Post on 17-Jan-2016
Contents1. Introduction2. Analysis3. Results4. Conclusion
Presice measurement of the Higgs-boson electroweak couplings at Linear Collider and its physics impacts
Yu Matsumoto (GUAS,KEK) 2008,3,5 @TILCW,Z,γ
0H
W,Z,γ
In collaboration with K.Hagiwara (KEK) and S.Dutta (Univ. of Delhi)
1-1. Motivation
New Physics
SM
TeV scale Physics
・ Light Higgs
・ Heavy Higgs or Higgsless
SUSYLittle Higgs・・・
LHC LC
Tevatron LEP
Experiments
If the light Higgs exists, LC can probe the detail properties of the Higgs boson
Theory
W, Z, top discovery
W and Zmass & couplings
Higgs discoveryHiggs partner
WW scattering
Precise measurements of Higgs couplings
1-2. Effective Lagrangian with Higgs doublet
,8dim7dim6dim5dim LLLLLL SMeff
contribute to majonara neutrino mass
contribute to four fermion coupling (Proton decay, FCNC, etc) purely gauge term (Triple gauge coupling, etc) Higgs electroweak couplings
New physics can be represented by higher mass dimension operators
We can write the effective Lagrangian including Higgs doublet as
)6(2 i
i
iSMeff
fLL
New physics effects. Here we considered only dimension 6
and the operators are …
We focused on this physics
are calculable in each particular modelsif
1-3. dimension 6 operators including Higgs
Dimension 6 operators
2 point function, TGC, vertices include Higgs boson
Precision measurement (SLC, LEP, Tevatron)
Triple gauge couplings (LEP2,Tevatron)
LH
C
LC
.)].))()(((2
[
]))()(([
]))()((22
[
)1(2
)1( WWZZ)6(
2
chWWHWHc
WHWbm
g
AZHZHcAHZbm
g
ZZHZHc
ZHZb
m
g
WHWgmaZHZmg
af
LL
WWWW
Z
Z
ZZZ
Z
ZZZZ
Z
Z
WZZ
ii
iSMeff
We exchange the operators into HVV interaction vertices as the experimental observables
※ are the linear function of
if
1-4. Operators and Vertices, Form Factors
WWWZZZ dbabcbcba ,,,,,,,,
: EW precision, S and T parameter
: Triple Gauge Couplings
jijiji
SM
ji
jijik
k kSM
kjki
jiji
k kkSM
ikkii
kkEXP
ikTH
kEXP
n
cVcdLccLcc
L
cL
N
cNNcc
,
1
,,
22
12
)( )(
)()(
)(
)()(
)(
)()(
),,(
1-5. Optimal observable methodThe differential cross section can be expressed by using non-SM couplings
can be expressed in terms of non-SM couplings
)()( i
iiSM c
d
d
number of event in the k-th bin for experiment and theory
2
,)( kkSMkEXP LN
if is given, we can calculate
1V iciii Vc
The large discrepancy between and
makes larger errors become small 1VSM )(i
kkii
ikkSMkTH cLLN )()(
ZZZWWZZZWWZZWWi cccbbbbaac ,,,,,,,,is 3-body phase space
2-0. Cross section
2-1 : WW-fusion → 250GeV-1000GeV
2-2: ZH production → 250GeV - 1000GeV
2-3: ZZ-fusion → 250GeV,1000GeV
WWWWWW cba ,, measurement
ZZZZZZZZ cbcba ,,,,
2-4: γγ-fusion → 500GeV,1000GeV
Zγ-fusion → very small effect~ ILC phase I
phase II
GeVmH 120
bcbcba ZZZZZZZZ ,,,,,
b
bcb ZZ ,,
2-1. WW fusion process
The eigenvectors and eigenvalues of areV
a b c
GeVs 500 GeVs 1000
),(),(),(),( TcWWTbWWTaWWTSMT
pycpybpyapydydpd
In WW fusion process, the out going fermions are neutrinos.The observable distributions should be
y y y
Tp
The results combining each collision energy with beam polarization are 1100,250 fbLGeVs
1500,1 fbLTeVs
this means HWW coupling can be measured with 0.72% accuracy
There are strong correlation because there is a combination of anomalous couplings which has a large error at each energy experiment.
