Dark Matter Searches at CMS - X - CERN Indico

DM

 DM

 Dark Matter Searches
 at CMS
 X
 VARUN SHARMAvarun.sharma@cern.ch
 UNIVERSITY OF WISCONSIN – MADISON, USA
 ON BEHALF OF THE CMS COLLABORATION

Virtual World

New physics signature

✫ There is overwhelming evidence for the existence of dark matter from
 its gravitational effects.

✫ Several models with various type of interactions

✫ No observation in laboratory yet!

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Dark Matter
• Favourite collider candidate: WIMP

• Weakly interacting, massive, stable

 General collider strategy
 X = , W, Z, H, g, t Indirect Detection

 Direct Detection
 M ET Collider
Non-interacting particles cause momentum imbalance in the
transverse plane of the beam
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Simplified Dark Matter Models
 • Dark matter production in pp collisions described using “simplified models"
 • Capture the essential features of a variety of DM signals through a minimal set of
 parameters

 ü s – channel mediators LHC DM Forum
 arXiv:1507.00966
 spin – 0 spin – 1

 Parameters:
 - Spin/Parity of mediator
 - Mediator mass (Mmed)
 ü t – channel mediators - DM Mass (MDM)
 - Mediator coupling to DM (gDM)
 - Mediator coupling to quarks (gq)

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http://cms-results.web.cern.ch/cms-results/public-results/publications

 SM interactions are understood pretty
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 well
 May 25-30, 2020 5

Wide range of Searches CMS DM Results
 CMS Public Results

A rich and diverse DM search program to exploit the full potential of the LHC
experiment
 Analysis Document Luminosity
 Mono-jet PRD 97 (2018) 092005 36 fb-1
 Mono-Z(ll) EPJC 78 (2018) 291 36 fb-1
 Mono-photon JHEP 02 (2019) 074 36 fb-1
 Mono-LQ PLB 795 (2019) 76 77 fb-1
 DM+bb EPJC 77 (2017) 845 2.2 fb-1
 Mono-top (had) JHEP 06 (2018) 027 36 fb-1
 DM+single top JHEP 03 (2019) 141 36 fb-1
 DM+ tt (combined) PRL 122 (2019) 011803 36 fb-1
 Mono-H(bb) EPJC 79 (2019) 280 36 fb-1

 Mono-H ( , ) JHEP 09 (2018) 172 36 fb-1
 JHEP 09 (2018) 046
 Mono-H (combined) JHEP 03 (2020) 025 36 fb-1 Boosted dijet PRD (2019) 112007 77 fb-1
 H to dark photons JHEP 10 (2019) 139 137 fb-1 Dijet w/ btag PRL 120 (2018) 201801 20 fb-1 (8 TeV)
 H to invisibles PLB 793 (2019) 520 63 fb-1 Dijet w/ ISR PLB 805 (2020) 135448 18 fb-1 (scouting)
 dijet JHEP 08 (2018) 130 36 - 137 fb-1
 Only a personal selection JHEP 05 (2020) 033

 of recent results 4 top quarks EPJC 80 (2020) 75 137 fb-1

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Mono – jet Mono – photon Mono – V (W/Z)

 PRD 97 (2018) 092005 JHEP 02 (2019) 074 PRD 97 (2018) 092005

 Mono-Z (ll):
 EPJC 78 (2018) 291
Probe ISR based MET+ X searches

Signature: large MET and ≥1 high-pT jet/vector boson/photon

 Spin – 1 Mediator:
 Simplified and Extended Sector
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Mono-Jet/V Search PRD 97 (2018) 092005

Generally most sensitive mono-X search
 Backgrounds:
Selection: • Z( )/W(l ) +jets, top, diboson, multijet
• At least one high-pT central jet • Dominant backgrounds normalized in
• Large MET (> 250 GeV) control regions

• Veto leptons & isolated tracks Signal region ⇒ high MET
 Mono-V:
 • Jet radius: 0.8
 • pT (j) > 250 GeV

