam pipe)<br />
⇒ Pileup & underly<strong>in</strong>g event effects?<br />
No color flow between quark l<strong>in</strong>es ⇒ Central jet veto<br />
⇒ Pileup & underly<strong>in</strong>g effects?<br />
<strong>Higgs</strong> <strong>boson</strong> decay products <strong>in</strong> central region<br />
Significant background suppression!<br />
pp ZjjX<br />
Zeppenfeld et al.<br />
QCD bkgd<br />
* 3 = 3 - <br />
(Centrality of third jet)<br />
<strong>Higgs</strong> signal M=160GeV<br />
tt background ATLAS<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007<br />
*<br />
1/ d/d 3<br />
Arbitrary units<br />
signal<br />
- 4 -2 0 2 4<br />
- 4 -2 0 2 4<br />
Rapidity of tag jets
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
Experimental Per<strong>for</strong>mance<br />
Jet Tagg<strong>in</strong>g Efficiency<br />
ATLAS<br />
PT,Jet>20GeV<br />
<br />
Central Jet Veto<br />
CMS<br />
H<br />
PT,Cut=10 GeV PT,Cut=45 GeV<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
qqqqH, Hlh+3 / ll+4<br />
Low <strong>Higgs</strong> <strong>boson</strong> masses important<br />
<strong>Higgs</strong> <strong>boson</strong> – fermion coupl<strong>in</strong>g<br />
F<strong>in</strong>al state lepton <strong>for</strong> trigger<strong>in</strong>g<br />
Mass reconstruction despite<br />
neutr<strong>in</strong>os <strong>in</strong> f<strong>in</strong>al state<br />
(“Coll<strong>in</strong>ear approximation”)<br />
BR<br />
1<br />
10 -1<br />
10 -2<br />
10 -3<br />
10 -4<br />
50 100 150 200 250 300 350 400<br />
MH (GeV)<br />
Ma<strong>in</strong> backgrounds:<br />
reduced by jet veto<br />
reduced by<br />
mass reconstruction<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
Signal peak near Zpeak:<br />
Nevts (30fb -1 ) / 5GeV/c 2<br />
5<br />
4<br />
3<br />
2<br />
1<br />
qqqqH, Hlh+3 / ll+4<br />
CMS<br />
lh<br />
30 fb -1<br />
Signal<br />
EW/QCD 2+jets<br />
ttbar, W+jets<br />
MH=135GeV<br />
Sig=3.9<br />
Mass resolution (910%) dom<strong>in</strong>ated by PTmissresolution<br />
Significances at 30 fb 1 0 50 100 150 200 250<br />
M [GeV/c<br />
:<br />
CMS : lh, MH=135 GeV ⇒ Sig = 3.9<br />
e, MH=125 GeV ⇒ Sig = 4.0<br />
ATLAS : lh, MH=130 GeV ⇒ Sig = 4.4<br />
lh+ll, MH=130 GeV ⇒ Sig = 5.7<br />
2 ]<br />
background<br />
uncerta<strong>in</strong>ty 710%<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007<br />
evts / 5GeV<br />
ATLAS, e, 30 fb -1<br />
Signal<br />
Zjj<br />
tt, WW EW<br />
MH=120GeV<br />
Sig=2.5<br />
M (GeV)
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
qqqqH, HWW<br />
W offshell or onshell<br />
<strong>Higgs</strong> <strong>boson</strong> mass close to production<br />
threshold ⇒ W<strong>boson</strong>s have low PT<br />
Many & large background processes<br />
(tt+jets, W+jets, Z+jets, WW+jets,<br />
ZZ+jets, QCD multijets...)<br />
Clean access to <strong>Higgs</strong>WWcoupl<strong>in</strong>g<br />
Example background processes<br />
BR<br />
ATLAS<br />
Example cut variable: ll<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007<br />
1<br />
10 -1<br />
10 -2<br />
10 -3<br />
10 -4<br />
Arbitrary units<br />
50 100 150 200 250 300 350 400<br />
MH (GeV)<br />
Signal mH=160GeV/c 2<br />
tt background<br />
WW el. weak<br />
WW QCD
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
30<br />
Number of Events<br />
5<br />
0<br />
qqqqH, HWWljj<br />
Significances:<br />
CMS: Sig>5.0 <strong>for</strong> MH≈140200 GeV at 30 fb 1<br />
ATLAS: Sig=4.6 <strong>for</strong> MH=160 GeV at 30 fb 1<br />
Mass resolution (CMS) 1424 GeV<br />
CMS, 60 fb -1<br />
100 150 200 250 MH (GeV)<br />
VBF <strong>Higgs</strong> mass distributions from signal<br />
only, MH=160/190/220 GeV<br />
Number of Events<br />
Signal<br />
background<br />
uncerta<strong>in</strong>ty 1016%<br />
CMS, 60 fb -1<br />
MH =170GeV<br />
Background<br />
100 150 200 250 300<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007<br />
50<br />
40<br />
30<br />
20<br />
10<br />
0<br />
MH (GeV)
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
qqqqH, HWWll<br />
No mass peak can be reconstructed ⇒ transverse mass<br />
Significances:<br />
CMS: Sig>5.0 <strong>for</strong> MH≈140190 GeV at 30 fb 1<br />
