Higgs Dark M atter amp Its Collider Signals E Asakawa M Asano K Fujii T Kusano S M R Sasaki Y Takubo and H Yamamoto PRD 79 2009 S M ID: 333030
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Slide1
Little
Higgs
Dark Matter & Its Collider Signals
・ E. Asakawa, M. Asano, K. Fujii, T. Kusano, S. M., R. Sasaki, Y. Takubo, and H. Yamamoto, PRD 79, 2009.・ S. M, T. Moroi and K. Tobe, PRD 78, 2008.・ S. M, M. M. Nojiri and D. Nomura, PRD 75, 2007.・ M. Asano, S. M., N. Okada and Y. Okada, PRD 75, 2007.
Shigeki Matsumoto(University of Toyama)
Little Higgs Scenario
Little Higgs signals at LHC & ILCSummary
～ Papers ～
～
Contents
～Slide2
1. Little Hierarchy Scenario
Kolde & Murayama, hep-ph/0003170
When the tuning < 10%,
ΛSM < O(1)TeV (mh = 120 GeV)Corrections to mh If coefficient ci is O(1), ΛSM > O(10)TeV (mh = 120 GeV)EW ObservablesBarbieri & Strumia, 1998
E
1 TeV10 TeV
???
Little Hierarchy Problem
Need some mechanism to control the Higgs mass!
1/11Slide3
1. Little Hierarchy Scenario
Little Higgs Scenario・ Higgs boson = Pseudo NG boson
・ Explicit breaking = Collective symmetry breaking New Physics with G ( ⊃ Gauge group ),which is slightly broken Electroweak breaking SU(2) x U(1)Y U(1)EM (
Standard Model)
E
1 TeV
100 GeV10 TeV
SSB: G G’, where G
’ ( ⊃ SU(2) x U(1)
Y
)
Generation of m
h
Origin of m
h
=
Interactions which break G.
Usual breaking:
When the interaction
“L
1
“
breaks the symmetry G,
and generates m
h
, then
(m
h
)
2
～
(Λ
SM
)
2
/(16π
2
)
～
(1 TeV)
2
(1-loop diagrams)
2/11Slide4
1. Little Hierarchy Scenario
Little Higgs Scenario・ Higgs boson = Pseudo NG boson
・ Explicit breaking = Collective symmetry breaking New Physics with G ( ⊃ Gauge group ),which is slightly broken Electroweak breaking SU(2) x U(1)Y U(1)EM (
Standard Model)
E
1 TeV
100 GeV10 TeV
SSB: G G’, where G
’ ( ⊃ SU(2) x U(1)
Y
)
Generation of m
h
Origin of m
h
=
Interactions which break G.
Collective symmetry breaking:
When the Interactions
“L
1
“
& “L
2
“
(partially) break G,
and the Higgs boson is
“pseudo” NG boson when both interactions exist,
(m
h
)
2
～
(Λ
SM
)
2
/(16π
2
)
2
～
(100 GeV)
2
(2-loop diagrams)
2/11Slide5
1. Little Hierarchy Scenario
W,Z
W
H,ZHhhhh+++h
tt
tTQuadratically divergent corrections to m
h are completely cancelled at 1-loop level!
Diagrammatic view point
・ Global symmetry imposed・
Collective sym. breaking
New particles introduced.
(Little Higgs partners)
T
E
1 TeV
100 GeV
10 TeV
SM
Nonlinear sigma model
Constructing models
3/11Slide6
1. Little Hierarchy Scenario
– F
2
/4 + LYukawa – V(H, F) + Kinetic terms of fermionsLagrangianNo quadratically divergent |H|2 term at 1-loop level.----
-
--
--
--
-Triplet
H
H
H
T
+
SU(5
)
SO(5
)
[SU(2)
xU
(1)]
2
SU(2)
xU
(1)
4/11Slide7
1. Little Hierarchy Scenario
Constraints from EWPM
Littlest Higgs
model suffers from EWP constraints. ～ Imposition of the Z2-symmetry (T-parity) ～ 1. SM particles & Top partner T+ are even 2. Heavy Gauge bosons are odd. 3.
