Tagging strange jets & constraining h s s Matthias Schlaffer - - PowerPoint PPT Presentation

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Tagging strange jets & constraining h s s Matthias Schlaffer - - PowerPoint PPT Presentation

Sep 23, 2022 127 likes •593 views

Tagging strange jets & constraining h s s Matthias Schlaffer Weizmann Institute of Science based on: 1811.09636 (J. Duarte-Campderros, G. Perez, MS, A. Soffer) work in progress 4th NPKI workshop, Seoul May 2019 Gauge boson masses

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SLIDE 1

Tagging strange jets & constraining h → s¯ s

Matthias Schlaffer

Weizmann Institute of Science based on: 1811.09636 (J. Duarte-Campderros, G. Perez, MS, A. Soffer) work in progress 4th NPKI workshop, Seoul May 2019

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SLIDE 2

Gauge boson masses

Higgs is main source of electroweak symmetry breaking!

Parameter value 2 − 1 − 1 2 3 µ µ

µ

bb

µ

τ τ

µ

WW

µ

ZZ

µ

γ γ

µ

CMS

(13 TeV)

  • 1

35.9 fb Observed syst) ⊕ (stat σ 1 ± syst) ⊕ (stat σ 2 ± (syst) σ 1 ±

µX = BRX|meas.

BRX|SM

[CMS: 1809.10733]

Higgs couples to gauge bosons as expected

Matthias Schlaffer 1

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SLIDE 3

What about fermion masses and the flavor structure?

SM: economic solution, Higgs does it! ψ ψ h ⇒ v ψ ψ ⇒ mψ ∝ y Does it? ✸ tth, h → ττ, h → bb > 5σ ( ) ✸ h → µµ: µµµ < 2.8 at 95 % CL

[ATLAS: 1705.04582]

Other fermions, especially quarks, much less constrained ⇒ flavor puzzle unsolved E.g. Yukawa modifications

v

V

m

V

κ

  • r

v

F

m

F

κ

4 −

10

3 −

10

2 −

10

1 −

10 1

W t Z b µ τ

SM Higgs boson ) fit ε (M, σ 1 ± σ 2 ±

(13 TeV)

  • 1

35.9 fb

CMS

Particle mass [GeV]

1 −

10 1 10

2

10

Ratio to SM

0.5 1 1.5

[CMS: 1809.10733]

Matthias Schlaffer 2

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SLIDE 4

Difficulties

i) small branching ratio

[GeV]

H

M

120 121 122 123 124 125 126 127 128 129 130

Branching Ratio

  • 4

10

  • 3

10

  • 2

10

  • 1

10 1

LHC HIGGS XS WG 2016

b b τ τ µ µ c c gg γ γ ZZ WW γ Z

[LHCHXSWG]

| | | | | | | | | | u p d

  • w

n c h a r m s t r a n g e t

  • p

b

  • t

t

  • m

e l e c t r

  • n

m u

  • n

t a u H i g g s 106 107 108 109 1010 1011 1012 Mass [eV] Matthias Schlaffer 3

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SLIDE 5

Difficulties

i) small branching ratio

[GeV]

H

M

120 121 122 123 124 125 126 127 128 129 130

Branching Ratio

  • 4

10

  • 3

10

  • 2

10

  • 1

10 1

LHC HIGGS XS WG 2016

b b τ τ µ µ c c gg γ γ ZZ WW γ Z

[LHCHXSWG]

| | | | | | | | | | u p d

  • w

n c h a r m s t r a n g e t

  • p

b

  • t

t

  • m

e l e c t r

  • n

m u

  • n

t a u H i g g s 106 107 108 109 1010 1011 1012 Mass [eV]

ii) difficult final state for quarks > quarks appear as jets > large background > hard to distinguish Nevertheless: h → cc will be measured at % level at FCC-ee

[Dawson et.al ’13]

What about strange?