 Mono-Jet
 • Jet radius: 0.4
 • pT (j) > 100 GeV
 • Not passing mono-V
 selection

Final results:
ü combined SR+CR fit
ü Sys Unc as nuisance parameters

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Mono-Jet/V Interpretations PRD 97 (2018) 092005

 Exclusion limits at
 90%CL in the
 mDM vs. σSI/SD plane
 for vector (left) &
 axial-vector (right)
 mediator models

 Exclusion limits at
 95%CL on
 μ = σ/σth in the
 mmed – mDM plane

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Spin-1 Mediator Results CMS DM Summary Plot

 95% CL observed and expected exclusion regions in mmed – mDM lane for di-jet searches
 and different MET based DM searches from CMS in the lepto-phobic Vector model.

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Spin-1 Mediator Results CMS DM Summary Plot

 Mono-X searches not sensitive to off-shell region (i.e. mDM > mmed/2)
 • Cross section is highly suppressed

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Spin-1 Mediator Results CMS DM Summary Plot

 Constraints come on Z’ from visible and invisible decays
 • Boosted dijet, dijet, tt, bb resonances

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Spin-1 Mediator Results CMS DM Summary Plot

 95% CL observed and expected exclusion regions in mMed-mDM plane for different MET
 based DM searches from CMS in the lepto-phobic Axial-vector model.
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DM + t(tt) Mono – jet Mono – Z

 JHEP 03 (2019) 141 PRD 97 (2018) 092005 EPJC 78 (2018) 291
 PRL 122 (2019) 011803
 Mono-V (Had):
 JHEP 06 (2018) 027 PRD 97 (2018) 092005

• Interaction between spin-0 mediator and quarks required to have the SM Yukawa structure
 (Minimal Flavor Violation)
• Coupling to quarks proportional to the quark mass (like the SM Higgs boson)

 Spin – 0 Mediator:
 Simplified Models
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DM + t(tt) Search
Spin-0 mediator couples preferentially to the top
quark

Event Categorization: #leptons, #b-jets, #forward jets Backgrounds:
 • tt, V + jets
0-leptons JHEP 03 (2019) 141 • Dominant backgrounds
• Veto leptons normalized in control regions
• ≥ 3 jets
 • +0 or ≥ 1 forward jets
• =1, ≥ 2 b-jets
• MET > 250 GeV

1-leptons
• Veto leptons
• ≥ 3 jets
 • +0 or ≥ 1 forward jets
• =1, ≥ 2 b-jets
• MET > 160 GeV

Final results:
ü combined SR+CR fit
ü Sys Unc as nuisance
 parameters
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DM + t(tt) Results
 JHEP 03 (2019) 141

 The expected and observed 95%
 CL limits on the DM production
 cross sections

 First Results @ LHC
 for DM+t(tt) in scaler & pseudo
 scalar interactions

 EPJC 80 (2020) 75

 Recover sensitivity: Visible decays

 Exclusion regions at 95% CL
 in the plane of
 m m vs mHmH (left)
 or mAmA (right).

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t-channel Interpretations
 JHEP 06 (2018) 027
 JHEP 1501 (2015) 017

 Mono-top: Resonant Model
 Mediator – 2/3 charged, colored, spin-0
 Mono-jet: Fermion Portal model
PRD 97 (2018) 092005

 (color triplet mediator) Results re-interpreted in t-channel

 The 95%CL expected (black dashed line) and
 observed (red solid line) upper limits on μ=σ/σth in Upper limits at 95% CL on the mass of the
 the context of the fermion portal DM model, for scalar particle φ in the resonant model
 Dirac DM particles
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Mono – H
 Various Higgs decays
 Mono – H (bb)
 
 0.2% 12% medium boost Mono – H (inv)
WW 21% 58%
 3% 6% bb

 ZZ large boost
 
 PLB 793 (2019) 520
 JHEP 03 (2020) 025 [combined] EPJC 79 (2019) 280
 JHEP 09 (2018) 046 [ , ] JHEP 09 (2018) 172

