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Taking a Razor to Dark Matter
Parameter Space (at the LHC)
Chiu-Tien Yu (UW-Madison/Fermilab)
with Paddy Fox, Roni Harnik, and Reinard PrimulandoarXiv: 1203.1662
May 8, 2012 Phenomenology 2012 Symposium
Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
There is a strong case for the existence of dark matter
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
Looking for DM
DM
DM
DM SM
SM
collider
indirect
direct
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
Direct Detection
arXiv:1104.2549
impressive work, still has a lot of unresolved issues
(PRL, 106:021303, 2011)
arXiv:1104.2549
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
Direct Detection
arXiv:1104.2549
impressive work, still has a lot of unresolved issues
backgrounds, calibration, local DM density, ...
(PRL, 106:021303, 2011)
velocity suppression recoil energy
threshold
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
DM
DM SM
SM
collider
indirect
DM
DM SM
SM
indirect
direct
4
Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
No low energy
threshold at colliders
does fine with spin-dependence
complementary to direct detection experiments
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
DM
DMSM
SM
Dark Matter at Colliders
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
something
DM
DMSM
SM
Dark Matter at Colliders
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
something
DM
DMSM
SM
Dark Matter at Colliders
We can use monojet (or monophoton) searches to place limits on the direct detection plane.
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
3 simple steps to finding DM
•Assume that an effective field theory is valid at the collider -- consider contact operators
•Find the collider limit on the scale Lambda by looking for an excess of events
•Translate the Lambda bound into a direct detection cross-section
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
Effective Field Theory
Spin-independent, vector exchange
Spin-dependent, axial-vector exchange
Spin-independent, gluon operator
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
Effective Field Theory
Spin-independent, vector exchange
Spin-dependent, axial-vector exchange
Spin-independent, gluon operator
Collider searches can tell you something about these.
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
dominant background dominant signalinitial-state initial-state
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
dominant background dominant signalinitial-state initial-state
Z preferentially emitted with
low pT, so jet(s) are as well.
Jet(s) distributed isotropically
Exploit this difference in kinematics*9
Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012 10
Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
Some great monojet/photon theory papers...
Fermilab clan: P. Fox, J. Kopp, R. Harnik, Y. TsaiMissing Energy Signatures of Dark Matter at the
LHCarXiv:1109.4398LEP Shines Light on Dark MatterPhys. Rev. D84, 014028 (2011).Irvine
contingent: J. Goodman, M. Ibe, A. Rajaraman, W. Shepherd,T. M. P. Tait, A. M. Wijangco, and H. -B.
YuLHC Bounds on Interactions of Dark MatterarXiv:1108.1196Constraints on Dark Matter
from CollidersPhys. Rev. D82, 116010 (2010)Constraints on Light Majorana dark Matter from
CollidersPhys. Lett. B695, 185-188 (2011)
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
...that caught the attention of the experimental community.
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
something
DM
DMSM
SM
Dark Matter at Colliders
Monojets do ok, but can we do better?
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
something
DM
DMSM
SM
Dark Matter at Colliders
jets are cheap at the LHC ($)
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
somethings
DM
DMSM
SM
Dark Matter at Colliders
jets are cheap at the LHC ($)
13
Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
DM
DMSM
SM
Dark Matter at Colliders
jets are cheap at the LHC ($)
...and give you more handles on the data.Plus, complementary to monojets. ($$$)
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somethings
Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
Enter, the Razor•CMS analysis for SUSY using 2D
distribution of two kinematic variables.
•Takes multijet events and puts them into a di-“megajet” topology -- keep more events.
•Variables follow simple exponential distributions -- data-driven analysis.
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
Enter, the Razor
}estimate the scale of the event
}ratio of MET to visible
low R
jet 1 jet 2
high R
jet 1jet 2
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
Enter, the RazorZ+jets 100 GeV DM
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
Enter, the RazorZ+jets 100 GeV DM
signal region
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
800 pb-1
LHC7
Razor results
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
800 pb-1
LHC7
Razor results
best limits at low mass best limits everywhere
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
Conclusion• Collider searches for DM give
complementary (and competitive) bounds to direct detection searches.
• Current monojet/monophoton analyses from the Tevatron and LHC give the best limits for light DM and for spin-dependent DM.
• Inclusive jet + MET searches such as Razor will provide even more discriminating power.
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Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
Conclusion• Collider searches for DM give
complementary (and competitive) bounds to direct detection searches.
• Current monojet/monophoton analyses from the Tevatron and LHC give the best limits for light DM and for spin-dependent DM.
• Inclusive jet + MET searches such as Razor will provide even more discriminating power.
Watch for this!18
Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
backups
Chiu-Tien Yu (UW-Madison/Fermilab) Pheno2012 May 8, 2012
light mediators
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