[PPT] - Techniques and Results of Neutral Long-Lived echniques and Results PowerPoint Presentation

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Techniques and Results of Neutral Long-Lived echniques and Results of Neutral Long-Lived Particle Sear Particle Searches in A ches in ATLAS and CMS in LHC Run 2 TLAS and CMS in LHC Run 2

Rencontres de Moriond, Electroweak Session Claudia-Elisabeth Wulz

Institute of High Energy Physics, Vienna For the ATLAS and CMS Collaborations La Thuile, 18 March 2019

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Sour Sources of neutral long-l ces of neutral long-lived part ived particles icles

Standard model (SM): neutral B, D and K mesons, neutrons, neutrinos Beyond standard model (BSM): plethora of different models

R-parity violating SUSY
Gauge-mediated SUSY breaking scenarios
Anomaly mediated SUSY breaking scenarios
Split SUSY
Stealth SUSY
Hidden valley scenarios
Dark QED (particularly dark photons)
Dark QCD (particularly dark hadrons)
Dark matter models
Left-right symmetric models (particularly heavy neutrinos)
Axion-like particles (ALPS)
Approximate symmetries
...

Conditions for models with long-lived particles (at least one)

Small phase space - nearly degenerate mass spectra
Small couplings
Highly virtual intermediate states

Green: covered in this talk

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Mot Motivat ivation to sear ion to search for new long-l ch for new long-lived part ived particles icles

Searches for new long-lived particles (cτ > 1 mm) ongoing for several years

ATLAS/CMS a priori designed/optimized for prompt particles, not new

LLP‘s

Clever ideas for triggering / data acquisition / reconstruction / analysis

have been and are being developed, in parallel with theory developments … but no signal observed so far!

Preparations for Run 3 and detector upgrades for HL-LHC have strong

focus on new LLP‘s

Figure by Kathryn Zurek

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Signatur Signature-driven sear e-driven searches ches

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dileptons ileptons, lepton-jets , lepton-jets mul multitrack itrack vert vertices ices mul multitrack itrack vert vertices ices in in muon muon system system trackless, trackless, low-EMF jets low-EMF jets emer emerging ging jets jets photons photons

Figure adapted from Heather Russell

Displaced decays

Displaced multitrack vertices
Displaced photons
Displaced jets
Emerging jets
Trackless jets, with low

electromagnetic energy fraction

Displaced dileptons and lepton-jets

Delayed decays and trapped stable particles

Particles stopped in detector
Particles trapped in detector,

e.g. magnetic monopoles

Out-of-time detection possible

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Chal Challenges lenges

Physics

Unusual fractions of electromagnetic / hadronic energies in calorimeters
Decays outside usual detectors, e.g. jets in muon system
Unusual, not yet known signatures

Trigger, reconstruction and data analysis

Inadequate triggers or triggers with low efficiency
Timing information not always available
Standard object reconstruction often inadequate
Secondary vertex finding algorithms not optimized
Interaction point constraint in triggering / reconstruction not usable
Systematic uncertainties need to be specially estimated
Simulation samples not readily available

Backgrounds

In-time and out-of-time pileup
Long-lived standard model hadrons (KL, b, …)
Cosmic rays
Accelerator-related backgrounds (beam halo, satellite bunches)
Electronic noise
Material interactions

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Specific techniques Specific techniques

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Trigger and data acquisition

Simple requirements, without saturating bandwidth
Trigger on prompt particles in associated production
Trigger on subsequent bunch crossings, or during gaps in bunch trains
Scouting: store only reduced event information, but at high rate
Parking: store full raw data, without immediate processing
Non-standard information, such as timing, added to event record

Reconstruction

Avoid that events get rejected at early stages of reconstruction -> check

initial basic requirements

Track reconstruction optimized for prompt particles -> need dedicated

tracking algorithms

Secondary vertices: b tagging algorithms extended to work better at

distances beyond 1 cm

Particle flow reconstruction (CMS) needs to be adapted
Electrons and taus need further development
Spike cleaning in calorimeters must be checked and adapted
Instrumental and non-collision backgrounds from data
Pileup can be useful for low-pT displaced tracks, e.g. from sexaquarks

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Displaced jets Displaced jets