Matthias Schlaffer 3

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SLIDE 6

Exclusive decay h → φγ [Bodwin et.al ’13, Kagan et.al ’14]

  • φ

h γ ¯ s s +

  • φ

h γ ¯ s s > Clean decay: BR(φ(s¯ s) → K+(u¯ s) + K−(¯ us)) ≈ 50% > BUT: BR(h → φγ) ≈ 2 × 10−6 [König et.al ’15] > compare BR(h → s¯ s) ≈ 2 × 10−4 > only weak limit at future (hadron) colliders [Kagan et.al ’14] estimate: µss O(107) @HL-LHC > current limit: BR(h → φγ) < 4.8 × 10−4 [ATLAS ’17] Ideas to use differential distributions [see e.g. Bishara et.al ’16, Soreq

et.al ’16, Yu ’16, Carpenter et.al ’16]

Matthias Schlaffer 4

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SLIDE 7

Brute force method

Alternative ansatz: > FCC-ee will produce 106 Higgses via e− e+ Z∗ Z h > O(200) of which decay into strange quarks > tag strange jets > Done before in Z → s¯ s

– Measurement of the strange quark forward backward asymmetry around the Z0 peak [DELPHI Collaboration, Eur.Phys.J. C14 (2000)] – Light quark fragmentation in polarized Z0 decays [SLD Collaboration, Nucl.Phys.Proc.Suppl. 96 (2001)]

Matthias Schlaffer 5

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SLIDE 8

Jet-Flavor

> define flavor of jet for light quarks and gluon > strange quarks fragment more likely into hard kaons

1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 z 10

3

10

2

10

1

100 Fs +(z) Q2 = m2

h

+

K + JAM17 Pythia 8 Herwig MG5aMC@NLO + Pythia 8

Matthias Schlaffer 6

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SLIDE 9

Jet-Flavor

> define flavor of jet for light quarks and gluon > strange quarks fragment more likely into hard kaons

1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 z 10

3

10

2

10

1

100 Fg(z) Q2 = m2

h

+

K + Pythia 8 Herwig

Matthias Schlaffer 7

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SLIDE 10

Jet-Flavor

> define flavor of jet for light quarks and gluon > strange quarks fragment more likely into hard kaons π+ π− K+ JF =

  • H∈j

pH · ˆ sRH

  • H∈j

pH · ˆ s

Matthias Schlaffer 8

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SLIDE 11

Jet-Flavor

> define flavor of jet for light quarks and gluon > strange quarks fragment more likely into hard kaons K+ K− K+ JF =

  • H∈j

pH · ˆ sRH

  • H∈j

pH · ˆ s

Matthias Schlaffer 8

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SLIDE 12

Jet-Flavor

> define flavor of jet for light quarks and gluon > strange quarks fragment more likely into hard kaons > Js: RK± = ∓1, RKs = ±1 minimizing Js, else 0 > counts collinear hard strange content > not safe against collinear emission

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 Js 10−1 100 101 fraction of events / 0.02

h → u¯ u h → d ¯ d h → s¯ s h → gg Herwig Pythia 8

Matthias Schlaffer 9

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SLIDE 13

Reject heavy flavor

> Minimalistic approach: Just cut on largest impact parameter > Require plab > 5 GeV ⇒ ∆d0 10 µm > Smear truth values > Include 5 µm uncertainty on IP

0.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 d0 [µm] 0.00 0.02 0.04 0.06 0.08 fraction of events / 0.5 µm

h → u¯ u h → d ¯ d h → c¯ c h → s¯ s h → b¯ b h → gg W →had. Herwig Pythia 8

Matthias Schlaffer 10

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SLIDE 14

Setup and assumptions

data ⇒ kinematic separation cut&count, BDT,...

h → jj

  • ther bkg

s-tagger ⇒ limit

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SLIDE 15

Setup and assumptions

data ⇒ kinematic separation cut&count, BDT,...

h → jj

  • ther bkg

s-tagger ⇒ limit Part I: > Clean sample with hadronic Higgses > Only background other Higgs decays (h → gg, bb, cc) > We know which jets originate from the Higgs decay > Generate and shower with PYTHIA and Herwig > No detector simulation