T-odd partners of matter fields introduced
. H. C. Cheng, I. Los, J. High Energy Phys. (2003, 2003)
-
-
---
-
-
-
-
-
-
-
Triplet
H
H
H
T-parity
T
+
T
–
4/11Slide8
1. Little Hierarchy Scenario
Constraints from EWPM
H. C. Cheng, I. Los, J. High Energy Phys. (2003, 2003)
----------
--
Triplet
H
HH
T-parity
T
+
T
–
Model
Parameters of the LHT
f
: VEV of the SU(5)
SO(5) breaking
l
2
: Mass of the top-partners (in units of
f)
k
x
: Mass of the T-odd partner of “x”(in units of f
)
Higgs mass m
h
is treated as a free parameter
4/11Slide9
1. Little Hierarchy Scenario
Constraints from EWPM
H. C. Cheng, I. Los, J. High Energy Phys. (2003, 2003)
Model Parameters of the LHT f : VEV of the SU(5) SO(5) breakingl2 : Mass of the top-partners (in units of f)kx : Mass of the T-odd partner of “x”(in units of f) Higgs mass mh is treated as a free parameter
Masses of new particles are proportional to f.
Masses of SM particles are proportional to v. O (f)
O (v)
4/11Slide10
1. Little Hierarchy Scenario
Lightest T-odd Particle is stable due to the T-parity conservation.
Little Higgs Dark Matter! (Heavy photon in the LHT)
Main annihilation mode: AH AH h WW or ZZ1. AHAHh vertex is given by the SM gauge coupling.2. Annihilation cross section depends on mAH & mh. Relic abundance of AH: Wh2
(mAH
(f), mh)
Asano
, S.M, N.Okada, Y.Okada (2006)J. Hubisz, P. Meade, Phys. Rev. D71, 035016 (2005)
Little Higgs dark matter issinglet and spin 1 particle.
The dark matter mass:
80-400 GeV
The Higgs mass:
110-800 GeV
W
h
2
of dark matter
5/11Slide11
1. Little Hierarchy Scenario
U-branch
Constraints from EWPM?
6/11Slide12
1. Little Hierarchy Scenario
Constraints from EWPM?
L-branch
6/11Slide13
1. Little Hierarchy Scenario
1. Masses of top partners are
about (or less than) 1 TeV! copiously produced at the LHC.2. Masses of heavy gauge bosons
are several hundred GeV! can be produced at the ILC. f = 580 GeV l2 = 1.15 mh = 134 GeVmT+ = 834 GeVmT-
= 664 GeV mAH
= 81.9 GeVmWH = 368 GeVm
ZH = 369
GeVRepresentative point
6/11
Constraints from EWPM?
L-branchSlide14
2. Littlest Higgs Signals at LHC & ILC
Top partner productions
S.M., T. Moroi, K. Tobe, Phys.Rev.D78 (2008
)LHC is a hadron collider, sothat colored new particlesare copiously produced! T+ & T- productions!MadGraph/Event (Event generation) PYTHIA (Hadronization) PDG4 (Detector Response)
T
+ pair production
Reconstructing twoT
+-system, T+(lep
) & T–(had
)
Determination of T
+
Mass
(with ±20 GeV uncertainty)
7/11Slide15
2. Littlest Higgs Signals at LHC & ILC
Top partner productions
S.M
., T. Moroi, K. Tobe, Phys.Rev.D78 (2008)LHC is a hadron collider, sothat colored new particlesare copiously produced! T+ & T- productions!MadGraph/Event (Event generation) PYTHIA (Hadronization) PDG4 (Detector Response)
Single T
+ production
Reconstructing bW system
# of the signal depends on NP!(σ determined with 20% accuracy.)
7/11Slide16
2. Littlest Higgs Signals at LHC & ILC
H
1
H2Top partner productionsS.M., T. Moroi, K. Tobe, Phys.Rev.D78 (2008)LHC is a hadron collider, sothat colored new particlesare
copiously produced!
T+ & T- productions!
MadGraph/Event (Event generation)
PYTHIA (Hadronization) PDG4 (Detector Response)
Top reconstruction via
hemisphere analysis.
End points of M
T2
depend on m
T-
& m
AH
(within about 20 GeV accuracy.)
T
-
pair production
S.M., Nojiri, Nomura (2007)
0
100
200
7/11Slide17
2. Littlest Higgs Signals at LHC & ILC
f = 580
±
33 GeV Cosmological connectionsf (GeV)l2From T+
pair prod.
From T+ single prod.From T
- pair prod.