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Signature

Jets with vertices displaced up to 55 cm from primary

vertex in transverse plane, reconstructed from energy deposits in calorimeter towers, with or without MET Dedicated displaced jet trigger

HT > 350 GeV
≥ 2 jets with pT > 40 GeV, IηI < 2
≤ 2 associated prompt tracks
≥ 1 associated displaced track

Background suppression

QCD multijets
Likelihood discriminant from track, jet and vertex

information

Displaced Di-Jet

Benchmark models and interpretations

Jet-jet model: pp -> XX, X -> qq (X = neutral scalar)
SUSY models with LLP

, e.g. GMSB model with long- lived gluino, decaying to gluon and gravitino (g -> g G) arXiV 1811.07991 CMS-EXO-18-007 ~ ~

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Displaced jets Displaced jets

Gluino masses up to 2300 GeV excluded for proper decay lengths between 20 and 110 mm

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1 10

2

10

3

10

4

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[mm] τ c

1 −

10 1 10

2

10

3

10

4

10

5

10

[fb] σ (13 TeV)

1

35.9 fb CMS

95% CL upper limits

Jet-Jet model

Observed Median expected = 50 GeV

X

m = 100 GeV

X

m = 300 GeV

X

m = 1000 GeV

X

m

arXiV: 1811.07991, CMS-EXO-18-007

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Delayed jets Delayed jets

CMS-EXO-19-001

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Jet timing in barrel ECAL

PbWO4 crystals with Si APDs
Time resolution ≈ 200 ps
Cells within ΔR < 0.4 of jet
tjet

jet defined by med

defined by median cel ian cell t l time ime Model assumption and dataset

GSMB SUSY model: g -> gG
Full Run 2 dataset: 137 fb-1

Trigger and signal selection

HLT trigger: MET > 120 GeV
MET + delayed calorimeter jet: 3 ns < tjet

jet < 20 ns

Particle flow not used for jet reconstruction due to non-standard tracker

component, calorimeter clustering only ~ ~

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20 − 15 − 10 − 5 − 5 10 15 20

(ns)

jet

t

1 −

10 1 10

2

10

3

10

4

10

5

10

6

10

2016 (35.5/fb) 2017 (41.8/fb) 2018 (55.2/fb) 20 − 15 − 10 − 5 − 5 10 15 20

(ns)

jet

t

1 −

10 1 10

2

10

3

10

4

10

5

10

6

10

7

10

2016 (35.5/fb) 2017 (41.8/fb) 2018 (55.2/fb)

Delayed jets Delayed jets

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Satellite bunches (example profile)

Backgrounds estimated from control regions with data

ECAL resolution tails
Direct APD hits
In-time and out-of-time pileup
Beam halo
Satellite bunches (2.5 ns steps)
Cosmic muon deposits in ECAL

Rejection of main backgrounds through jet cleaning

number of ECAL cells > 25
electromagnetic / total calorimeter energy fraction > 0.2
fraction of tracks associated to primary vertex < 1/12
RMS of tjet

Befor Before jet cleaning e jet cleaning After jet cleaning After jet cleaning

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Delayed jets Delayed jets

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Significantly extended reach in cτ compared to tracker based searches
Gluino masses up to 2500 GeV (2150 GeV) excluded for cτ of 1m (30 m)

2 4 6 8 10 12

(ns)

jet

t

5 −

10

4 −

10

3 −

10

2 −

10

1 −

10 1 10

2

10

3

10

4

10

Events/0.5 ns

Beam halo background Core and satellite backgrounds Cosmic background Observation = 1 m τ = 2400 GeV, c

g ~

GMSB m = 10 m τ = 2400 GeV, c

g ~

GMSB m = 30 m τ = 2400 GeV, c

g ~

GMSB m

CMS Preliminary = 13 TeV s

1

= 137 fb

int

L

2.5 3 3.5 4 4.5 5

/mm) τ (c

10

log

1000 1500 2000 2500 3000 3500

(GeV)

g ~

m

2 −

10

1 −

10 1 10

(fb) σ 95% CL upper limit on

2 −

10

1 −

10 1 10

(fb) σ 95% CL upper limit on

CMS Preliminary = 13 TeV s

1

= 137 fb

int

L

GMSB NLO+NLL exclusion G ~ g + → g ~ , g ~ g ~ → pp

95% CL observed σ 1 ± 95% CL expected median

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(jet, tracks)

min

R ∆

1 2 3 4 5

per-event BDT

T

High-E

0.1 0.2 0.3 0.4 0.5

0.0002 0.0004 0.0006 0.0008 0.001 0.0012 0.0014 0.0016 0.0018 0.002

∑

Selection

T

High-E )=(600,150) GeV

s

, m

Φ

(m

A B C D

ATLAS Simulation

=13 TeV s

Trackless jets - scalars decaying in calorimeters rackless jets - scalars decaying in calorimeters

