Recent Results on DARK MATTER SEARCHES
AT THE LHCMarta Felcini
University College Dublin
on behalf of the ATLAS and CMS Collaborations
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Dark Matter SearchesDifferent approaches needed to discover the exact nature of particle DM
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
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LHC vs DM ID / DD Experiments
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
The LHC experiments aim to
probe SM – DM particle
interactions at the (terrestrial)
energy frontier (13-14 TeV)
measure the properties of
the DM candidate particles
(once detected)
develop methods to enhance the
complementarity with direct and
indirect DM searchesLHC experiments
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Large Hadron Collider Experiments
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini 4
CMS
ATLAS
LHC
ALICE
LHCb
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Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
Results from ATLAS and CMSLHC Run 2 pp collisions @ 13 TeV
Year Int. Lum. per exp.t
DMSearches
2015+20162017
up to ~40 fb-1up to ~50 fb-1
published ongoing
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Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
DM Detection If Dark Matter is composed of:
Particles
Weakly Interacting
Stable
→ leave the detector undetected
Momentum imbalance
Missing Tranverse
Momentum
PTmissaccompanied by one or
more visible objects
- triggering -
jets, leptons, photons
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Models for DM Production at Colliders
Effective
Field
Theories
SUSY
UED
Little
Higgs
UV
complete
Models
Z’
Higgs
portal
Simplified
Models
Increasing complexity THEORETICAL
MODELS
PHENOMENOLOGY Increasing complexity
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
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DM Searches @ LHC
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
Pair production
via Mediators
DM + Mono X
DM + Higgs
DM + tt / bb
125 GeV Higgs boson decay
SUSY decays
Mediators
also searched for
as resonances
decaying to
visible final states
PTmiss
DM
Production
discussed in this talk
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SUSY Chargino/Neutralino
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
Searches in the framework of
natural SUSY models with light EW gauginos
arXiv:1801.01846
Search for
Chargino
decaying to
LSP+SM
particles Neutralino Compressed Mass Spectrum
ATLAS Supersymmetry Summary plots
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SUSY Long Lived Particles
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
LLPs in many other BSM scenarios
GMSB SUSY, freeze-in DM, dark sector
→ LLP searches: extended research frontier
chargino nearly mass-degenerate
with a stable neutralino.
long-lived gluinos decaying to a
stable neutralino and a qq pair
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pMSSMConstraints
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
pMSSM11 preferred
mass ranges for SUSY particles
Lightest neutralino < 1 TeV
EW-ino compressed mass spectra
→ Long lived particles
Preferred region in the
direct detection plane
cross -section vs χ0 mass
arXiv:1710.11091
Example: constraints on
phenomenological MSSM models
with 11 parameters, including
13 TeV LHC searches results
Direct DM Pair production via Mediators
Mono-X and Resonances Searches
DM Constraints in Simplified Models
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Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
DM particle = Dirac fermion
DM-SM Mediator
spin 1 (axial-)vector, spin 0 (pseudo-)scalar
decay to SM pair or DM pair, min. decay width
accompanied by ISR = QCD parton,γ, W, Z, h
(pseudo-)scalar
mediator with heavy
flavour pair
s-channel (pseudo-) scalar mediators-channel, (axial-) vector mediator
s-channel mediator
→ mono-X
→ resonances
DM simplified models: examples
Parameters (values used in results):
Mmed mediator mass, mᵪ DM mass
gᵪ (1.0) mediator-DM coupling
gq (0.25 / 0.1) mediator-quark coupling
gl (0 / 0.01 / 0.10) mediator-lepton coupling
LHC DM Forum
arXiv:1507.00966
arXiv:1603.04156
arXiv:1703.05703
Mono-Jet/Mono-Photon
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
JHEP 01 (2018) 126mono-jet mono-photon Eur. Phys. J. C 77 (2017) 393
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Mono-Jet/Mono-Photon
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
JHEP 01 (2018) 126mono-jet mono-photon Eur. Phys. J. C 77 (2017) 393
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Axial Vector Mediator, Dirac Fermion DM,gq = 0.25, gDM = 1 → excluded up to mmed ~ 1.6 TeV mDM ~ 700 GeV
Axial Vector Mediator, Dirac Fermion DM,gq = 0.25, gDM = 1 → excluded up to mmed ~ 1.2 TeV mDM ~ 350 GeV
Mono-jet/V(W,Z→jj)
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini 18
arXiv:1712.0234Search for events
with
large PTmiss
at least one
energetic jet
(narrow or
fat),
veto other
objects
Data-driven
background
estimation
Likelihood fit
on control
regions
Mono-jet Mono-V(jj)
Mono-jet/V(W,Z→jj)
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
Vector Mediator Dirac DMgq = 0.25gDM = 1
excluded up to mmed ~ 1.8 TeVmDM ~ 700 GeV
Scalar Med.