1s3s
8/11Slide18
2. Littlest Higgs Signals at LHC & ILC
Heavy gauge boson productions
E. Asakawa, M. Asano, K. Fujii, T. Kusano, S. M., R. Sasaki, Y. Takubo, and H. Yamamoto, PRD79, 2009.
ILC is a e+e- collider, so thatheavy particles are producedwith clean environment. WH, ZH, AH productions! Physsim (Event generation) PYTHIA (Hadronization) JSF Q-sim. (Detector Response)
Z
HAH
production @ 500 GeV
Energy distribution of h End points depend on mAH & mZH
mAH
= 83.2 ±
13.3 GeV
m
ZH
= 366. ±
16. GeV
f
= 576. ±
25. GeV
s
= 1.9 fb
9/11
500 fb
-1Slide19
2. Littlest Higgs Signals at LHC & ILC
Heavy gauge boson productions
E. Asakawa, M. Asano, K. Fujii, T. Kusano, S. M.,
R. Sasaki, Y. Takubo, and H. Yamamoto, PRD79, 2009.ILC is a e+e- collider, so thatheavy particles are producedwith clean environment. WH, ZH, AH
productions!
Physsim (Event generation) PYTHIA (Hadronization) JSF Q-sim. (Detector Response)
Z
HA
H production @ 1 TeV Energy distribution of W
End points depend on m
AH
&
m
ZH
m
AH
= 81.58 ±
0.67 GeV
m
WH
= 368.3 ±
0.63 GeV
f
= 580±
0.69 GeV
s
=
１２１
fb
9/11
500 fb
-1Slide20
2. Littlest Higgs Signals at LHC & ILC
Probability density
Simulation results
+ Higgs massAnnihilation X-section<sv>(mAH, mh) WDMh2Probability density ofthe dark matter relicsWDMh2WMAP
Planck
LHC
ILC(1000)
ILC(500)LHC: Abut 10% accuracy (Model-dependent analysis)
ILC(500): Better than 10% accuracy (Model-independent analysis)ILC(1000): 2% accuracy!! (Model-independent analysis)
10/11Slide21
11/11
3. Summary
Little Higgs model with T-parity is one of attractive scenario describing New Physics at TeraScale.It contains a candidate for cold dark matter whose stability is guaranteed by the T-parity (Little Higgs dark matter).
The property of the dark matter can be investigated at collider experiments such as LHC & ILC.At LHC, top partners can be detected. From their data, the property of the dark matter can be estimated with a model dependent way.At ILC with s1/2 = 500 GeV, the property of the dark matter can be determined with model-independent way. Also, the relic abundance can be determined with the accuracy comparable to the WMAP.AT ILC with s1/2 = 1 TeV, the property of the dark matter can be determined very accurately. For instance, the relic abundance will be determined with the accuracy comparable to PLANCK experiment.Slide22
Back UpSlide23
The LH Lagrangian
Pseudo NG bosons
Breaking directions
– F2/4 + LYukawa – V(H, F) Non-linear s field+ Kinetic terms of fermionsSlide24
The LH Lagrangian
Gauge interactions [SU(2) x U(1)]2
– F
2/4 + LYukawa – V(H, F) Gauge couplings: g1, g’1, g2, g’2Slide25
The LH Lagrangian
– F
2/4 + LYukawa – V(H, F)
Top Yukawa interactions
Top Yukawa:
l1U quark mass:
l2
tLtRSlide26
Particle contents in Gauge, Higgs, and top sectors
4 gauge bosons : B1, W1 , B2, W2Σ= (24 – 10) pions
: SM gauges : A, W±, ZHeavy gauges : AH, WH±, ZH SM Higgs : h Triplet Higgs : ΦAfter breakingsSM top quark : t , Heavy top : T = (U , UR)Tg1, g’1, g2, g’2l1, l2Parameters
fSlide27
Little Higgs Dark Matter
Lightest T-odd Particle is stable due to the T-parity conservation.
Little Higgs Dark Matter! (Heavy photon in the LHT)
Main annihilation mode: AH AH h WW or ZZ.1. AHAHh vertex is given by the SM gauge coupling.2. Annihilation cross section depends on mAH & mh. Relic abundance of AH:
Wh2
(mAH(f), mh
)
[Asano, S.M, N.Okada, Y.Okada (2006)]
[J. Hubisz, P. Meade, Phys. Rev. D71, 035016 (2005) ]
When m
h
< 150 GeV,
then 550 < f < 750 GeV.
Masses of heavy gauge bosons
are several hundred GeV.
can be produced at ILC.
Masses of top partners are
about (or less than) 1 TeV
copiously produced at LHC.