ATLAS: Sig>5.0 <strong>for</strong> MH≈125190 GeV at 30 fb 1<br />
d/dMT (fb/10GeV/c 2 )<br />
0.2<br />
0.1<br />
ATLAS<br />
WWe<br />
MH=120GeV<br />
<strong>Higgs</strong> signal<br />
bkgd<br />
tt+Wt bkgd<br />
WW bkgd<br />
MT = √2PT ll ETmiss(1cos )<br />
background<br />
uncerta<strong>in</strong>ty 710%<br />
Background<br />
MT (GeV/c 2 ) MT (GeV/c 2 0<br />
0 50 100 150 200 250<br />
0<br />
0 50 100 150 200 250<br />
)<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007<br />
d/dMT (fb/10GeV/c 2 )<br />
1<br />
0.75<br />
0.50<br />
0.25<br />
ATLAS<br />
WWe<br />
MH=160GeV<br />
<strong>Higgs</strong> signal<br />
bkgd<br />
tt+Wt bkgd<br />
WW bkgd
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
qqqqH, H<br />
Low branch<strong>in</strong>g ratio, clean signal<br />
Background processes:<br />
+jets, Zee, QCD jets, ...<br />
Photon Id. & isolation crucial<br />
⇒ Realistic fake rates needed<br />
Narrow mass state ( res≈0.7% )<br />
⇒ reconstruct <strong>Higgs</strong> <strong>boson</strong> vertex<br />
⇒ Sig≈1.52.5 (30 fb 1 )<br />
(Higher significances reached <strong>for</strong><br />
<strong>in</strong>clusive H)<br />
BR<br />
1<br />
10 1<br />
10 2<br />
10 3<br />
10 4<br />
Events (x40)<br />
50 100 150 200 250 300 350 400<br />
MH (GeV)<br />
CMS<br />
MH=130GeV<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007<br />
160<br />
140<br />
120<br />
100<br />
80<br />
60<br />
40<br />
20<br />
0<br />
122 126 130 134 138<br />
<strong>Higgs</strong> <strong>in</strong>variant mass, GeV
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
Signal significance<br />
10 2<br />
10<br />
1<br />
ATLAS<br />
∫Ldt = 30fb -1<br />
LO Xsecs<br />
(no K-factors)<br />
Overall Discovery Potential<br />
H<br />
ttH(Hbb)<br />
▴ H ZZ (*) 4l<br />
HWW (*) l l<br />
qqHqqWW (*)<br />
▴ qqHqq<br />
Total significance<br />
100 120 140 160 180 200<br />
mH (GeV/c 2 )<br />
NLO <strong>Higgs</strong> Xsecs<br />
NLO background Xsecs<br />
when available<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
tan<br />
40<br />
30<br />
20<br />
10<br />
7<br />
5<br />
3<br />
2<br />
1<br />
VBF & MSSM<br />
ATLAS prelim<strong>in</strong>ary<br />
30 fb 1<br />
100 300 500 700 900<br />
MA (GeV)<br />
One neutral, CPeven<br />
<strong>Higgs</strong> <strong>boson</strong> (h, H)<br />
observable with VBF<br />
at 30fb 1 <strong>in</strong> many<br />
benchmark scenarios<br />
VBF has good chances <strong>for</strong><br />
discover<strong>in</strong>g a<br />
supersymmetric<br />
<strong>Higgs</strong> <strong>boson</strong>! (if it exists)<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
Summary & Conclusions<br />
VBF important <strong>Higgs</strong> <strong>boson</strong> discovery channel at LHC<br />
Prospects well evaluated by CMS & ATLAS collaborations<br />
Experimental challenges:<br />
Forward jet reconstruction<br />
Central jet veto<br />
<strong>Higgs</strong> mass resolution (ETmiss, JetPT, vertex reconstruction, ...)<br />
Important decay channels:<br />
H promis<strong>in</strong>g <strong>for</strong> 5 discovery <strong>for</strong> 120135 GeV<br />
HWW promis<strong>in</strong>g <strong>for</strong> 5 discovery 125190 GeV<br />
H : evidence possible at 23 level<br />
VBF processes cover tanMA plane well <strong>for</strong> many MSSMscenarios<br />
Ma<strong>in</strong> Sources:<br />
SNATLAS2003024<br />
CMSTDR0082 + cited papers<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
BACKUP SLIDES<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
CMS + ATLAS detectors<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
Central Jet Veto + Tagg<strong>in</strong>g jets<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
MSSM coupl<strong>in</strong>gs<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007
<strong>Search</strong> <strong>for</strong> <strong>Higgs</strong> <strong>produced</strong> <strong>in</strong> <strong>vector</strong> <strong>boson</strong> <strong>fusion</strong> processes at <strong>the</strong> LHC<br />
Hadronic Wmass reconstruction<br />
MH =170GeV<br />
CMS<br />
30 50 70 90 110 130<br />
Hadronic W-mass (GeV)<br />
=14.8 GeV<br />
Iris Rottländer Rencontres de Moriond, 21 st March 2007
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