95%CL limit
on σ / σth for
mDM=1 GeVgq = 1? gDM = 1
No constraint
In the plane
mmed–mDM
Axial Mediator Dirac DMgq = 0.25gDM = 1
excluded up to mmed ~ 1.75 TeVmDM ~ 500 GeV
Pseudo-scalarMediatorDirac DMgq = 1gDM = 1
excluded up to mmed ~ 430 GeV mDM ~ 160 GeV
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arXiv:1712.0234
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Mono-Higgs Searches
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
Z‘ Baryonic modelZ'-2HDM model
h → ττh → bb
Z'-2HDM models: excluded up to
MZ‘ ~ 2.6 TeV, mA ~0.6 TeV
CMS-PAS-EXO-16-055 Phys. Rev. Lett. 119 (2017) 181804
Baryonic Z' models: excluded up to
MZ‘ ~ 815 GeV for m DM = 1 GeV
March 2018
h → γγ
Resonance Searches: Dileptons
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
JHEP 1710 (2017) 182
Search in di-lepton (ee or μμ) mass distribution
Search for Z’ vector bosons and for gravitons
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Resonance Searches: Dileptons
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
arXiv:1803.06292
Search in di-lepton (ee or μμ) mass distribution
Search for Z’ vector bosons and for gravitons
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Resonance Searches: Dileptons
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
JHEP 1710 (2017) 182 arXiv:1803.06292
Search in di-lepton (ee or μμ) mass distribution
Search for Z’ vector bosons and for gravitons
Z’ lower limits ranging
from 3.8 to 4.5 TeV
Generic resonance upper limit on σ⋅BR for different resonance width
innterpreted in simplified models to set constraints on mmed and mDM (see next)
Lightest KK Graviton in RS ED model
excluded for masses 2.1 to 4.25 TeV
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Resonance Searches: Dijets
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
Phys.Rev. D96 (2017) no.5, 052004
jet mass using a jet sub-structure techniques.
JHEP 1801 (2018) 097
Search for LOW MASS narrow
resonances: Z’ → qq + ISR
Signal: boosted qq identified by
large-R jet w jet sub structure
Search for HIGH MASS
resonances: Z’ → qq
using dijet mass and
angular distributions
dijet mass
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Resonance Searches: Dijets
Also NEW from ATLAS:Light dijet
resonance search: arXiv:1801.08769:
JHEP 1801 (2018) 097 Phys.Rev. D96 (2017) no.5, 052004
Resonance searches set upper limits on
the coupilng gq ranging from 0.06 to 0.25
for MZ in the range 50 GeV to 3.5 TeV
Search for LOW MASS narrow
resonances: Z’ → qq + ISR
Signal: boosted qq identified by
large-R jet w jet sub structure
Search for HIGH MASS
resonances: Z’ → qq
using dijet mass and
angular distributions
DM Constraints – MonoX + Dijets, gl =0
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
Resonance
Searches
Mono-X
Searches
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DM Constraints – MonoX + Dijets, gl =0
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
Resonance
Searches
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Axial Vector Mediator Dirac DM, gDM = 1, gq = 0.25, gl = 0
DM Constraints, MonoX + Dijets, gl =0
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini 28
Axial VectorMediator, Dirac DM, gDM = 1, gq = 0.25, gl = 0
DM Constraints, MonoX + Dijets, gl =0
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini 29
Vector Mediator, Dirac DM, gDM = 1, gq = 0.25, gl = 0
DM Constraints, MonoX + Dijets + Dilepton
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini 30
Axial VectorMediator, Dirac DM, gDM = 1 gq = 0.1gl = 0.1
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini 31
Vector Mediator, Dirac DM, gDM = 1 gq = 0.1gl = 0.01
125 GeV Higgs Invisible Decays
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
VBF
qqH
Z(W) H
ggH
Observed (expected) upper limit of 0.24 (018)
on the Higgs invisible branching fraction
Processes searched for
March 2018
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CMS PAS HIG-17-023
125 GeV Higgs Invisible Decays
Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
CMS PAS HIG-17-023
upper limit on the Higgs
invisible branching fraction
interpreted in the context of
Higgs-portal DM models
upper bounds on the spin-
independent DM-nucleon
scattering cross section.
Most stringent constraints on
fermion (scalar) DM particles
with masses ≤ 20 (7) GeV
Higgs invisible decay search
covers effectively
the DM mass range < mH / 2
March 2018
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LHC Prospects
35Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
Discovery
arXiv:1712.04793JHEP 1501 (2015) 037
HILumiLHC Schedule
Discovery
150 fb-1 300 fb-1 3000 fb-1
13 TeV 14 TeV 14 TeV
Summary
36Moriond Cosmology 2018 March 17-24, 2018
Marta Felcini
The LHC experiments aim to probe SM – DM interactions and measure DM particle
properties at the (terrestrial) energy frontier of 13-14 TeV
complementarity with direct and indirect DM searches
LHC@13 TeV data collected so far ~3% of LHC+HiLumi LHC Luminosity @14 TeV.
Several avenues are explored searching for DM particles at the LHC in
decays of heavier particles, eg SUSY particles
direct DM pair production via mediators - mediator searched for as qq, ll resonances
invisible decays of the 125 GeV Higgs boson
Constraints have been set in many scenarios:
SUSY minimal models: mχ between ~100 GeV and ~1 TeV preferred;
Simplified models: mono X searches: depending on model parameter choice, can set
competitive σnDM limits for mDM up to ~300 GeV - more aggressive when including
resonance searches – coverage mDM<~10 GeV complementary to DD experiments
125 GeV H invisible decay search: competitve constraints for mDM < 62.5 GeV
most stringent constraints for mDM < 20 (7) GeV for fermion (scalar) DM particle;
The search for DM particles continues… it turned out to be more complex than we had
imagined;;; more surprises and discoveries await in the dark …
In the dark, discovery awaits...
37Moriond Cosmology 2018 March 17-24, 2018
“We have peered into a
new world and have
seen that it is more
mysterious and more
complex than we had
imagined. Still more
mysteries of the universe
remain hidden. Their
discovery awaits the
adventurous scientists
of the future.
I like it this way.”
Vera Rubin
Marta Felcini