5/9/2011 PHENO 2011 1
Collider Constraints on Low Mass Dark Matter
Haipeng AnUniversity of Maryland
In collaboration with Xiangdong Ji and Liantao Wang
5/9/2011 PHENO 2011 2
Outline Motivation
From Mediator to Contact Interaction
Current Collider Constraint
LHC Reach
Summary
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Dark Matter Direct Detection
15 GeV
5 GeV
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Observable
p p_ (p)
The transverse momentum (pT) is conserved.
The signal is missing transverse momentum (MET).
Cannot be detected!
Longitudinal
Transverse
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Relevant searches with MET Tevatron Constraints
LEP constraints
CDF Collaboration, PRL 101, 181602, 2008.
p p MET + Mono-jet
e+ e- MET + Mono-photon
L3 Collaboration, Phys. Lett. B 587, 16, 2004.
Yang Bai, Patrick Fox, Roni Harnik 1005.3797.Goodman, Ibe, Rajaraman, Shepherd, Tait, Yu 1005.1286, 1008.1783;
Patrick J. Fox, Roni Harnik, Joachim Kopp, Yuhsin Tsai 1103.0240
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Outline Motivation
From Mediator to Contact Interaction
Current Collider Constraint
LHC Reach
Summary
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Collider ConstraintsYang Bai, Patrick Fox, Roni Harnik 1005.3797.Goodman, Ibe, Rajaraman, Shepherd, Tait, Yu 1005.1286, 1008.1783;Patrick J. Fox, Roni Harnik, Joachim Kopp, Yuhsin Tsai 1103.0240Jean-Francois Fortin, Tim M.P. Tait 1103.3289
If the mass of the intermediate particle is around a few hundred GeV, the interaction cannot be described by a contact local operator.
Effective operator
Mediator: vector boson, scalar boson, …
Dark matter: spinor, scalar, …
Interaction: vector-like, dipole-like, …
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Z’ model
Z' Z'5 D D5 Z' Dg , g , g , g , M , M
μ μ μ μμ Z' Z'5 5 D D5 5L= Z' [q(g γ +g γ γ )q+ χ(g γ +g γ γ )χ].
1. Leptophobic vector boson (Z’) couples to SM quarks universally and dark matter particle.
2. Dark Matter particle is a Dirac spinor.
3. The coupling between Z’ and dark matter can be either vector-like.
2 2 2 2 2Z' D N D
SI 4 2Z' N D
3 g g M Mσ =
πM (M +M )
0 0
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____________ M D 50 G eV
____________ M D 150 G eV
- - - - - - - - - - M D 50 G eV Con tact In teract ion
- - - - - - - - - - M D 150 G eV Con tact In teract ion
0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0
0 .5
1 .0
1 .5
2 .0
M Z ' G eV
pb
From Mediator to Contact Interaction
gZ’=gD , gZ’/MZ’ = 400 GeV
MZ’ < 2MD , 3-body final state
χ
χ
Z'q
q_
g
ˆD Z'2M <M < s , 2-body
Z'
q
q_
g χ
χ
Contact interaction
p p MET + Mono-jet
Width
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Outline Motivation
From Mediator to Contact Interaction
Current Collider Constraints
LHC Reach
Summary
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Tevatron Constraint
Xenon100 11 days
New Xenon100
CoGeNT
No axial couplings;
gZ’=gD;
gZ’5=0;
gD5=0.
Collid
er
con
str
ain
t is
str
on
ger
than
dir
ect
dete
cti
on
.
MZ’=100 GeV
MZ’=300 GeV
MZ’=700 GeV
MZ’=1500 GeV
CalcHEP2.5.7
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Tevatron + LHC
CMS arXiv:1102.2020
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Outline Motivation
From Mediator to Contact Interaction
Current Collider Constraint
LHC Reach
Summary
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LHC Reach
S > 5 B
p p Missing ET + Monojet
Missing ET > 500 GeV, 100 fb-1 luminosity.Vacavant and Hinchliffe, J. Phys. G 27 (2001) 1839-1850
SM background ≈ 20000.Shepherd, Tait, Yu 1005.1286, 1008.1783
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LHC Reach
Xenon 100MZ’=500 GeV gZ’=gD
MZ’=3000 GeV gZ’=gD
MZ’=500 GeV gD=1
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LHC Reach
0 5 0 0 1 0 0 0 1 5 0 0 2 0 0 0 2 5 0 01 0 4 2
1 0 4 1
1 0 4 0
1 0 3 9
1 0 3 8
M Z ' G e V
SI
cm2 MD = 20 GeV
MD = 5 GeV
MD = 1 GeVZ’ on shell
Z’ off shell
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Determine the Mass of Z’
6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0 1 6 0 0 1 8 0 0 2 0 0 01 0 4
0 .0 0 1
0 .0 1
0 .1
1
J e tP T G e V Nor
mal
ized
Num
ber
ofEv
ents
SM background
300 GeV500 GeV
700 GeV1100 GeV
1500 GeV
2000 GeV
Vacavant and Hinchliffe,
J. Phys. G 27 (2001) 1839
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Determine the Mass of Z’
Bin[1]: 500 GeV < PT < 600 GeV;
Bin[2]: PT > 600 GeV.
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Summary Collider constraints are very important in the
case of low mass dark matter;
Tevatron constraints and LHC reach strongly depends on the mass of Z’;
The mass of Z’ can be determined from the distribution of jet transverse momentum.
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Backup: LEP constraint
Mono photon + MET
Di-lepton
B-xL model
gZ’ = gD
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Overview
Existence;
Dark;
Massive;
Stable;
Relic abundance
~ 25%;
Not identified yet.
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Tevatron Constraints on Direct Detection Cross section
gZ’5 = 0, gD = 0, MD = 5 GeV.
gD5 = 1g
D5 = 0.5
V2 ~ 10-6 SIMD
CalcHEP2.5.6
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