potential for measuring the vertex at colliders e.a., kanemura phys. lett. b626, 111(2005) e.a.,...
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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.
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
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 with ⇒ Littlest Higgs model (+ 1 complex triplet)
4. models with additional triplet with “⇒ Triplet model” (+ 1 complex triplet + 1 real triplet)
H W Z
Galison (84), Georgi, Machacek(85)Chivukula, Georgi(86)
1
1
Arkani-Hamed, Cohen, Katz, Nelson (02)Han, Logan, McElrath, Wang (03)
2 5(10 ) for tan 3 - 4 MSSMF O 2 3(10 ) for very low tan THDMF O
THDM2
F
Kanemura(99)
MSSM
Logan & Su(02)
models with additional doublet
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
37 GeV for 100 GeV
59 GeV for 500 GeV
71 GeV for 1 TeV
H
H
H
v m
v m
v m
2
2
2
0.26
0.64
0.96
F
F
F
: VEV of doublet
: VEV of triplet
v
vmodels with additional triplet
Chen, Dawson(03)
(+ 1 complex triplet)
(+ 1 complex triplet + 1 real 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 Higgs.
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 Higgs model,
3VBF 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 cuts
Signal: 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, ‥‥‥
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
Then, We estimate the required |F| values to satisfy S/√B > 3 for L=600 fb-1.
0 modeH W Z
modeH bt
2 2
2
Littlest Higgs (10 )
Triplet Higgs (1)
F O
F O
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
NG
OK
NG
NG
NG
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. Z 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: If go to ILC, possible to measure.
⇒ may be too heavy at ILC
⇒ possible to measure at ILC as well.
H
H
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, ‥‥‥
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, ‥‥‥