contents 1. introduction 2. analysis 3. results 4. conclusion constraint on new physics by measuring...
TRANSCRIPT
Contents1. Introduction2. Analysis3. Results4. Conclusion
Constraint on new physics by measuring the HVV
Couplings at e+e- LC
In collaboration with K.Hagiwara (KEK) and S.Dutta (Univ. of Delhi)
Yu Matsumoto (GUAS,KEK) 2007,12,13 @KEKPH07
H
V
V
1-1. Motivation
New Physics
SM
TeV scale Physics
・ Light Higgs
・ Heavy Higgs or Higgsless
SUSYLittle Higgs・・・
LHC LC
Tevatron LEP
Experiments
LHC can probe light Higgs scenario
1-2. Effective Lagrangian with Higgs doublet
,8dim7dim6dim5dim LLLLLL SMeff
contribute to majonara neutrino mass
contribute to four fermion coupling (Proton decay, 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
TeVf
LL ii
iSMeff 1,)6(
2
New physics effects. Here we considered only dimension 6
and the operators are …
We focused on this physics
1-3. dimension 6 operators including Higgs
are calculable in each particular modelsif
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
[
]))()(([
)1(2
)1(
,
Wz)6(
2
chWWHWHd
WHWbm
g
VZHZHcVHZbm
g
WHWgmaZHZmg
af
LL
WW
Z
Z
ZVVV
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 kSM
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
,kSMkEXP LN
if is given, we can calculate
1V iciii Vc
The large discrepancy between and
makes larger errors become small 1VSM )(i
kii
ikSMkTH cLLN )(
WWWZZZi dbabcbcbac ,,,,,,,, is 3-body phase space
2-0. Cross section
2-1 : WW-fusion → 500GeV,1000GeV
2-2: ZH production → 250GeV - 1000GeV2-3: ZZ-fusion → 500GeV,1000GeV
WWW dba ,, measurement
bcbcba ZZZ ,,,,
2-1. WW fusion process
The eigenvectors and eigenvalues of areV
awbw dw
GeVs 500 GeVs 1000
),(),(),(),( TdwWTbwWTawWTSMT
pydpybpyapydydpd
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 are
1500,500 fbLGeVs 1500,1 fbLTeVs
this means HWW coupling can be measured with 0.72% accuracy
There are strong correlation because of combining only one process.there is some combination of anomalous couplings which has a large error at each energy experiment.
1500,500 fbLGeVs
2-2. ZH production process
・ All couplings are independent
・ other couplings does not change so much because cross section decrease
・ cg 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
・ cg is most sensitive because its coefficient includes
s
s
),,(~
),,(
qqjj
qqjj
here
2-3. ZZ 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 :
strong correlation
The effect of ZH production process @250GeV 1. az 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 0.44% accuracy
)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 ZZ-fusion process
3.Constraints on dim6-Operators, & Comparison with other
experiments
Constraint from EW precision measurement
Our results (measurement at ILC)
Constraint from TGC (LEP L3)
Our 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(LEP)
(Our result)
4.Conclusion
We obtain the sensitivity to the ILC experiment on HVV couplings by using Optimal observable method
The expected accuracy of the measurements will be sensitive to quantum corrections
The t-channel processes
at high energy experiment are important, especially measure coupling
Hee Heeee
H
3-3. Luminosity uncertainty
The luminosity error will dominate the statistic uncertainty
Erro
r of a
z
]fb[L/1 1
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)
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