Transcript LCWS08_ByYuMatsumoto

Presice measurement of the
Higgs-boson electroweak couplings
at Linear Collider
and its physics impacts
Yu Matsumoto (KEK)
V
V
H
2008,11,18 @LCWS08
Contents
1. Introduction
2. Conclusions
3. Analysis
4. Results on operators
5. Conclusions
In collaboration with K.Hagiwara (KEK) and S.Dutta (Univ. of Delhi)
1-1. Motivation
Tevatron
LEP
SM
・W, Z-boson discovery
・top-quark discovery
・W,Z boson precision measurements
New physics theories
・Light Higgs scenarios
LHC
LC
NP1
NP3
・LHC can probe light Higgs scenario
・precision measurements of
the Higgs-boson properties
NP2
NP9
NP5
NP11
NP4
NP7
・Heavy Higgs or
Higgsless scenarios
NP10
NP6
NP8
NP13
NP12
1-2. Effective Lagrangian with a Higgs doublet
New physics can be represented by higher mass dimension operators
Leff  LSM  Ldim5  Ldim6  Ldim7  Ldim8  ,
contribute to majonara neutrino mass
contribute to
four fermion coupling (Proton decay, etc)
purely gauge term (Triple gauge coupling, etc)
Higgs electroweak couplings
We focused on this physics
We can write the effective Lagrangian including Higgs doublet as
Leff  LSM
f i ( 6)
  2 i
i 
and the operators are …
New physics effects. Here we consider only dimension 6
1-3. dimension 6 operators including Higgs
Precision measurement
(SLC, LEP, Tevatron)
2 point function, TGC, vertices include Higgs boson
Dimension 6 operators
LC
LHC
Triple gauge couplings
(LEP2,Tevatron)
f i are calculable in each particular models
2. Conclusions
The most accurately measured combinations of dim-6
operators are sensitive to the quantum corrections
(EWPM)
(ILC our result)
ILC experiment can constrain completely different
combinations of dim-6 operators from EWPM
We can select new physics by multi-dimensional operator space
These accuracy of the combinations are not affected from
systematic errors ex) luminosity uncertainty
e  beam polarization plays an important role
to obtain high accuracy
High energy experiments ( s  500GeV ) are important for
the measurements of HZ  couplings
3-1. Optimal observable method
The differential cross section can be expressed by using non-SM couplings
ci  ciZZ , c2 Z , c3 Z , c2 , ciW W , i  1,2,3
 is 3-body phase space
d
  SM   ci  i ()
d
i
k
N EXP
 L SM k ,
number of event in the k-th bin
for experiment and theory
k
NTH
 L SM k  L ci i ()k
i
 2 can be expressed in terms of non-SM couplings
 L ci  i ( k ) k
 N k  N k (c ) 

2
TH
i 
 2 (c1 ,, cn )    EXP
  min
  i
k


L SM  k
k
k 
N
EXP



2
  ci c j L
i, j
if
V 1
 i ( k ) j ( k )
k
 SM ( k )
is given, we can calculate
ci  Vii
ci
2


2
   min


2
2
 k   min
  ci (V 1 ) ij c j   min
i, j
The large discrepancy between
makes V
1
larger
 SM
and  i ()
errors become small
3-2. Operators and Vertices, Form Factors
We exchange the operators into HVV interaction vertices as the experimental observables

f
g m
Leff  LSM   i2  i( 6 )  (1  c1ZZ ) Z Z HZ  Z   (1  c1WW ) gmW HWW 
2
i 
g
 Z  [c2 ZV HZ V   c3 ZV ((  H ) Z  ( H ) Z  )V  ]
mZ V  , Z

c
gZ

[c2W W HW
W    3W W (((   H )W  ( H )W )W    h.c.)]  
mZ
2

※ ci  ciZZ , c2 Z , c3 Z , c2 , ciW W

are the linear function of f i
： EW precision, S and T parameter
： Triple Gauge Couplings
3-3. Cross section
f 1 , f 2 , f 4
WW-fusion ciW W
fW
fW W
double-tag eeH
ciZZ
ZH production
f 1 , f 2 , f 4
fW , f B
fW W, f BB , f BW
double-tag eeH
single-tag eeH ciZ
ZH production
no-tag (ee)H
c 2 
High s
experiment
f i
fW , f B
～ ILC phase I
phase II
fVV
fW , f B
fW W , f BB , f BW
fW W , f BB , f BW
polarization
no-tag
(ee)H
3-4. Luminosity uncertainty
Here we set
L is true luminosity
 2 can be redefined as
Luminosity uncertainty is absorbed into
c1ZZ , c1W W
errors
c
c
The correlation between 1ZZ and 1W W
is generated through luminosity uncertainty
c1W W  c1ZZ  f 1
The measurement of
f 1
doesn’t depend on
f
4-1. constraint on dim-6 operators (1)
① EWPM results
1 dimensional
② ILC-I+ILC-II with | Pe  | 0.8, | Pe  | 0.0, f  0.01, Ltotal  1200 fb
1
s : 250,350,500,1000
L : 100,100,500,500
5 dimensional
③ ILC-I with
| Pe | 0.8, | Pe | 0.0, f  0.01, Ltotal  700 fb1
④ ILC-I (250,350GeV) with | Pe  | 0.8, | Pe  | 0.0, f  0.01, Ltotal  700 fb
s : 250,350,500
L : 100,100,500
1
s : 250,350
L : 350,350
4-2. Constraints on dim6-Operators (2)
combining with LEP and future experiments
EWPM will be also improved at ILC experiments
@ LEP2,Tevatron (present EWPM)
if
@ ILC
+
@ GigaZ
The results combining our HVV measurements at ILC and EWPM at ILC are
+
5. Conclusions
We obtain the sensitivity to the ILC experiment on 8 dim-6
operator space by using Optimal observable method
 
 
 
The t-channel processes of e e   H and e e  e e H
at high energy experiment are important to measure
HWW , HZ  and H couplings
Polarization is important to obtain high accurate measurement
on HZ  coupling
Luminosity uncertainty affects c1ZZ , c1WW measurements, but
only one combination of the operators, 3 f 4  2 f 2 is affected
The expected accuracy of the measurements will be sensitive
to quantum corrections as same accuracy as EWPM.
And its constraints are in the multi dimensional space.