EXOT-2017-025, arXiV 1902.03094 Models and dataset

Hidden-sector models
10.8 fb-1 and 33.0 fb-1 at √s = 13 TeV
cτ range few cm to tens of m

Signature and trigger

Displaced jets in HCAL or outer edge
f ECAL
At least 2 trackless and low-EMF jets -

CalRatio (CR) jets

dedicated low- and high-ET triggers

Analysis strategy and background

Machine learning techniques (neural

network to determine jet origin, BDT classifier for jets)

Backgrounds: mainly multijet and

beam-induced, estimated with ABCD method

arXiV: 1810.12602

C.-E. Wulz 12

A: signal region

mΦ = 600 GeV, ms = 150 GeV

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s proper decay length [m]

1 −

10 1 10

2

10

ss → Φ

B 95% CL Upper Limit on

4 −

10

3 −

10

2 −

10

1 −

10 1 10

2

10

3

10

4

10

5

10 ATLAS

= 13 TeV s = 25 GeV

s

= 125 GeV, m

Φ

m ]

1

CR limit [10.8 fb ]

1

MS1+MS2 limit [36.1 fb CR+(MS1+MS2) limit Obs. σ 1 ± Exp.

ss → H

B 100%

ss → H

B 10%

ss → H

B 1%

Trackless jets - scalars decaying in calorimeters rackless jets - scalars decaying in calorimeters

13

95% CL limits set on σ(ϕ) x B(ϕ→ss)

Mediator ϕ with mϕ = 125 GeV: ms between 5 and 55 GeV excluded for cτ between 5 cm and 5m, for B(ϕ→ss) = ) = 10% For mϕ = 400 GeV, mϕ = 600 GeV, and mϕ = 1000 GeV, σ(ϕ) × B(ϕ→ss) values > 0.1 pb excluded between 12 cm and 9 m, 7 cm and 20 m, and 4 cm and 35 m respectively, depending on ms

1 −

10 1 10 s proper decay length [m]

3 −

10

2 −

10

1 −

10 1 10

2

10

3

10

4

10

5

10

6

10

7

10

8

10 [pb]

ss → Φ

B × σ 95% CL Upper Limit on

1

= 13 TeV 33.0 fb s

bs. limit
exp. limit

σ 1 ± exp. σ 2 ± exp. = 150 GeV

s

= 600 GeV, m

Φ

Scaled Run 1 limit (8TeV) m

ATLAS

selection

T

= 150 GeV, high-E

s

= 600 GeV, m

Φ

m

Run I (scaled) mΦ = 600 GeV, ms = 150 GeV

C.-E. W C.-E. Wulz ulz

Combination with displaced jet analysis in muon system

arXiV 1811.07370

Related analysis with CR jet and Z: arXiV 1811.02542

Φ/H Z Zd p p l+ l− q ¯ q

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Emer Emerging jets ging jets

CMS-EXO-18-001, arXiV: 1810.0169 Dark QCD model arXiV:1502.05409

Mediator XDK , dark fermions Qd
Hadronization of QDK to e.g. dark pions (πDK)
Displaced decays of πDK back to SM particles
Exponential decay of πDK

14

Emerging Jet

Background

data-driven estimate from 4-jet sample without

emergent jets

misidentification probability of regular jet as

emerging jet modelled, depending on parton flavour and jet multiplicity

Track multiplicity 10 20 30 40 Misidentification probability

5 −

10

4 −

10

3 −

10

2 −

10

1 −

10 1

EMJ-1 b jet Light-flavor jet (13 TeV)