1100,350 fbLGeVs1500,500 fbLGeVs
1100,250 fbLGeVs1100,350 fbLGeVs
1500,500 fbLGeVs
0,0 ee PP
There are still strong correlation
2-1-2. Combined Results(1)
2-2. ZH production process
・ other couplings does not change so much because cross section decrease
・ become more sensitive when is increase
)~()(
2
1)
~()(
2
1
iii
iSMSM cd
d
i
iiSM cd
d)()(
GeVs 250
GeVs 500
The differential cross section is expressed as
・ az cannot be measured independently
・ is most sensitive because its coefficient includes s
s
),,(~
),,(
qqjj
qqjj
here
for llZ
for qqZ
ZZZ cc ,
4 constraints for 5 couplings
Zc
2-3. eeH double-tag Z,Zγ,γγ fusion process
GeVs 500
GeVs 1000
Final fermions are electron. we can use full information of
)(i
i
iiSM cd
d)()(
995.0cos e GeVepT 1)( Double e+ e- tag
conditions :
Because the distribution of is same to SM
ZZa
6 constraints for 6 couplings
→ all couplings can be measured independently
2-4. (ee)H no-tag γγ fusion processParametrize the cross section by using the equivalent real photon fusion
event contamination from WW fusion process
pTH resolution is set to 3 GeV
here
is SM 1-loop contribution
The effect of ZH production process @250GeV 1. cannot be measured independently at one energy experiment 2. New physics term is proportional to Correlation goes small by combining other processes
It is possible to measure HZZ coupling with 0.32% accuracy
)( ZZ cb
1100,350 fbLGeVs
1100,250 fbLGeVs
1500,500 fbLGeVs
1100,350 fbLGeVs
1100,250 fbLGeVs
1500,500 fbLGeVs1500,1 fbLTeVs
Combined results with ZH process and eeH double-tag, (ee)H single-tag process with beam polarization 0.0||,8.0|| ee PP
2-5. Combined results (2)
ZZa
Combine up to with
2-5. Combined results (3)Comparison with polarization and
0||,0.0|| ee PP 0.0||,8.0|| ee PP
0.0||,0.0|| ee PPTeVs 1Combine up to with
0.0||,8.0|| ee PPTeVs 1
・ Strong correlation disappears→ all couplings are measured independently
)%0004.0,002.0,02.0(),,(
)%006.0,03.0,3.0(),,(
bcb
cba
ZZ
ZZZZZZ
Each couplings are measured with below accuracy
)%14.0,76.0,72.0(),,( WWWWWW cba
・ dose not change by beam polarization
baZZ ,
・ The error of become much smaller when polarized beam is applied
ZZZZ cbc ,,
40/1
15/1
4/122
22
WBZ
WWWBBWZ
WWBWZZ
ffc
fcfsb
fcfsc
3-1. Constraints on dim6-Operators,
& Comparison with other experiments
Constraint from EW precision measurement
measurement @ ILC
Constraint fromTGC (LEP L3)
ILC results are enough.
EW precision measurement gives stronger constraint about a several factor.
ILC is required Luminosityat ab-1 scale to get comparable constraint
LC is hopeful for reducing the anomalous Triple Gauge Coupling
most constrained combination
(EWPM)
(ILC)
4. Conclusion
We obtain the sensitivity to the ILC experiment on HVV couplings by using Optimal observable method
The expected accuracy of the several dim6 operator combinations will be sensitive to quantum corrections
The t-channel and no-tag processes at high energy experiment are important to measure and couplings
HHZHWW ,
The polarization of electron beam make the constraint on much stronger. And the all couplings are measured very accurately with relating small correlation.
),,( ZZZZ cbc
(EWPM)
(ILC)
)13.0(22.0
)02.0(059.01
BWf
f)11(026.0
)3.5(016.0
B
W
f
f
075.0)23(
35.0
14.0
24
ff
f
f
BB
WW
(EWPM)
(TGC)
3-2. Luminosity uncertainty
The luminosity error will dominate the statistic uncertainty
df become dominant error.To make statistic error and df to be same contribution, df<0.005 is required especially at ab-1 scale.
df < 1% is required to get the error of az around 1%
region1fb100L region1fb100L
※ If df → 0 :
Redefine inverse of the covariance matrix with considering Luminosity uncertainty (=df)
GeVs 250
Comparison with polarization and
0.0||,0.0|| ee PP 0.0||,8.0|| ee PP
0.0||,0.0|| ee PP
0.0||,8.0|| ee PPwith
GeVs 250 with
Comparison with polarization and
0||,0.0|| ee PP 0||,8.0|| ee PP
TeVs 1
0.0||,0.0|| ee PP
0.0||,8.0|| ee PPwith
TeVs 1 with
2-5. e(e)H single-tag Zγfusion processParametrize the cross section by using the equivalent real photon for un-tagged side
For 500 GeV
For 1 TeV
Add the contribution of this process to the total Single-tag process is sensitive to and
totalV 1
b )( cb
3-3. ILC measurement Contribution to the Tz and Sz
When the ILC measurements is combined, it gives more strong constraint on the dSz and dTz