17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics1 Discovery Potential...
-
date post
21-Dec-2015 -
Category
Documents
-
view
215 -
download
0
Transcript of 17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics1 Discovery Potential...
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 1
Discovery Potential ofthe SM Higgs at the LHC
Junichi TanakaICEPP, University of Tokyo
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 2
Contents
LHC and ATLAS SM Higgs
Production cross section and branching ratio VBF process
Key issues Tau identification TauID performance
Discovery potential with ~10/fb (~1 year run) MSSM : Lighter Neutral Higgs Conclusions
CMS, Triggers, SUSY -> Roberto.C’s talk
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 3
What is the LHC?
Proton-Proton (pp) Collider 14TeV
• 27km LHC tunnel• Installed in the existing LEP tunne
l
• 1232 superconducting dipoleswith B = 8.3 T working at 1.9 Kelvin
• Two general-purpose pp experimentsATLAS vs CMS
14m x 1232
image
Dipole magnet
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 4
Geneva Airport
LHC tunnel (27km in circumference)( ~100m underground)
CERN
Swiss side
France sideJura Mountains
Large Hadron Collider
ATLAS CMS
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 5
ProcessEvent rate at 2×1033
2007-8 L=10fb-1
Comparison(estimation at
2007)tt 1.6 Hz 107 104 Tevatron-2
bb: PT>10GeV200 KHz
(HLT 10Hz)2×1012
(108 inc. di-)109 Belle/BaBar
Higgs (130GeV)
200/h 5×105 ---------
SUSY (1TeV) 20/h 5×104 ---------
At the first year 2007~8 (L=10fb-1)
LHC is Top & B-factory.
LHC can be Higgs & SUSY factory!!!
Why is the LHC?
- Discovery of SM Higgs~ the last unobserved particle
- Discovery of New Physics
Measurement ofSM Higgs properties etc.
High energy High luminosity
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 6
Time Schedule of LHC• April, 2007 : first beam, commissioning• September, 2007 : 7 months with L=2x1033 cm-2s-1 ” Low luminosity” r
un
Physics : L=10fb-1 -> Higgs/SUSY?
• 2007~2009 : Low luminosity run• ~2009 : L=1034 cm-2s-1 ”High luminosity” run
Sep. 11th, 2004ATLAS
ATLAS has started theinstallation of the detector.
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 7
ATLAS (A Toroidal LHC ApparatuS)
• Inner tracking system : 2T solenoid magnet• Liq. Ar EM calorimeter• Muon spectrometer : air-core troidal magnet
E,P resolution (P ~ 100GeV) :
~ 2% e, ~ 1.5%Jets ~ 8%
•40MHz beam crossing•Readout channel = 160M channels•Raw data = 320Mbyte/sec (1TB/hour)
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 8
SM Higgs Production at LHCGluon Fusion
Vector Boson Fusion (VBF)
Excluded by LEP
Associated WH, ZH
Associated ttH, bbH
VBF
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 9
SM Higgs Decay
bb, , , WW, ZZare important at the lowmass region.
Observation of Higgs by multi modes
114.4 < mH < 193 GeV/c2 @95% C.L.
LEPEWWG Summer2003
Branching ratios
Can study Higgs properties in detail.
Couplings…
Difficult but interesting!
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 10
Vector Boson Fusion Process
Characteristics High Pt jets in forward region Rapidity gap <- no color flow : no jet activitiesQCD background can be reduced by these features.
VBF H-> at low-mass region (mH = ~120GeV) Large production cross section and branching ratio Can reconstruct M(=mH) -> Can see a peak-> Discovery channel!!
Rapidity gap
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 11
Branching ratio of H-> :• BR(lep-lep) = ~12%• BR(lep-had) = ~46%“Lep-had” mode plays an important role for the Higgs discovery.
MH =120GeV
h
4M Distributions of VBF H->
Hadronic tau decay mode
factor of ~4
(e only)
CMS
ATLAS
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 12
Key Issues : Strategy for Discovery
For “VBF H->->lep,had” channel : More signals
Tau jet identification High efficiencies of tau jets with high rejection power of QCD jets
Less backgrounds Missing Et
Better resolution Make a tail of Z smaller Make a signal peak shaper
ATLAS
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 13
Tau-jet identificationTau-jet = jet originated from hadronic tau decay We need to identify tau-jets from many QCD-jets.
Properties of tau-jet Hadronic decay modes of tau Narrowness Shower shape related with decay products (0,+-) of
Number of charged tracks
Next slide
Studying now
Most/Half of energy are deposited at EM.
Charged tracks : 1 or 3Photons from 0
Can be measured at InDet.
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 14
Fraction of energy in R<0.1
20 < Pt < 30
40 < Pt < 5070 < Pt < 130Tau-jetsQCD-jets
R<0.4
R<0.1 ~90% of energy are depositedin R<0.1. -> narrow jet
ET(R<0.1)ET(R<0.4)
(transverse energy)
These distributions depend on luminosity due to the pile-up.
ATLAS, preliminary
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 15
TauID Performance
No new result.-> studying …
ATLAS TDR 1999
We achieved eff=50% withRejection factor > ~100 forPt > ~40GeV.
We misidentify one QCD jetas a tau jet in ~100 QCD jets.
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 16
Production Decay Mass region and purpose
Gluon FusionH -> 110-140GeV Mass
H -> ZZ-> 4 l 140-1000GeV Discovery, Mass, Spin, Coupling
H -> WW 130-170GeV Discovery
Vector BosonFusion
H -> 110-140GeV Discovery, Mass, Coupling
H -> WW 130-200GeV Discovery, W coupling
H -> 110-140GeV Discovery, Mass
H -> bb 110-140GeV Yb coupling
ttH
H -> bb 110-130GeV
Yt couplingH -> 110-130GeV
H -> WW 130-180GeV
WH H -> WW 140-170GeV Discovery, W coupling
Summary of SM Higgs StudiesATLAS
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 17
Discovery potential of SM Higgs
Can discover Higgs withL=30fb-1 by >8(MH>114GeV:LEP limit)
MH < 200GeV:- Light case: VBF - Heavy case: VBF WW- Can observe Higgs
by multi-modes.
MH >200GeV:- H->ZZ->4lepton by >20
ATLAS
~5 with L=10fb-1
-> Discovery of Higgs within ~ 1 year
10fb-1
30fb-1
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 18
Discovery potential of SM Higgs
CMS
10fb-1
30fb-1
60fb-1
~5 with L=10fb-1 -> Discovery of Higgs within ~ 1 year
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 19
MSSM : Lighter Neutral Higgs
CMS
The lighter neutralhiggs h ~ SM Higgs
h mass increases withmA, tan, top mass,stop mass, stop mixing.
bbh coupling is enhanced stronglyat large tan.
h->, and bb+
17th Sep 2004@Nara, JapanTau04 - International workshop on Tau Lepton Physics 20
VBF process becomes important for the Higgs discovery in the low-mass region, mH=110~130GeV. Higher efficiency of tauID with a high purity is necessary to
discover Higgs as early as possible. We need to confirm our tauID using 10fb-1 of real data, Z->
. Study of missing Et is also important.
Conclusions SM Higgs can be discovered within 1 year ~ L=10fb-1
at both ATLAS and CMS.
LHC will start at 2007!-> SM Higgs!! and New Physics@TeV!!