1

16.1 fb

CMS

C.-E. Wulz

Trigger and signature

HT > 900 GeV
2 calorimeter jets with displaced tracks and many

different vertices within the jet cone

2 regular jets

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Emer Emerging jets ging jets

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[GeV]

DK

X

m

400 600 800 1000 1200 1400 1600 1800 2000

[mm]

DK

π

τ c

95% CL upper limit on cross section [fb]

1 10

2

10

3

10 1 10

2

10

3

10

Observed limit Expected limit σ 1 ± Expected limit

= 5 GeV

DK

π

m

CMS

(13 TeV)

1

16.1 fb

3D

α

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Fraction of Jets / 0.05

3 −

10

2 −

10

1 −

10 1 10

QCD light jets = 1 mm

DK

π

τ c = 5 mm

DK

π

τ c = 25 mm

DK

π

τ c = 60 mm

DK

π

τ c = 100 mm

DK

π

τ c = 300 mm

DK

π

τ c

(13 TeV)

CMS

Simulation

m(πD) = 5 GeV

Mediator masses excluded between 400 and 1250 GeV for decay lengths 5 to 225 mm

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Fraction of jet pT associated with prompt tracks

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400 − 300 − 200 − 100 − 100 200 300 400 [cm]

vtx

Signed r

1 −

10 1 10

2

10 Vertices / 10 cm ATLAS Simulation = 13 TeV s

1

32.9 fb

high

SR

= 1 m τ = 300 GeV, c

1

χ ∼

m = 1 m τ = 700 GeV, c

1

χ ∼

m = 1 m τ = 1000 GeV, c

1

χ ∼

m

400 − 300 − 200 − 100 − 100 200 300 400 [cm]

vtx

Signed r 1 10

2

10

3

10

4

10

5

10

6

10

7

10 Vertices / 10 cm ATLAS = 13 TeV s

1

32.9 fb

−

µ

+

µ

Drell-Yan t t Single top quark Data

Displaced Displaced dimuons imuons

arXiV: 1808.03057, PRD 99 (2019) 012001 Model assumptions and search strategy

Long-lived neutralinos in GMSB scenario
Long-lived dark photons ZD from Higgs decay
High-mass (Z → μ+μ-) and low-mass (ZD → μ+μ-)
m(χ1

0) = 300-1100 GeV, m(ZD) = 20-60 GeV

Signature and trigger

2 opposite-sign μ in muon system with vertex up to 4 m from interaction point
1μ trigger efficiency 70% at IP

, 10% at 4m → MET trigger compensates

C.-E. Wulz 16 ˜ g ˜ g ˜ χ0

1

Z ˜ χ0

1

Z p p q q ˜ G µ µ q q ˜ G f f H ZD p p ZD µ µ ⇣ ✏ Signal type Trigger Description Thresholds High mass Emiss

T

missing transverse momentum Emiss

T

> 110 GeV single muon single muon restricted to the barrel region muon |η| < 1.05 and pT > 60 GeV Low mass collimated dimuon two muons with small angular separation pT of muons > 15 and 20 GeV and ∆Rµµ < 0.5 trimuon three muons pT > 6 GeV for all three muons

~

Multijet bkg not included Signal (simulation)

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50 100 150 200 250 300 350 400 [GeV]

µ µ

m 1 2 3 4 5 6 7 Vertices / 5 GeV ATLAS

1

32.9 fb = 13 TeV s

low

data, SR

high

data, SR

300 − 200 − 100 − 100 200 300 [cm]

vtx

Signed r 1 2 3 4 5 6 7 8 Vertices / 10 cm ATLAS

1

32.9 fb = 13 TeV s

low

data, SR

high

data, SR

Displaced Displaced dimuons imuons

C.-E. Wulz 17

Z cosmic

1 −

10 1 10

2

10

3

10

4

10

5

10

6

10

7

10 [cm] τ c

4 −

10

3 −

10

2 −

10

1 −

10 1 10

2

10 [pb] B x σ 95% CL upper limit

(1100 GeV) = 0.163 pb

g ~

σ ) = 1 G ~ Z →

1

χ ∼ ( B = 1000 GeV

1

χ ∼

m Observed Expected σ 1 ± σ 2 ±

ATLAS = 13 TeV s

1

32.9 fb

1 −

10 1 10

2

10

3

10

4

10

5

10

6

10

7

10 [cm] τ c

3 −

10

2 −

10

1 −

10 1 10

2

10

3

10 [pb] B x σ 95% CL upper limit

) = 0.1

D

Z

D

Z → (H B ) = 0.01

D

Z

D

Z → (H B ) = 0.107 µ µ →

D

(Z B = 60 GeV

D

Z

m Observed Expected σ 1 ± σ 2 ±

ATLAS = 13 TeV s

1

32.9 fb

No significant excess in number of vertices above background -> lower and upper lifetime limits from 0.3 to 2400 cm, depending on model parameters