Matthias Schlaffer 11

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SLIDE 16

Kaon reconstruction

Charged kaons: > stable on detector scales > tracking efficiency 95% > Particle ID π± K±

some observable 2 σ bench marks e.g.: > no ID > ǫK = 95% ǫπ = 12%

σ

Matthias Schlaffer 12

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SLIDE 17

Kaon reconstruction

Charged kaons: > stable on detector scales > tracking efficiency 95% > Particle ID π± K±

some observable 2 σ bench marks e.g.: > no ID > ǫK = 95% ǫπ = 12%

0.1 0.5 1 5 10 50 100 0.0 0.5 1.0 1.5 2.0 2.5 3.0 p [GeV]

σ

dE/dx resolution 10% 7% 6% 5% 4%

Matthias Schlaffer 12

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SLIDE 18

Kaon reconstruction

Charged kaons: > stable on detector scales > tracking efficiency 95% > Particle ID π± K±

some observable 2 σ bench marks e.g.: > no ID > ǫK = 95% ǫπ = 12%

0.1 0.5 1 5 10 50 100 0.0 0.5 1.0 1.5 2.0 2.5 3.0 p [GeV]

σ

dE/dx resolution 10% 7% 6% 5% 4%

[1811.10545]

Matthias Schlaffer 12

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SLIDE 19

Kaon reconstruction

Charged kaons: > stable on detector scales > tracking efficiency 95% > Particle ID π± K±

some observable 2 σ bench marks e.g.: > no ID > ǫK = 95% ǫπ = 12%

0.1 0.5 1 5 10 50 100 0.0 0.5 1.0 1.5 2.0 2.5 3.0 p [GeV]

σ

dE/dx resolution 10% 7% 6% 5% 4%

[1811.10545]

IDEA Drift chamber

0" 1" 2" 3" 4" 5" 6" 7" 8" 9" 10" 0.1" 1" 10" 100"

#"of"sigma" Momentum"[GeV/c]"

Par7cle"Separa7on"(dE/dx"vs"dN/dx)"

µ-π π-Κ Κ-p

[FCC-ee CDR]

Matthias Schlaffer 12

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SLIDE 20

Kaon reconstruction

Neutral kaons: > Decay length ∼ 80 cm > Needs to decay to π± within 5 mm < R < 1 m > reco efficiency 80%

Matthias Schlaffer 13

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SLIDE 21

Efficiencies

> impact parameter d0 < 15µm

0.05 0.10 0.15 0.20 0.25 Js 10−4 10−3 10−2 10−1 ǫ

h → u¯ u h → d ¯ d h → c¯ c h → s¯ s h → b¯ b h → gg W →had. Herwig Pythia 8

no particle ID

Matthias Schlaffer 14

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SLIDE 22

Efficiencies

> impact parameter d0 < 15µm

0.05 0.10 0.15 0.20 0.25 Js 10−4 10−3 10−2 10−1 ǫ

h → u¯ u h → d ¯ d h → c¯ c h → s¯ s h → b¯ b h → gg W →had. Herwig Pythia 8

with particle ID: ǫK = 95%, ǫπ = 12%

Matthias Schlaffer 14

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SLIDE 23

Number of events

> impact parameter d0 < 15µm

0.05 0.10 0.15 0.20 0.25 Js 10−9 10−8 10−7 10−6 10−5 10−4 10−3 10−2 BR · ǫ

h → u¯ u h → d ¯ d h → c¯ c h → s¯ s h → b¯ b h → gg Herwig Pythia 8

no particle ID

Matthias Schlaffer 15

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SLIDE 24

Number of events

> impact parameter d0 < 15µm

0.05 0.10 0.15 0.20 0.25 Js 10−10 10−9 10−8 10−7 10−6 10−5 10−4 10−3 10−2 BR · ǫ

h → u¯ u h → d ¯ d h → c¯ c h → s¯ s h → b¯ b h → gg Herwig Pythia 8

with particle ID: ǫK = 95%, ǫπ = 12%

Matthias Schlaffer 15

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SLIDE 25

Results part I

0.05 0.10 0.15 0.20 0.25 Js 0.6 0.8 1.0 1.2 1.4 1.6 1.8 S/ √ B

d0 = 0.015 mm, ǫK± = 0.88 d0 = 0.013 mm, ǫK± = 0.92 Herwig Pythia 8

NHiggs = 107 > strange Yukawa within reach of FCC-ee! > Improvements possible

Matthias Schlaffer 16

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SLIDE 26

Realistic Collider

Existing studies for h → bb, cc, gg: > Cut&Count: mh = 120 GeV [Ono et.al ’12] > BDT [Talk by Yu Bai @ CEPC meeting] Assumptions: > hνν final state (don’t consider hℓℓ or hqq) > Non-h → jj flavor composition as in BDT study

