Transcript Collider Constraints on Low Mass Dark Matter

Collider Constraints on Low
Mass Dark Matter
Haipeng An
University of Maryland
In collaboration with Xiangdong Ji and Liantao Wang
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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
Transverse
_
p (p)
Longitudinal
p
Cannot be detected!
The transverse momentum (pT) is conserved.
The signal is missing transverse momentum (MET).
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Relevant searches with MET
 Tevatron Constraints
pp
MET + Mono-jet
CDF Collaboration, PRL 101, 181602, 2008.
Yang Bai, Patrick Fox, Roni Harnik 1005.3797.
Goodman, Ibe, Rajaraman,
Shepherd, Tait, Yu 1005.1286, 1008.1783;
 LEP constraints
e+ e-
MET + Mono-photon
L3 Collaboration, Phys. Lett. B 587, 16, 2004.
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 Constraints
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
Jean-Francois Fortin, Tim M.P. Tait 1103.3289
Effective
operator
If the mass of the intermediate particle is around a few
hundred GeV, the interaction cannot be described by a
contact local operator.
Mediator:
vector boson, scalar boson, …
Dark matter: spinor, scalar, …
Interaction:
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vector-like, dipole-like, …
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Z’ model
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.
μ
μ
μ
μ
L = Z ' μ [q (g Z ' γ + g Z '5 γ γ 5 )q + χ (g D γ + g D 5 γ γ 5 )χ ].
g Z ' , g Z '5 , g D , g D 5 , M Z ' , M D
0
0
2
σ SI =
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2
2
2
2
3 g Z' g D M N M D
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π M Z ' (M N + M D )
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From Mediator to Contact
Interaction
pp
q
MET + Mono-jet
gZ’=gD , gZ’/MZ’ = 400 GeV
q
χ
Z'
2.0
Z'
2 M D < M Z' <
χ
1.5
sˆ , 2-body
pb
_
q
χ
Contact
interaction
_
q
χ
g
g
1.0
____________ M
D
50 GeV
____________ M
D
150 GeV
Width
----------
MD
50 GeV Contact Interaction
----------
MD
150 GeV Contact Interaction
600
800
1000 1200 1400
0.5
MZ’ < 2MD , 3-body final state
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0
200
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MZ ' GeV
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Outline
 Motivation
 From Mediator to Contact Interaction
 Current Collider Constraints
 LHC Reach
 Summary
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Collider constraint is stronger
than direct detection.
Tevatron Constraint
MZ’=100 GeV
MZ’=300 GeV
MZ’=700 GeV
MZ’=1500 GeV
No axial
couplings;
gZ’=gD;
gZ’5=0;
gD5=0.
Xenon100 11 days
New Xenon100
CalcHEP2.5.7
CoGeNT
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Tevatron + LHC
CMS
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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
pp
Missing ET + Monojet
Missing ET > 500 GeV, 100 fb-1 luminosity.
Vacavant and Hinchliffe, J. Phys. G 27 (2001) 1839-1850
SM background ≈ 20000.
S>5 B
Shepherd, Tait, Yu 1005.1286, 1008.1783
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LHC Reach
gZ’=gD
gD=1
gZ’=gD
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SI
cm2
LHC Reach
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38
10
39
10
40
10
41
10
42
MD = 20 GeV
MD = 5 GeV
MD = 1 GeV
Z’ on shell
0
500
Z’ off shell
1000
1500
2000
2500
MZ' GeV
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Normalized Number of Events
Determine the Mass of Z’
1
300 GeV
500 GeV
2000 GeV
700 GeV
1100 GeV
1500 GeV
0.1
0.01
0.001
SM background
Vacavant and Hinchliffe,
10
4
J. Phys. G 27 (2001) 1839
600
800 1000 1200 1400 1600 1800 2000
JetPT GeV
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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
B-xL model
gZ’ = gD
Di-lepton
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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.
V2 ~ 10-6
SIMD
CalcHEP2.5.6
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