GMSB model Dark photon model

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ATLAS LLP sear TLAS LLP searches ches – 95% CL exclusion 95% CL exclusion

Model Signature

L dt [fb−1]

Lifetime limit Reference

SUSY Higgs BR = 10% Scalar Other

RPV χ0

1 → eeν/eµν/µµν

displaced lepton pair 20.3 1504.05162 7-740 mm χ0

1 lifetime

m(˜ g)= 1.3 TeV, m(χ0

1)= 1.0 TeV

GGM χ0

1 → Z ˜

G displaced vtx + jets 20.3 1504.05162 6-480 mm χ0

1 lifetime

m(˜ g)= 1.1 TeV, m(χ0

1)= 1.0 TeV

GGM χ0

1 → Z ˜

G displaced dimuon 32.9 1808.03057 0.029-18.0 m χ0

1 lifetime

m(˜ g)= 1.1 TeV, m(χ0

1)= 1.0 TeV

GMSB non-pointing or delayed γ 20.3 1409.5542 0.08-5.4 m χ0

1 lifetime SPS8 with Λ= 200 TeV

AMSB pp → χ±

1χ0 1, χ+ 1 χ− 1

disappearing track 20.3 1310.3675 0.22-3.0 m χ±

1 lifetime

m(χ±

1)= 450 GeV

AMSB pp → χ±

1χ0 1, χ+ 1 χ− 1

disappearing track 36.1 1712.02118 0.057-1.53 m χ±

1 lifetime

m(χ±

1)= 450 GeV

AMSB pp → χ±

1χ0 1, χ+ 1 χ− 1

large pixel dE/dx 18.4 1506.05332 1.31-9.0 m χ±

1 lifetime

m(χ±

1)= 450 GeV

Stealth SUSY 2 ID/MS vertices 19.5 1504.03634 0.12-90.6 m ˜ S lifetime m(˜ g)= 500 GeV Split SUSY large pixel dE/dx 36.1 1808.04095 > 0.9 m ˜ g lifetime m(˜ g)= 1.8 TeV, m(χ0

1)= 100 GeV

Split SUSY displaced vtx + E miss

T

32.8 1710.04901 0.03-13.2 m ˜ g lifetime m(˜ g)= 1.8 TeV, m(χ0

1)= 100 GeV

Split SUSY 0 ℓ, 2 − 6 jets +E miss

T

36.1 ATLAS-CONF-2018-003 0.0-2.1 m ˜ g lifetime m(˜ g)= 1.8 TeV, m(χ0

1)= 100 GeV

H → s s low-EMF trk-less jets, MS vtx 36.1 1902.03094 0.18-120.0 m s lifetime

m(s)= 25 GeV FRVZ H → 2γd + X 2 e−, µ−jets 20.3 1511.05542 0-3 mm

γd lifetime

m(γd)= 400 MeV FRVZ H → 2γd + X 2 e−, µ−, π−jets 3.4 ATLAS-CONF-2016-042 0.022-1.113 m

γd lifetime

m(γd)= 400 MeV FRVZ H → 4γd + X 2 e−, µ−, π−jets 3.4 ATLAS-CONF-2016-042 0.038-1.63 m

γd lifetime

m(γd)= 400 MeV

H → ZdZd displaced dimuon 32.9 1808.03057 0.009-24.0 m Zd lifetime

m(Zd)= 40 GeV

H → ZZd 2 e, µ + low-EMF trackless jet 36.1 1811.02542 0.22-5.3 m Zd lifetime

m(Zd)= 10 GeV

VH with H → ss → bbbb 1 − 2ℓ + multi-b-jets 36.1 1806.07355 0-3 mm s lifetime

B(H → ss)= 1, m(s)= 60 GeV

Φ(200 GeV) → s s low-EMF trk-less jets, MS vtx 36.1 1902.03094 0.41-51.5 m s lifetime

