Potential for measuring the vertex at colliders

E.A., Kanemura Phys. Lett. B626, 111(2005)E.A., Kanemura, Kanzaki hep-ph/0612271

Eri Asakawa (KEK)

1. Introduction2. The vertex3. Measuring the vertex at LHC4. Measuring the vertex at ILC5. Summary

H W Z

H W Z

Exploring Higgs sector What members are included? (mass? charge? parity? CP property?) What is the mass relation among the members like? What kind of couplings do Higgs bosons have?

gives us a clue to understand physics beyond SM.

2 neutral Higgs bosons (H and A)a pair of charged Higgs bosons

ex.) MSSM : + one doublet Littlest Higgs model : + one triplet

・・・

If Higgs sector is extended by adding a doublet,

for an additional doublet

will be observed.

1. IntroductionMany models beyond SM predict extended Higgs sector as a low energy effective theory.

It is necessary that Higgs mechanism should give the gauge bosons their masses.

W W

Z Z

<Φ> <Φ>

<Φ> <Φ>

2 2g gW hhWWm

22

2

gg

cosZ hhZZW

m

Already measured2

2 21

cosW

Z W

m

m

†

†

† 2 23 3

g gg sin g sin

cos cos

kin

W WW W

L D D

W T W T T Z W T W T T Z

Source of the gauge boson masses = Source of the Higgs-gauge couplings

Source of the gauge boson masses

W W

Z Z

<Φ>

<Φ>

g ghWW hhWW

g ghZZ hhZZ

should be measured after Higgs detection

2

g1

g coshWW

hZZ W

= Source of the Higgs-gauge couplings

In SM,

h

h

v h iz

W W

Z Z

2Wm

1

For the models with extended Higgs sector

W W

Z Z

1 1

1 1

2 2

2 2

+

+

+ ‥‥

+ ‥‥2Zm

W W

Z Z

i

i 1h

: mass eigenstatesih

1h

1

1

2

g1

g coshWW

h ZZ W W W

Z Z

i

i 2h

2h

2

2

2

g1

g cosh WW

h ZZ W

observable afterHiggs detection ↓

Higgs-gauge couplings

the gauge boson masses

observable afterHiggs detection ↓i

i

i

i

So, the measurements of the couplings ghWW and ghZZ

can be used to explore the structure of the Higgs sector.

The coupling gH±WZ can also be used.

W Z

<Φ> H±

In models extended by doublet(s),

W Z W Z

01

02

+ + = 0‥‥

H± H±

because the rotation of the Higgs fields below is always possible:

Z Z

01

02

+H± H±

W W+ ‥‥

Z Z

01

02

+H± H±

W W+ ‥‥

0 0where 0,

and

i h v

Z

0h ω±

W

Diaz-Cruz, Lopez-Falcon (03)

However, in models extended by greater representations than doublet,

W Z W Z

01

02

+ + ‥‥

H± H±

0

vertex depends on models.H W Z

additional doublet : zero at tree level (loop induced)additional triplet : non-zero

We discuss predictions of the vertex in 4 types of models. 1. models with additional doublet (more constrained) ⇒ MSSM

2. models with additional doublet (less constrained) ⇒ THDM

3. models with additional triplet without custodial symm. ⇒ Littlest Higgs model (+ 1 complex triplet)

4. models with additional triplet with cutodial symm. “⇒ Triplet model” (+ 1 complex triplet + 1 real triplet)

H W Z

Galison (84), Georgi, Machacek(85)Chivukula, Georgi(86)

Arkani-Hamed, Cohen, Katz, Nelson (02)Han, Logan, McElrath, Wang (03)

And, Potential for measuring the vertex in these models are studied.

2. The vertexH W Z

dim. 5dim. 3

dominant

. .Weff HWZ HWZ Z HWZ Z WL f H W Z g H F F h i H F F h c

2 5(10 ) for tan 2 - 4 MSSMF O 2 3(10 ) for very low tan THDMF O

THDM2

F

Kanemura(99)

MSSM

Logan & Su(02)

models with additional doublet

160 GeVHm

2 2

2 2

cos 8W

vF

v v

W

4

cos

vF

v

Littlest Higgs model

“Triplet model”

the bound from the ρparameter etc. puts upper limit for v5 GeV for 1 TeV

4 GeV for 2 TeV

v f

v f

2

2

0.0085 700 GeV

0.0054 1.56 TeV

H

H

F m

F m

the bound from the Zbb results puts upper limit for v3

3

3

40 GeV for 100 GeV

63 GeV for 500 GeV

77 GeV for 1 TeV

H

H

H

v m

v m

v m

2

2

2

0.26

0.65

0.97

F

F

F

: VEV of doublet

: VEV of triplet

v

vmodels with additional triplet

Chen, Dawson(03)

(+ 1 complex triplet + 1 real triplet)

(+ 1 complex triplet)

2 2

2

Littlest Higgs (10 )

Triplet Higgs (1)

F O

F O

2 5

2 3

MSSM (10 )

THDM (10 )

F O

F O

Prediction for upper limits of the vertex is hierarchical for models.

H W Z

How small F values can be observed at LHC and ILC?

E.A., Kanemura (2005)

Charged Higgs production at LHC

for light

for heavy

t bH

t bH

t H b H m m m

p p H t b X H m m m

3. Measuring the vertex at LHCH W Z

H

t

b

g

W

Z

→ ｊ ｊ

→ l l→ b l v

010 fb Br H W Z 310 for MSSM

⇒

It may be possible to measure the vertex for MSSM and THDM.But need Htb coupling, then useless for “Triplet Model”.

production via W Z fusionH

Partonic process

proton

proton

Forwardregion

Forwardregion

Central region

Central region

Small hadronic activity except for jets from produced Higgs bosons　　　 　⇒　 possible to reach THDM case???