W
h
2
(m
AH
(f), m
h
)Slide28
Representative point for simulation study
(1) Observables (m
w sinqW
, Gl, WDMh2) vs. Model parameters (f, l2, mh)(2) 2mh2/mt > O(0.1-1), where mt is the top-loop contribution to m
h.
Considering EW precision & WMAP constraints
f = 580 GeV
l2
= 1.15 mh = 134 GeV
m
AH
= 81.9 GeV
m
WH
= 368 GeV
m
ZH
= 369 GeV
m
T+
= 834 GeV
m
T-
= 664 GeV
m
F
= 440 GeV
(
m
LH
= 410 GeV)
[J.
Hubisz, P. Meade, A. Noble, M. Perelstein, JHEP0601 (2006)]Slide29
T
+
pair production at the LHC
SM BG: tt–production! (460 pb)-At the parton levelSignal = bbqqlν-- Reconstruct Two T+-system: T+(lep) & T–(had) using the fact that the missing momentum pT is due to the neutrino emission and (pl + pν)2 = mW2. There are 6-fold ambiguity in the reconstruction of T+-system.The combination to minimize
~ Output ~Distribution of
~ Strategy to reduce BG ~Slide30
T
+
pair production at the LHC The distributions have distinguishable peaks at around the T+ mass. SM BG are well below the signal.
From the distribution, we will be able to study the properties of T+.~ Results ~~ Cut used in the analysis ~~ Discussion ~Slide31
T
+ pair production at the LHC
We consider the binThen, we calculate the # of events in the bin as a function of with being fixed. The peak of the distribution is determined by maximizing the # of events in the bin. We applied the procedure for~ Results ~
~ Conclusion ~~ Accuracy of the mT+ determination ~ The difference between the position of the peak and the input value of mT+ is, typically, 10-20 GeV! Slide32
T
+
single production at the LHC
SM BG: tt & single t productions!-At the parton levelSignal = bqlνExistence of very energetic jet (b from T+)!With the leading jet, reconstruct T+-system.There are 2-fold ambiguity to reconstructneutrino momenta & Reject events unless is small.Jet mass is also used to reduce the BG. ~ Output ~Distribution of
~ Strategy to reduce BG ~Slide33
Single T
+
production occurs not through a QCD process but through a EW process (e.g. W-exchange). Distributions have distinguishable peaks at around the T
+ mass when sin2β is large enough! From the cross section, we will be able to determine sinβ.~ Results ~~ Cut used in the analysis ~~ Discussion ~T+ single production at the LHCSlide34
We use the side-band method to extract the # of the single production events,
(L)
(C) (R)after imposing the cuts. Then, cross section for the single T+ production can be obtained from the # of events in the signal region.~ Results (Point 2) ~~ Conclusion ~
~ Accuracy of sinβ determination ~ The cross section, which is proportional to sin2β, will be determined with 10-20%. Parameter “sinβ”, which is given by a combinationof f & λ2, will be determined with 5-10% accuracy!T+ single production at the LHCSlide35
T
–
pair production at the LHC
SM BG: tt–production! (460 pb)-At the parton levelSignal = (bqqAH)×21. Large missing momentum is expected in the signal event due to dark matter emissions.2. Use the hemisphere analysis to reconstruct the top quark [S.M., Nojiri, Nomura (2007)].3. Since AH is undetectable, direct masurements of T– & AH are difficult. MT2 variable! ~ Output ~Distribution of MT2
~ Strategy to reduce BG ~
T–
decays into t + AH with 100 % branching ratio
H
1
H
2Slide36
“MT2 variable” is a powerful tool to determine m
T+
and mAH, which is defined by
with being the postulated AH mass. Then, the end point of MT2 distribution is~ Results (Point 2) ~~ Cut used in the analysis ~~ Discussion ~
T
–
pair production at the LHC0
100200Slide37
End-point of the distribution of M
T2 is determined by a combination of m
T+ , mAH, and the postulate mass . By looking at the position of the end-point with an appropriate value of , it is possible to get information of mAH & mT+!
We have also checked that there is no contamination of the BG around End-point!~ Results (Point 2) ~~ Conclusion ~~ Accuracy MT2(max) determination ~ Using the distribution of the MT2 with , the upper end-point will be determined with 10-20 GeV accuracy (at Point 2)!T– pair production at the LHCWith the use of quadratic function to estimate the end-point,
using
using
when . Theoretically, the end-point is 664 GeV.