σ × B= 1 pb, m(s)= 50 GeV

Φ(600 GeV) → s s low-EMF trk-less jets, MS vtx 36.1 1902.03094 0.04-21.5 m s lifetime

σ × B= 1 pb, m(s)= 50 GeV

Φ(1 TeV) → s s low-EMF trk-less jets, MS vtx 36.1 1902.03094 0.06-52.4 m s lifetime

σ × B= 1 pb, m(s)= 150 GeV HV Z ′(1 TeV) → qvqv 2 ID/MS vertices 20.3 1504.03634 0.1-4.9 m

s lifetime

σ × B= 1 pb, m(s)= 50 GeV HV Z ′(2 TeV) → qvqv 2 ID/MS vertices 20.3 1504.03634 0.1-10.1 m

s lifetime

σ × B= 1 pb, m(s)= 50 GeV

cτ [m] τ [ns]

0.01 0.01 0.1 0.1 1 1 10 10 100 100

√s = 8 TeV √s = 13 TeV

ATLAS Long-lived Particle Searches* - 95% CL Exclusion

Status: March 2019

ATLAS Preliminary

L dt = (3.4 – 36.1) fb−1 √s = 8, 13 TeV

*Only a selection of the available lifetime limits is shown.

March 2019

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Bibl Bibliography iography

ATLAS

ht https:// tps://twiki.cer twiki.cern.ch n.ch/twiki twiki/bin/view/ /bin/view/At AtlasPubl lasPublic ic/Exot ExoticsPubl icsPublicResul icResults ts

Displaced hadronic jets in calorimeter: arXiv 1902.03094, EXOT-2017-025
Displaced hadronic jets in muon spectrometer: arXiv 1811.07370, hepdata 1704138,

EXOT-2017-025

LLP decaying in calorimeter in association with Z boson: arXiv 1811.02542, hepdata

1702261, EXOT-2017-024

Displaced dimuon vertices: PRD 99 (2019) 012001, arXiv 1808.03057, EXOT-2017-024

ht https:// tps://twiki.cer twiki.cern.ch n.ch/twiki twiki/bin/view/ /bin/view/At AtlasPubl lasPublic ic/SupersymmetryPubl SupersymmetryPublicResul icResults ts

Displaced vertices plus MET: PRD 97 (2018) 052012, arXiv 1710.04901, hepdata 78697,

SUS-2016-08

Variable RPV coupling strength and LL R-hadrons: ATLAS-CONF-2018-003

CMS

ht https:// tps://cms-r cms-resul esults.web.cer ts.web.cern.ch n.ch/cms cms-r

resul

esults/publ ts/public-r ic-resul esults/publ ts/publicat ications ions

Delayed jets: EXO-19-001
Displaced vertices in multijet events: PRD 98 (2018) 092011, arXiV 1808.03078, hepdata

1685992, EXO-17-018

Emerging jets: JHEP 02 (2019) 179, arXiV 1810.10069, hepdata 1700173, EXO-18-001
Displaced jets: PRD 99 (2019) 032011, arXiV 1811.07991, EXO-18-007

C.-E. Wulz 19

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Conclusions Conclusions

C.-E. Wulz 20

Searches for long-lived particles are underway
Full Run 2 analyses will be published soon
Non-standard trigger, data acquisition and analysis

strategies and techniques are being further developed

Detector hardware and trigger upgrades will come to

play in the HL-LHC phase I always believed in leaving no stone unturned Arnold Schwarzenegger

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BACKUP BACKUP

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[m] τ c

4

10

2

10 1

2

10

4

10

6

10

8

10

12

10

) = 200 GeV

1 ±

χ ∼ > 0, m( µ ) = 5, β , tan(

1 ±

χ ∼ AMSB (tracker + TOF)

1

8 TeV, 18.8 fb ) = 800 GeV

1 ±

χ ∼ > 0, m( µ ) = 5, β , tan(

1 ±

χ ∼ AMSB (tracker + TOF)

