higgs self coupling at e + e - linear collider
DESCRIPTION
Higgs self coupling at e + e - Linear Collider. P. Gay & Ph. Gris LPC Univ. B. Pascal -IN2P3. Introduction. Standard Model Higgs doublet ( f ) Higgs potential behaves as. the direct measurement of l hhh and indirect measurement from m h sign of NP. - PowerPoint PPT PresentationTRANSCRIPT
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 1
Higgs self coupling Higgs self coupling at eat e++ee-- Linear Collider Linear Collider
P. Gay & Ph. Gris LPC Univ. B. Pascal -IN2P3
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 2
IntroductionIntroduction Standard Model
Higgs doublet ()
Higgs potential behaves as 22
212 )()( V
GeV24622 4hm
22
23
26 / hhhh m
the direct measurement of hhh
and
indirect measurement from mh sign of NP
Goal
Reconstruction of the Higgs potential
Experimental establishment of the Higgs mechanism
Benchmark for detector optimisation
Deviation between
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 3
Standard ModelStandard Model
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 4
DetectorDetector simulation simulation EE
E1
jetjetjet EEE /%40/
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 5
Processes @ 800 GeVProcesses @ 800 GeV
CIRCE/ TESLA
Expected signal for 500fb-1 is ~92 events
Generated w/ WHIZARD Impact of the beamstrahlung
No beamstrahlung
Beamstrahlung and
complete
Mh=120 GeV/c2
visE
104000.2873keeZZ
0.057110khhZ tri
0.05369khh tri
71903.47725kZZ
13890668.89.2MWW
6744222.41.5MZZ
254000.78720ktt
117610.0912keZW
342800.72925kZZZ
175556.96100kWWZ
482712.4360kWW
706422.65160khZ
3840260.41Mtt
55214.52825kttZ
80062.49820ktth
542270.184410kSignal
NGenProcess
104000.2873keeZZ
0.057110khhZ tri
0.05369khh tri
71903.47725kZZ
13890668.89.2MWW
6744222.41.5MZZ
254000.78720ktt
117610.0912keZW
342800.72925kZZZ
175556.96100kWWZ
482712.4360kWW
706422.65160khZ
3840260.41Mtt
55214.52825kttZ
80062.49820ktth
542270.184410kSignal
NGenProcess
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 6
Selections Selections
Selection in two branches
Evis < 500 GeV Evis > 500 GeV
4 jets 6 jets
Preselection signal background
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 7
“ “hhZ”-SelectionhhZ”-Selection
2
56
Z56
2
34
h34
2
12
h122hhZ σ
mmσ
mmσ
mmD
2hhZD
2hhZD
Background
signal
ghhh
contribution
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 8
B-tagging B-tagging For each event a b-tagging per jet is performed
Based on impact parameter information per track, combined per jet, to form a probability Calibration is performed with the integral of the negative part of the distribution and yields the probability that the track is coming from a light quark
Impact parameters and jet multiplicity are combined in a multivariable estimator
NB: better estimator may be achieved with 3D view
Not sensible to the boost (only transverse information used)
Calibration has been done at 500GEV
No beamstrahlung
Beamstrahlung and
complete
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 9
““hhZ”-SelectionhhZ”-Selection
4
1
)1(i
jetbtag iNNT
signal Background
btagT btagT
ghhh
contribution
]1,1[ ijet
NN
No
b-l
ike
jet
4 b
-lik
e je
t
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 10
““hhZ”-SelectionhhZ”-Selection
eventNNeventNN
signal Background
ghhh
contribution
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 11
““hhZ”-SelectionhhZ”-Selection
signal
Background+signal
)/( 264 cGeVM jb
ghhh
contribution
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 12
““hh”-Selectionhh”-Selection
2
34
h34
2
12
h122hh σ
mmσ
mmD
2hhD
2hhD
First stage of the selection
Final stage of the selection
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 13
““hh”-Selectionhh”-Selection
angle measured in the cme of the pair between the higgs direction and the boost axis
*cos
*cos
signal
Background+signal
ghhh
contribution
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 14
Numbers Numbers hhZ-selection vvhh-sel. Total
Process loose Tight
tth 17.36 2.62 -
ttZ 10.14 1.81 -
tt 98.0 - -
hZ 16.1 - 1.41
eeZZ 0.43 - -
ZZ 0.07 - 0.49
ZZ 8.15 - 0.37
tt 0.04 - -
ZZZ 2.74 1.03 -
WWZ 0.28 - -
Backg 153. 5.46 2.27 7.73
signal 34.4 22.0 8.49 30.5
Eff. (%) 42.6% 30.2% 37.3% 33%
2.5 4.2 2.6 4.93sbs
for 500 fb-1
GeV800s
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 15
InterpretationInterpretation
Counting event only
hhZ channel (6jets) %22/ hh channel (4jets) %18/
for 2 ab-1
Process hhZ sel. vvhh-sel.