e+e− → WW Z(Z + γ∗) Zh + ννh Z(Z + γ∗) Final state (τν)(qq′) (νν)(dd, ss, bb) (νν)(non-jj) (νν)(uu, cc) Fraction [%] 47.1 18.0 13.7 12.2 ⇒ flavor W bb uu dd cc ss gg relative abundance 65.3 9.8 6.1 6.0 6.4 6.0 0.2

> ǫW from ee → WW

Matthias Schlaffer 17

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SLIDE 27

Results part II

data ⇒ kinematic separation cut&count, BDT,...

h → jj

x

  • ther bkg

y s-tagger ⇒ limit x-Axis: Njj = LσhBRjjǫjj y-Axis: Nnon-jj = L

i∈non-jj ǫi

For each point (x,y) find best cut values to minimize upper limit

Matthias Schlaffer 18

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SLIDE 28

Results part II

102 103 104 105 106 107 Njj 102 103 104 105 106 107 Nnon−jj

Cut & Count BDT L = 250 fb−1 L = 5 ab−1 L = 20 ab−1

0.92 0.93 0.94 0.95 0.96 0.97 0.98 0.99 1.0 ǫK±

Best choice of PID PYTHIA

Matthias Schlaffer 19

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SLIDE 29

Results part II

102 103 104 105 106 107 Njj 102 103 104 105 106 107 Nnon−jj

Cut & Count BDT L = 250 fb−1 L = 5 ab−1 L = 20 ab−1

0.013 0.014 0.015 0.016 0.017 0.018 0.019 0.02 0.021 0.022 0.023 0.024 d0 [mm]

Best choice of d0 cut PYTHIA

Matthias Schlaffer 19

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SLIDE 30

Results part II

102 103 104 105 106 107 Njj 102 103 104 105 106 107 Nnon−jj

Cut & Count BDT L = 250 fb−1 L = 5 ab−1 L = 20 ab−1

0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 0.06 0.065 0.07 0.075 0.08 0.085 0.09 0.095 0.1 0.105 0.11 0.115 0.12 0.125 0.13 0.135 0.14 0.145 0.15 0.155 0.16 0.165 0.17 0.175 0.18 0.185 0.19 0.195 0.2 0.205 0.21 0.215 0.22 Js

Best choice of Js cut PYTHIA

0.20 0.15 0.10 0.05 Matthias Schlaffer 19

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SLIDE 31

Results part II

102 103 104 105 106 107 Njj 102 103 104 105 106 107 Nnon−jj

Cut & Count BDT L = 250 fb−1 L = 5 ab−1 L = 20 ab−1

1 2 5 10 20 50 100 200 95% CL on µ

Upper limit on µ PYTHIA

Matthias Schlaffer 19

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SLIDE 32

Results part II

102 103 104 105 106 107 Njj 102 103 104 105 106 107 Nnon−jj

Cut & Count BDT L = 250 fb−1 L = 5 ab−1 L = 20 ab−1

1 2 5 10 20 50 100 200 95% CL on µ

Upper limit on µ Herwig

Matthias Schlaffer 19

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SLIDE 33

Conclusion

> s-tagger in the context of h → s¯ s > proof-of-concept, can be improved > validation possible with large data sets of WW and Z > with 10 ab−1 (FCC-ee): µs 20 > compare with HL-LHC: µs 107 > applicable to other searches with s-jets (up to some modifications)

Thank You

Matthias Schlaffer 20

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SLIDE 34

BACKUP

Matthias Schlaffer 21

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SLIDE 35

Strange hadronization

In which kaons can a s quark hadronize? K± K0

S

K0

L

Matthias Schlaffer 22

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SLIDE 36

Strange hadronization

In which kaons can a s quark hadronize? K± vis. 1/6 inv.1/3

Matthias Schlaffer 22

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SLIDE 37

Results (extended version)