1

8 TeV, 18.8 fb ) = 1000 GeV g ~ cloud model R-hadron, m( (stopped particle)

1

8 TeV, 18.6 fb ) = 200 GeV

1 ±

χ ∼ , m(

±

π +

1

χ ∼ →

1 ±

χ ∼ ,

1 ±

χ ∼ AMSB (disappearing tracks)

1

8 TeV, 19.5 fb ) = 500 GeV

1

χ ∼ ) = 1000 GeV, m( q ~ RPV SUSY, m( (displaced dijets)

1

8 TeV, 18.5 fb ) = 150 GeV

1

χ ∼ ) = 1000 GeV, m( q ~ RPV SUSY, m( (displaced dijets)

1

8 TeV, 18.5 fb ) = 250 GeV

1

χ ∼ , m( γ G ~ →

1

χ ∼ GMSB SPS8, (disp. photon timing)

1

8 TeV, 19.1 fb ) = 250 GeV

1

χ ∼ , m( γ G ~ →

1

χ ∼ GMSB SPS8, (disp. photon conv.)

1

8 TeV, 19.7 fb , m(H) = 125 GeV, m(X) = 20 GeV µ µ → XX (10%), X → H (displaced leptons)

1

8 TeV, 20.5 fb ee, m(H) = 125 GeV, m(X) = 20 GeV → XX (10%), X → H (displaced leptons)

1

8 TeV, 19.6 fb ) = 420 GeV t ~ bl, m( → t ~ RPV SUSY, (displaced leptons)

1

8 TeV, 19.7 fb

CMS long-lived particle searches, lifetime exclusions at 95% CL

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CMS LLP sear CMS LLP searches ches – 95% CL exclusion 95% CL exclusion

August 2016

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Emer Emerging jet event in CMS ging jet event in CMS

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Emer Emerging jet event in CMS ging jet event in CMS

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Emer Emerging jet event in CMS ging jet event in CMS

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Search for LLP with displaced vertices in multijet events

˜ χ0, ˜ g ˜ χ0, ˜ g ˜ t ˜ t p p ¯ t ¯ b ¯ s ¯ s ¯ b ¯ t ˜ t∗ ˜ t p p d d ¯ d ¯ d

(GeV)

g ~ / χ ∼

m

500 1000 1500 2000 2500

(mm) τ c

10 20 30 40 50 60 70 80 90 100

(fb)

2

Β σ 95% CL upper limit on

1 10 1

tbs → g ~ Observed Expected

CMS (13 TeV)

1

38.5 fb (GeV)

t ~

m

500 1000 1500 2000 2500

(mm) τ c

10 20 30 40 50 60 70 80 90 100

(fb)

2

Β σ 95% CL upper limit on

1 10 1

d d → t ~ Observed Expected

CMS (13 TeV)

1

38.5 fb (GeV)

g ~ / χ ∼

m

500 1000 1500 2000 2500

(mm) τ c

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

(fb)

2

Β σ 95% CL upper limit on

1 10

2

10

tbs → g ~ Observed Expected

CMS (13 TeV)

1

38.5 fb (GeV)

t ~

m

500 1000 1500 2000 2500

(mm) τ c

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

(fb)

2

Β σ 95% CL upper limit on

1 10

2

10

d d → t ~ Observed Expected

CMS (13 TeV)

1

38.5 fb

(mm)

VV

d

0.5 1 1.5 2 2.5 3 3.5 4

Events/0.1 mm

0.2 0.4 0.6 0.8 1

Background template = 1 fb: σ m = 800 GeV, Multijet signals, = 0.3 mm τ c = 1.0 mm τ c = 10 mm τ c

CMS (13 TeV)

1

38.5 fb

18.2

Background estimation:

Construct shape of background dVV distribution

from ≥5-track one-vertex events in data.

Validate construction method using events with

3-track and 4-track vertices.

CMS-EXO-17-018, arXiv:1808.03078, PRD 98, 092011 (2018) Signal model:

Pair production of LLP decaying to multiple jets.
Focus on intermediate signal lifetimes

(0.1 ≤ cτ ≤ 100 mm).

Search strategy:

Custom vertex reconstruction algorithm

identifies displaced vertices from tracks.

Signal region: ≥5-track two-vertex events.
Search variable: distance between vertices dVV.