Pure electroweak process with no color flow in the central region.

W

Z

For no-Htb-vertex models like “Triplet model”,

4VBF 1 10 pb

production 490 pb

production 26 pb

O

t t

WZ

Event generation : PYTHIA , MadGraph

Simulation : under the expected detector performance at LHC

Tools

S/B is extremely huge!!

We perform the simulation study for the WZ fusion.

So, effective event selection is indispensable.

E.A., Kanemura, Kanzaki (2006)

0H W Z j j lv

500 GeVHm

,

,

Event selection cuts which we impose for

Before cuts After cutsSignal: 100%BG W+4j: 100% (130 pb)BG ttbar: 100% (490 pb)

Signal: 0.2%BG W+4j: 0.003% (3.5 fb)BG ttbar: 0.0001% (0.5 fb)

BG: W+4j, ttbar, ‥‥‥

VBF

b-tag

lepton

H

W

90 GeVZ

jj

500 GeV

800 GeVHm

Before cuts After cuts

Signal: 100%BG W+4j: 100% (130 pb)BG ttbar: 100% (490 pb)

Signal: 0.4%BG W+4j: 0.0016% (2.1 fb)BG ttbar: 0.0001% (0.5 fb)

Before cuts After cutsSignal: 0.1%BG W+4j: 0.04% (56 fb)BG ttbar: 0.0008% (3.9 fb)

Signal: 100%BG W+4j: 100% (130 pb)BG ttbar: 100% (490 pb)

200 GeVHm

500 GeVHm

Before cuts After cutsSignal: 100%BG W+4j: 100% (130 pb)BG ttbar: 100% (490 pb)

Signal: 0.2%BG W+4j: 0.003% (3.5 fb)BG ttbar: 0.0001% (0.5 fb)

0H W Z j j lv

0 modeH W Z

modeH bt bt

2 5

2 3

2 2

MSSM (10 )

THDM (10 )

Littlest Higgs (10 )

F O

F O

F O

Predictions for each model

Predictions for each model

← OK

Then, We estimate the required |F|2 values to satisfy S/√B > 3 for L=600 fb-1.

2 2

2

Littlest Higgs (10 )

Triplet Higgs (1)

F O

F O

2 5

2 3

MSSM (10 )

THDM (10 )

F O

F O

4. Measuring the vertex at ILCH W Z

Charged Higgs production at ILC

γ,

H W Z includethe vertex

THDM MSSM

Logan & Su(02)Kanemura(99)

⇒may be possible to reach even in MSSM case !!

5. Summary

H W Z The vertex is important because it directly depends on the global symmetry structure of the models.

Prediction for the vertex is hierarchical for models. Therefore, measuring the vertex is useful to test the models.

We performed the simulation study for the production process via WZ fusion at LHC.

2 5

2 3

2 2

2

MSSM (10 )

THDM (10 )

Littlest Higgs (10 )

Triplet Higgs (1)

F O

F O

F O

F O

NG

OK

NG

NGResults:

H

　 may be possible to measure in decay (bg→H± ｔ ) and ILCH

0H W Z j j lv

800 GeVHm

Before cuts After cuts

Signal: 100%BG WZjj: 100% (560 fb)BG WZ: 100% (26 pb)

Signal: 0.09%BG WZjj: 0.036% (0.1 fb)BG WZ: (< 0.003 fb)

Before cuts After cutsSignal: 0.02%BG WZjj: 0.008% (0.02 fb)BG WZ: (< 0.003 fb)

Signal: 100%BG WZjj: 100% (560 fb)BG WZ: 100% (26 pb)

200 GeVHm

500 GeVHm

Before cuts After cutsSignal: 100%BG WZjj: 100% (560 fb)BG WZ: 100% (26 pb)

Signal: 0.03%BG WZjj: 0.004% (0.02 fb)BG WZ: (< 0.003 fb)

0H W Z l l lv BG: WZ j j, WZ, ‥‥‥

0H W Z l l lv

200 GeV

500 GeV

Hm

Hm

800 GeVHm

H bt bblv

200 GeV

700 GeV

Hm

Hm

Before cuts After cutsSignal: 0.3%BG WZjj: 0.004% (18 fb)

Signal: 100%BG ttbar: 100% (490 pb)

Before cuts After cutsSignal: 1.1%BG WZjj: 0.0008% (4 fb)

Signal: 100%BG ttbar: 100% (490 pb)

BG: ttbar, ‥‥‥

H bt bblv 200 GeV

700 GeV

Hm

Hm

The extended Higgs sector is strongly constrained　 from experiments (ρparameter, FCNC, )‥‥‥

additional doublet : at tree leveladditional triplet :

1 1 22

2

22 2 2

4 ( 1)

cos 2

i i i i iW i

Z W i ii

T T Y v cm

m Y v

L:SU(2) isospin

: hypercharge

: v.e.v.

i

i

i

T

Y

v

for each Higgs representation

:1 for complex representation

1/2 for real representationic

vertex depends on models.H W Z

additional doublet : zero at tree leveladditional triplet : non-zero

4 2 2 2

22 2 22 2

4 14

Z ZHWZ i i i i i

iW

g m g mf Y T T Y v

m

: mass eigenstatesi i i i

i

v h iz

h

THDM Littlest HiggsTriplet Higgs

Higgsless