recent results on dark matter searches at the...

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


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


Marta Felcini 4

CMS

ATLAS

LHC

ALICE

LHCb

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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

Standard Model Measurements


Marta Felcini

1 pb

1 fb

6

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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


Marta Felcini

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DM Searches @ LHC


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

DM production inSUSY Decays

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SUSY Chargino/Neutralino


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

http://arxiv.org/abs/arXiv:1801.01846

https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CombinedSummaryPlots/SUSY/

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SUSY Long Lived Particles


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


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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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


Marta Felcini

JHEP 01 (2018) 126mono-jet mono-photon Eur. Phys. J. C 77 (2017) 393

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https://link.springer.com/article/10.1007/JHEP01(2018)126

Mono-Jet/Mono-Photon


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

https://link.springer.com/article/10.1007/JHEP01(2018)126

Mono-jet/V(W,Z→jj)


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)


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


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

http://cds.cern.ch/record/2308271


Resonance Searches: Dileptons


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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https://arxiv.org/abs/1707.02424



Marta Felcini

arXiv:1803.06292



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Marta Felcini

JHEP 1710 (2017) 182 arXiv:1803.06292



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


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


Marta Felcini

Resonance

Searches

Mono-X

Searches

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DM Constraints – MonoX + Dijets, gl =0


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


Marta Felcini 28

Axial VectorMediator, Dirac DM, gDM = 1, gq = 0.25, gl = 0

DM Constraints, MonoX + Dijets, gl =0


Marta Felcini 29

Vector Mediator, Dirac DM, gDM = 1, gq = 0.25, gl = 0

DM Constraints, MonoX + Dijets + Dilepton


Marta Felcini 30

Axial VectorMediator, Dirac DM, gDM = 1 gq = 0.1gl = 0.1


Marta Felcini 31

Vector Mediator, Dirac DM, gDM = 1 gq = 0.1gl = 0.01

DM production in125 GeV Higgs Boson Decays

125 GeV Higgs Invisible Decays


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


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



https://project-hl-lhc-industry.web.cern.ch/content/project-schedule

Summary


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...


“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

recent results on dark matter searches at the...

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