102 103 104 105 106 107 Njj 102 103 104 105 106 107 Nnon−jj

Cut & Count BDT L = 250 fb−1 L = 5 ab−1 L = 20 ab−1

0.92 0.93 0.94 0.95 0.96 0.97 0.98 0.99 1.0 ǫK±

Best choice of PID PYTHIA

Matthias Schlaffer 23

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SLIDE 38

Results (extended version)

102 103 104 105 106 107 Njj 102 103 104 105 106 107 Nnon−jj

Cut & Count BDT L = 250 fb−1 L = 5 ab−1 L = 20 ab−1

0.88 0.9 0.92 0.94 0.96 0.98 1.0 ǫK±

Best choice of PID Herwig

Matthias Schlaffer 23

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SLIDE 39

Results (extended version)

102 103 104 105 106 107 Njj 102 103 104 105 106 107 Nnon−jj

Cut & Count BDT L = 250 fb−1 L = 5 ab−1 L = 20 ab−1

0.013 0.014 0.015 0.016 0.017 0.018 0.019 0.02 0.021 0.022 0.023 0.024 d0 [mm]

Best choice of d0 cut PYTHIA

Matthias Schlaffer 23

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SLIDE 40

Results (extended version)

102 103 104 105 106 107 Njj 102 103 104 105 106 107 Nnon−jj

Cut & Count BDT L = 250 fb−1 L = 5 ab−1 L = 20 ab−1

0.015 0.016 0.017 0.018 0.019 0.02 0.021 0.022 0.023 0.024 0.025 d0 [mm]

Best choice of d0 cut Herwig

Matthias Schlaffer 23

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SLIDE 41

Results (extended version)

102 103 104 105 106 107 Njj 102 103 104 105 106 107 Nnon−jj

Cut & Count BDT L = 250 fb−1 L = 5 ab−1 L = 20 ab−1

0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 0.06 0.065 0.07 0.075 0.08 0.085 0.09 0.095 0.1 0.105 0.11 0.115 0.12 0.125 0.13 0.135 0.14 0.145 0.15 0.155 0.16 0.165 0.17 0.175 0.18 0.185 0.19 0.195 0.2 0.205 0.21 0.215 0.22 Js

Best choice of Js cut PYTHIA

0.20 0.15 0.10 0.05 Matthias Schlaffer 23

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SLIDE 42

Results (extended version)

102 103 104 105 106 107 Njj 102 103 104 105 106 107 Nnon−jj

Cut & Count BDT L = 250 fb−1 L = 5 ab−1 L = 20 ab−1

0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 0.06 0.065 0.07 0.075 0.08 0.085 0.09 0.095 0.1 0.105 0.11 0.115 0.12 0.125 0.13 0.135 0.14 0.145 0.15 0.155 0.16 0.165 0.17 0.175 0.18 0.185 0.19 0.195 Js

Best choice of Js cut Herwig

0.15 0.10 0.05 Matthias Schlaffer 23

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SLIDE 43

Results (extended version)

102 103 104 105 106 107 Njj 102 103 104 105 106 107 Nnon−jj

Cut & Count BDT L = 250 fb−1 L = 5 ab−1 L = 20 ab−1

1 2 5 10 20 50 100 200 95% CL on µ

Upper limit on µ PYTHIA

Matthias Schlaffer 23

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SLIDE 44

Results (extended version)

102 103 104 105 106 107 Njj 102 103 104 105 106 107 Nnon−jj

Cut & Count BDT L = 250 fb−1 L = 5 ab−1 L = 20 ab−1

1 2 5 10 20 50 100 200 95% CL on µ

Upper limit on µ Herwig

Matthias Schlaffer 23

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SLIDE 45

Impact parameter resolution

∆d0 =

  • ∆2

IP + (5 µm)2 +

  • 10

p sin3/2 θ

2

0.0 0.5 1.0 1.5 5 10 15 20

θ Δd0 [μm]

p=2GeV p=5GeV p=10GeV p=20GeV

Matthias Schlaffer 24