Backg 21.8 9.1
signal 88.0 34.
Eff. (%) 30.2% 37.3%
8.2 5.2sbs
‘hh’
‘hhZ’
Combination and likelihood
%14/ ghhh/g0
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 16
hhZ @ 500 GeV hhZ @ 500 GeV Main steps (similar to 800 GeV)
3 selections
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 17
hhZ @ 500 GeVhhZ @ 500 GeV
HHZ Cme=500Gev
Mh=120 Gev/C2 Full polarised beams
for 2 ab-1
Process hhZ sel.
Backg 105.6
signal 124
Eff. (%) 36%
8.1sbs
%18/
NN>0.5
likelihood
NN>0.5
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Higgs self coupling: a benchmark Higgs self coupling: a benchmark for detectorfor detector
Any improvements done on the the detector will save data taking
Impact of the Pflow resolution (fast simulation)
40%->30% move from 4.5 to 2 years data taking
LEP
E%30
E%40
E%60
BSS
LEP
E%30
E%40
E%60
BSS
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 19
Events clustered in 4 jets
Beamstrahlung included
GeVs 800@
1keeZZ
1kWW
1kWWZ
1khZ
1ktt
1kttZ
1ktth
1keeZZ
1kWW
1kWWZ
1khZ
1ktt
1kttZ
1ktth
Background “full simulation”~0.3 fb-1 simulated
Full simulationFull simulationLDC concept framework
MOKKA w/ HCAL sensitive material scintillatorParticle Flow Algorithm : Wolf in MARLIN RECO
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 20
hhZ @ 500 GeV
Event Display LDCEvent Display LDC
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 21
Full simulationFull simulation
Background
M34 (masse du Higgs)
20 Nbins entre 80 et 150 pour le background
PLOT
Background Background
Signal
12m 34m
GeVs 800@
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 22
Full simulation and ReconstructionFull simulation and Reconstruction
Reconstruction of is of importancePhotons are ~20% of jet energy
Motsly coming from
Challenge for calorimeters
Low energy photons
Example of improvement with
constraint on ° massGeVs 800@
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 23
Plo
ts g
iven
for
10
fb-1
“fast simulation” “full simulation”
“full simulation”
25 ab-1 simulated
Full vs Fast simulationFull vs Fast simulation
Background
Signal
GeVs 800@
Higgs & EWSB session LCWS06 8-13 march Higgs self coupling P. Gay 24
SummarySummary@ 500 GeV, selection of the events 6 jets have been performed to hhZ final state.
@ 800 GeV, selections of the events with 4 and 6 jets have been performed to respectively cover hh and hhZ final states
Beamstralhung & ISR has been taken in account Realistic Fast simulation of the detector has been used
At center of mass energy of 500 GeV, hhZ process leads to
combination of hhZ and vvhh channel, at center of mass energy of 800 GeV, leads to %14/
%18/
With 2 ab-1
Full simulation is on the way