taking a razor to dark matter parameter space (at the lhc) chiu-tien yu (uw-madison/fermilab) with...

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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Looking for DM

DM

DM

DM SM

SM

collider

indirect

direct

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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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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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DM

DM SM

SM

collider

indirect

DM

DM SM

SM

indirect

direct

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No low energy

threshold at colliders

does fine with spin-dependence

complementary to direct detection experiments

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DM

DMSM

SM

Dark Matter at Colliders

6


something

DM

DMSM

SM


6


something

DM

DMSM

SM


We can use monojet (or monophoton) searches to place limits on the direct detection plane.

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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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Effective Field Theory

Spin-independent, vector exchange

Spin-dependent, axial-vector exchange

Spin-independent, gluon operator

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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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dominant background dominant signalinitial-state initial-state

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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


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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...that caught the attention of the experimental community.

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something

DM

DMSM

SM


Monojets do ok, but can we do better?

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something

DM

DMSM

SM


jets are cheap at the LHC ($)

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somethings

DM

DMSM

SM



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DM

DMSM

SM



...and give you more handles on the data.Plus, complementary to monojets. ($$$)

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somethings


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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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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Enter, the RazorZ+jets 100 GeV DM

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Enter, the RazorZ+jets 100 GeV DM

signal region

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800 pb-1

LHC7

Razor results

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800 pb-1

LHC7

Razor results

best limits at low mass best limits everywhere

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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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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


backups


light mediators

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taking a razor to dark matter parameter space (at the lhc) chiu-tien yu (uw-madison/fermilab) with...

Documents

colliders6somethingdark

somethingsdark matter

light majorana dark

dark matter parameter

dark matterphys

direct detection searches

vector exchangespindependent

direct detection crosssection