Signature: Large MET + one Higgs boson candidate

 Higgs Boson:
 Extended sector & invisible decays
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Mono – Higgs Combined JHEP 03 (2020) 025
 EPJC 79 (2019) 280

 Z’ Baryonic Z’ 2HDM
 (non-resonant) (resonant) 2HDM + a

 0.1 < mZ’ < 1.6 TeV for 0.6 < mZ’ < 3.2 TeV for 0.5 < mA < 0.9 TeV for
 m = 300 GeV mA = 300 GeV ma = 150 GeV

 med. boost
med. boost large boost

 Upper limits at 95% CL on the observed and expected σ/σth for the baryonic

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Higgs Invisible Results Phys. Lett. B 793 (2019) 520

 Interpretations: Higgs portal models of Dark Model interactions

 Observed 95% CL upper limits on (σ /σSM ) B Constraints on the spin-independent DM-
 (H → inv), whose production xs varies as a nucleon interaction cross section
 function of coupling multipiers

The observed 90% CL upper limit of B(H → inv) < 0.16 is interpreted in terms of Higgs-portal
models of dark matter (DM) interactions

Limits provides constraints on fermion (scalar) DM particles with masses smaller than about 18 (7) GeV
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Higgs Invisible Results Phys. Lett. B 793 (2019) 520

 Interpretations: Higgs portal models of Dark Model interactions

 More detail in Talk by
 Douglas Michael Schaefer [NEXT]

 Observed 95% CL upper limits on (σ /σSM ) B Constraints on the spin-independent DM-
 (H → inv), whose production xs varies as a nucleon interaction cross section
 function of coupling multipiers

The observed 90% CL upper limit of B(H → inv) < 0.16 is interpreted in terms of Higgs-portal
models of dark matter (DM) interactions

Limits provides constraints on fermion (scalar) DM particles with masses smaller than about 18 (7) GeV
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Resonance constraint on DM CMS DM Summary Plot

Indirectly constraining DM models
• Constraints on couplings
• Vary of model parameter and assumptions

 Constraints on quark coupling
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Resonance constraint on DM CMS DM Summary Plot

Indirectly constraining DM models
More detail on Friday by
• Constraints on couplings
Mariia
• VarySavina
 of model[Joint BSMand
 parameter Session]
 assumptions Comparison with results
 from other experiments

 Constraints on quark coupling
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Summary
• A rich and diverse dark matter search program at CMS

• No excess yet
 • New ideas, brain-storming to continue

• Mostly only 2016 (36 fb-1) data analysed so far for 13 TeV

• Many new results with full 13 TeV data (137 fb-1) expected in
 next months
 • Several improvements and new interpretations foreseen

 Stay tuned for more updated results!

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CMS DM Results
 CMS Public Results

 Thank You
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BACK - UP

Spin – 0 Mediator Results CMS DM Summary Plot

 95% CL observed (full-line) and expected (dashed-line) exclusion limits for the
 Scalar (left) and Pseudo-scalar (right) model as a function of mmed for different
 MET based DM searches from CMS.

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Higgs Invisible Phys. Lett. B 793 (2019) 520

 Dark matter
 candidates

 Higgs production via associated production &
 gg-fusion also considered

• A lot still unknow about 125GeV Higgs boson
 • SM may couple to DM via H(125)

• Search exploits large mjj and |∆ jj| that
 characterize VBF higgs production
 Fit (including SR) to mjj distribution
• Major background (~95%):
 to extract signal
 • Z( )+jets and W(ℓ )+jets

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Higgs Invisible Results PLB 793 (2019) 520
 CMS PAS HIG-18-008

Upper limit on B(H → inv) att 95% CL, assuming SM production rates for the
Higgs boson and a Higgs boson mass of 125.09 GeV
 Upper bounds using ttH
 production

 All Channels combined Grand combination
 @ 13 TeV (36 fb-1)

 Combined 7+8+13 TeV: 0.19 (0.15)
 BR(H → inv) < 0.46 (0.48)
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